diff --git a/.eslintrc.yml b/.eslintrc.yml
index 34000ab..2ebe71d 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -1,8 +1,9 @@
 # https://eslint.org/docs/rules/
 
 root: true
+parser: '@typescript-eslint/parser'
 parserOptions:
-  sourceType: script
+  sourceType: module
   ecmaVersion: 2018
 env:
   es6: true
@@ -10,10 +11,14 @@ env:
 plugins:
   - prettier
   - import
+  - '@typescript-eslint'
+ignorePatterns:
+  - lib
+
 extends:
-  - eslint:recommended
-  - plugin:import/recommended
   - plugin:prettier/recommended
+  - plugin:@typescript-eslint/eslint-recommended
+
 rules:
   # Prettier
   prettier/prettier:
@@ -118,7 +123,7 @@ rules:
   func-names:
     - 2
     - as-needed
-  func-style: 2
+  func-style: 0
   linebreak-style: 2
   lines-between-class-members: 2
   max-len:
diff --git a/.gitignore b/.gitignore
index 519a35e..7308a23 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@ node_modules/
 pkg/*
 test/.sass-cache/
 true-*.gem
+.idea
diff --git a/lib/constants.d.ts b/lib/constants.d.ts
new file mode 100644
index 0000000..0cb5e70
--- /dev/null
+++ b/lib/constants.d.ts
@@ -0,0 +1,22 @@
+export declare const MODULE_TOKEN = "# Module: ";
+export declare const MODULE_NESTING_TOKEN = " :: ";
+export declare const SUMMARY_TOKEN = "# SUMMARY ";
+export declare const END_SUMMARY_TOKEN = "----------";
+export declare const TEST_TOKEN = "Test: ";
+export declare const PASS_TOKEN = "\u2714 ";
+export declare const FAIL_TOKEN = "\u2716 FAILED: [";
+export declare const END_FAIL_TOKEN = "]";
+export declare const ASSERT_TOKEN = "ASSERT: ";
+export declare const FAILURE_DETAIL_TOKEN = "- ";
+export declare const FAILURE_TYPE_START_TOKEN = "[";
+export declare const FAILURE_TYPE_END_TOKEN = "]";
+export declare const OUTPUT_TOKEN = "Output: ";
+export declare const EXPECTED_TOKEN = "Expected: ";
+export declare const DETAILS_SEPARATOR_TOKEN = ": ";
+export declare const OUTPUT_START_TOKEN = "OUTPUT";
+export declare const OUTPUT_END_TOKEN = "END_OUTPUT";
+export declare const EXPECTED_START_TOKEN = "EXPECTED";
+export declare const EXPECTED_END_TOKEN = "END_EXPECTED";
+export declare const CONTAINED_START_TOKEN = "CONTAINED";
+export declare const CONTAINED_END_TOKEN = "END_CONTAINED";
+export declare const ASSERT_END_TOKEN = "END_ASSERT";
diff --git a/lib/constants.js b/lib/constants.js
new file mode 100644
index 0000000..a4093e8
--- /dev/null
+++ b/lib/constants.js
@@ -0,0 +1,27 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.ASSERT_END_TOKEN = exports.CONTAINED_END_TOKEN = exports.CONTAINED_START_TOKEN = exports.EXPECTED_END_TOKEN = exports.EXPECTED_START_TOKEN = exports.OUTPUT_END_TOKEN = exports.OUTPUT_START_TOKEN = exports.DETAILS_SEPARATOR_TOKEN = exports.EXPECTED_TOKEN = exports.OUTPUT_TOKEN = exports.FAILURE_TYPE_END_TOKEN = exports.FAILURE_TYPE_START_TOKEN = exports.FAILURE_DETAIL_TOKEN = exports.ASSERT_TOKEN = exports.END_FAIL_TOKEN = exports.FAIL_TOKEN = exports.PASS_TOKEN = exports.TEST_TOKEN = exports.END_SUMMARY_TOKEN = exports.SUMMARY_TOKEN = exports.MODULE_NESTING_TOKEN = exports.MODULE_TOKEN = void 0;
+// Tokens defining the True CSS output language.
+exports.MODULE_TOKEN = '# Module: ';
+exports.MODULE_NESTING_TOKEN = ' :: ';
+exports.SUMMARY_TOKEN = '# SUMMARY ';
+exports.END_SUMMARY_TOKEN = '----------';
+exports.TEST_TOKEN = 'Test: ';
+exports.PASS_TOKEN = '✔ ';
+exports.FAIL_TOKEN = '✖ FAILED: [';
+exports.END_FAIL_TOKEN = ']';
+exports.ASSERT_TOKEN = 'ASSERT: ';
+exports.FAILURE_DETAIL_TOKEN = '- ';
+exports.FAILURE_TYPE_START_TOKEN = '[';
+exports.FAILURE_TYPE_END_TOKEN = ']';
+exports.OUTPUT_TOKEN = 'Output: ';
+exports.EXPECTED_TOKEN = 'Expected: ';
+exports.DETAILS_SEPARATOR_TOKEN = ': ';
+exports.OUTPUT_START_TOKEN = 'OUTPUT';
+exports.OUTPUT_END_TOKEN = 'END_OUTPUT';
+exports.EXPECTED_START_TOKEN = 'EXPECTED';
+exports.EXPECTED_END_TOKEN = 'END_EXPECTED';
+exports.CONTAINED_START_TOKEN = 'CONTAINED';
+exports.CONTAINED_END_TOKEN = 'END_CONTAINED';
+exports.ASSERT_END_TOKEN = 'END_ASSERT';
+//# sourceMappingURL=constants.js.map
\ No newline at end of file
diff --git a/lib/constants.js.map b/lib/constants.js.map
new file mode 100644
index 0000000..224c488
--- /dev/null
+++ b/lib/constants.js.map
@@ -0,0 +1 @@
+{"version":3,"file":"constants.js","sourceRoot":"","sources":["../src/constants.ts"],"names":[],"mappings":";;;AAAA,gDAAgD;AACnC,QAAA,YAAY,GAAG,YAAY,CAAC;AAC5B,QAAA,oBAAoB,GAAG,MAAM,CAAC;AAC9B,QAAA,aAAa,GAAG,YAAY,CAAC;AAC7B,QAAA,iBAAiB,GAAG,YAAY,CAAC;AACjC,QAAA,UAAU,GAAG,QAAQ,CAAC;AACtB,QAAA,UAAU,GAAG,IAAI,CAAC;AAClB,QAAA,UAAU,GAAG,aAAa,CAAC;AAC3B,QAAA,cAAc,GAAG,GAAG,CAAC;AACrB,QAAA,YAAY,GAAG,UAAU,CAAC;AAC1B,QAAA,oBAAoB,GAAG,IAAI,CAAC;AAC5B,QAAA,wBAAwB,GAAG,GAAG,CAAC;AAC/B,QAAA,sBAAsB,GAAG,GAAG,CAAC;AAC7B,QAAA,YAAY,GAAG,UAAU,CAAC;AAC1B,QAAA,cAAc,GAAG,YAAY,CAAC;AAC9B,QAAA,uBAAuB,GAAG,IAAI,CAAC;AAC/B,QAAA,kBAAkB,GAAG,QAAQ,CAAC;AAC9B,QAAA,gBAAgB,GAAG,YAAY,CAAC;AAChC,QAAA,oBAAoB,GAAG,UAAU,CAAC;AAClC,QAAA,kBAAkB,GAAG,cAAc,CAAC;AACpC,QAAA,qBAAqB,GAAG,WAAW,CAAC;AACpC,QAAA,mBAAmB,GAAG,eAAe,CAAC;AACtC,QAAA,gBAAgB,GAAG,YAAY,CAAC"}
\ No newline at end of file
diff --git a/lib/index.d.ts b/lib/index.d.ts
new file mode 100644
index 0000000..6446514
--- /dev/null
+++ b/lib/index.d.ts
@@ -0,0 +1,36 @@
+import type { Options } from 'sass';
+import { Node } from 'css';
+export interface TrueOptions {
+    sass?: typeof import('sass');
+    describe: (description: string, fn: () => void) => void;
+    it: (description: string, fn: () => void) => void;
+    contextLines?: number;
+}
+export interface Assertion {
+    description: string;
+    output?: string;
+    assertionType?: string;
+    expected?: string;
+    details?: string;
+    passed?: boolean;
+}
+export interface Test {
+    test: string;
+    assertions: Assertion[];
+}
+export interface Module {
+    module: string;
+    tests: Test[];
+    modules?: Module[];
+}
+export declare type Context = {
+    modules: Module[];
+    currentModule?: Module;
+    currentTest?: Test;
+    currentAssertion?: Assertion;
+    currentOutputRules?: Node[];
+    currentExpectedRules?: Node[];
+};
+export declare function formatFailureMessage(assertion: Assertion): string;
+export declare function runSass(sassOptions: Options, trueOptions: TrueOptions): void;
+export declare function parse(rawCss: Readonly<string>, ctxLines?: Readonly<number>): Module[];
diff --git a/lib/index.js b/lib/index.js
new file mode 100644
index 0000000..9f71310
--- /dev/null
+++ b/lib/index.js
@@ -0,0 +1,405 @@
+"use strict";
+/* eslint-disable no-plusplus, no-unused-vars, no-var, no-use-before-define */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.parse = exports.runSass = exports.formatFailureMessage = void 0;
+var path = require("path");
+var assert = require("assert");
+var css = require("css");
+var lodash_1 = require("lodash");
+var chalk = require("chalk");
+var constants_1 = require("./constants");
+var utils_1 = require("./utils");
+function formatFailureMessage(assertion) {
+    var msg = assertion.description;
+    msg = "".concat(msg, " (\"").concat(assertion.output, "\"");
+    msg = "".concat(msg, " ").concat(assertion.assertionType, " \"").concat(assertion.expected, "\"");
+    if (assertion.details) {
+        msg = "".concat(msg, " -- ").concat(assertion.details);
+    }
+    msg = "".concat(msg, ")");
+    msg = "".concat(msg, "\n").concat(chalk.green('+ expected ')).concat(chalk.red('- actual'));
+    msg = "".concat(msg, "\n\n").concat(chalk.red("-".concat(assertion.output)));
+    msg = "".concat(msg, "\n").concat(chalk.green("+".concat(assertion.expected, "\n")));
+    return msg;
+}
+exports.formatFailureMessage = formatFailureMessage;
+function dealWithAnnoyingMediaQueries(rawCSS) {
+    var matchMediaQuery = /(@[a-zA-Z0-9:()\s-]+)/g;
+    // eslint-disable-next-line max-len
+    var matchCSSWithinMediaQueryBlock = /@[a-zA-Z0-9:()\s-]+{([a-zA-Z0-9:()\s-;._\\n{}]+)(?!}\\n})/g;
+    var mediaqueries = rawCSS.match(matchMediaQuery);
+    var rawCSSSansMediaQueries = rawCSS
+        .replace(matchMediaQuery, '')
+        .replace(matchCSSWithinMediaQueryBlock, '')
+        .replace(/^{/, '');
+    var matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
+    var i = 0;
+    var mediaQueryBasedSelectors = [];
+    var mediaqueryRule = /* istanbul ignore next */ function (rule) {
+        return mediaqueries[i] + rule;
+    };
+    /* istanbul ignore next */
+    while (matches !== null) {
+        // This is necessary to avoid infinite loops with zero-width matches
+        if (matches.index === matchCSSWithinMediaQueryBlock.lastIndex) {
+            matchCSSWithinMediaQueryBlock.lastIndex++;
+        }
+        /* istanbul ignore next */
+        var cssWithinMediaQuery = (0, utils_1.removeNewLines)(matches[1]);
+        var cssRules = (0, utils_1.cssStringToArrayOfRules)(cssWithinMediaQuery);
+        mediaQueryBasedSelectors = mediaQueryBasedSelectors.concat(cssRules.map(mediaqueryRule));
+        i++;
+        matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
+    }
+    return {
+        mediaQueryBasedSelectors: mediaQueryBasedSelectors,
+        rawCSSSansMediaQueries: rawCSSSansMediaQueries,
+    };
+}
+function createSelectorsRulesPairs(cssString) {
+    var processedMediaQueries = dealWithAnnoyingMediaQueries(cssString);
+    var mediaQueries = (0, utils_1.splitSelectorAndProperties)(processedMediaQueries.mediaQueryBasedSelectors);
+    var nonMediaQueries = processedMediaQueries.rawCSSSansMediaQueries;
+    var blocks = (0, utils_1.cssStringToArrayOfRules)(nonMediaQueries);
+    var splitBlocks = (0, utils_1.splitSelectorAndProperties)(blocks);
+    return splitBlocks.concat(mediaQueries).filter(utils_1.falsyValues);
+}
+function contains(output, expected) {
+    var outputBlocks = createSelectorsRulesPairs(output);
+    var expectedBlocks = createSelectorsRulesPairs(expected);
+    var results = expectedBlocks.map(function (block) {
+        var outputBlock = outputBlocks.find(function (element) { return element.selector === block.selector; });
+        if (outputBlock) {
+            // Turns a css string into an array of property-value pairs.
+            var expectedProperties = block.output
+                .split(';')
+                .map(function (propertyValuePair) { return propertyValuePair.trim(); })
+                .filter(function (innerBlock) { return innerBlock !== ' {' && innerBlock !== '}'; });
+            // This is the assertion itself!
+            return expectedProperties.every(function (property) {
+                return outputBlock.output.includes(property);
+            });
+        }
+        return false;
+    });
+    return results.every(function (result) { return result === true; });
+}
+function finishCurrentAssertion(ctx) {
+    if (ctx.currentAssertion) {
+        ctx.currentTest.assertions.push(ctx.currentAssertion);
+        delete ctx.currentAssertion;
+    }
+}
+function finishCurrentTest(ctx) {
+    finishCurrentAssertion(ctx);
+    if (ctx.currentTest) {
+        ctx.currentModule.tests.push(ctx.currentTest);
+        delete ctx.currentTest;
+    }
+}
+function insertModule(paths, module, ctx) {
+    if (!ctx.modules) {
+        ctx.modules = [];
+    }
+    if (paths.length > 1) {
+        var newCtx = (0, lodash_1.find)(ctx.modules, { module: paths[0] });
+        if (!newCtx) {
+            newCtx = { module: paths[0] };
+            ctx.modules.push(newCtx);
+        }
+        insertModule(paths.slice(1), module, newCtx);
+    }
+    else {
+        ctx.modules.push(module);
+    }
+}
+function finishCurrentModule(ctx) {
+    finishCurrentTest(ctx);
+    if (ctx.currentModule) {
+        var paths = ctx.currentModule.module.split(constants_1.MODULE_NESTING_TOKEN);
+        ctx.currentModule.module = (0, lodash_1.last)(paths);
+        insertModule(paths, ctx.currentModule, ctx);
+        delete ctx.currentModule;
+    }
+}
+function describeModule(module, describe, it) {
+    describe(module.module, function () {
+        (0, lodash_1.forEach)(module.modules, function (submodule) {
+            describeModule(submodule, describe, it);
+        });
+        (0, lodash_1.forEach)(module.tests, function (test) {
+            it(test.test, function () {
+                (0, lodash_1.forEach)(test.assertions, function (assertion) {
+                    if (!assertion.passed) {
+                        assert.fail(formatFailureMessage(assertion));
+                    }
+                });
+            });
+        });
+    });
+}
+function runSass(sassOptions, trueOptions) {
+    var sassOpts = Object.assign({}, sassOptions);
+    var trueOpts = Object.assign({}, trueOptions);
+    var sassPath = path.join(__dirname, '..', 'sass');
+    if (sassOpts.includePaths) {
+        sassOpts.includePaths.push(sassPath);
+    }
+    else {
+        sassOpts.includePaths = [sassPath];
+    }
+    var sass;
+    if (trueOpts.sass) {
+        sass = trueOpts.sass;
+    }
+    else {
+        // eslint-disable-next-line global-require
+        sass = require('sass');
+    }
+    // eslint-disable-next-line no-sync
+    var parsedCss = sass.renderSync(sassOpts).css.toString();
+    var modules = parse(parsedCss, trueOpts.contextLines);
+    (0, lodash_1.forEach)(modules, function (module) {
+        describeModule(module, trueOpts.describe, trueOpts.it);
+    });
+}
+exports.runSass = runSass;
+function parse(rawCss, ctxLines) {
+    var contextLines = typeof ctxLines === 'undefined' ? 10 : ctxLines;
+    var lines = rawCss.split(/\r?\n/);
+    function parseModule(rule, ctx) {
+        if (rule.type === 'comment') {
+            var text = rule.comment.trim();
+            if (!text) {
+                return parseModule;
+            }
+            if ((0, utils_1.startsWith)(text, constants_1.MODULE_TOKEN)) {
+                finishCurrentModule(ctx);
+                ctx.currentModule = {
+                    module: text.substring(constants_1.MODULE_TOKEN.length),
+                    tests: [],
+                };
+                return parseTest;
+            }
+            if ((0, utils_1.startsWith)(text, constants_1.SUMMARY_TOKEN)) {
+                return ignoreUntilEndSummary;
+            }
+            // ignore un-recognized comments, keep looking for module header.
+            return parseModule;
+        }
+        // ignore other rule types
+        return parseModule;
+    }
+    function parseCss() {
+        var ast = css.parse(rawCss);
+        var ctx = { modules: [] };
+        var handler = parseModule;
+        (0, lodash_1.forEach)(ast.stylesheet.rules, function (rule) {
+            handler = handler(rule, ctx);
+        });
+        finishCurrentModule(ctx);
+        return ctx.modules;
+    }
+    function parseError(msg, seeking, pos) {
+        var errorMsg = "Line ".concat(pos.start.line, ", ") +
+            "column ".concat(pos.start.column, ": ").concat(msg, "; ") +
+            "looking for ".concat(seeking, ".\n") +
+            "-- Context --\n".concat(lines
+                .slice(Math.max(0, pos.start.line - contextLines), pos.start.line)
+                .join('\n'), "\n").concat(' '.repeat(pos.start.column - 1), "^\n");
+        return new Error(errorMsg);
+    }
+    var ignoreUntilEndSummary = function (rule) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if ((0, utils_1.startsWith)(text, constants_1.END_SUMMARY_TOKEN)) {
+                return parseModule;
+            }
+            return ignoreUntilEndSummary;
+        }
+        throw parseError("Unexpected rule type \"".concat(rule.type, "\""), 'end summary', rule.position);
+    };
+    var parseTest = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if (!text) {
+                return parseTest;
+            }
+            if (text.match(/^-+$/)) {
+                return parseTest;
+            }
+            if ((0, utils_1.startsWith)(text, constants_1.TEST_TOKEN)) {
+                finishCurrentTest(ctx);
+                ctx.currentTest = {
+                    test: text.substring(constants_1.TEST_TOKEN.length),
+                    assertions: [],
+                };
+                return parseAssertion;
+            }
+            return parseModule(rule, ctx);
+        }
+        // ignore other rule types
+        return parseModule;
+    };
+    var parseAssertion = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trimStart();
+            if (!text) {
+                return parseAssertion;
+            }
+            if ((0, utils_1.startsWith)(text, constants_1.PASS_TOKEN)) {
+                finishCurrentAssertion(ctx);
+                ctx.currentAssertion = {
+                    description: text.substring(constants_1.PASS_TOKEN.length).trim() || '<no description>',
+                    passed: true,
+                };
+                return parseAssertion;
+            }
+            else if ((0, utils_1.startsWith)(text, constants_1.FAIL_TOKEN)) {
+                finishCurrentAssertion(ctx);
+                var endAssertionType = text.indexOf(constants_1.END_FAIL_TOKEN);
+                ctx.currentAssertion = {
+                    description: text.substring(endAssertionType + 2).trim(),
+                    passed: false,
+                    assertionType: text
+                        .substring(constants_1.FAIL_TOKEN.length, endAssertionType)
+                        .trim(),
+                };
+                return parseFailureDetail;
+            }
+            else if ((0, utils_1.startsWith)(text, constants_1.ASSERT_TOKEN)) {
+                finishCurrentAssertion(ctx);
+                ctx.currentAssertion = {
+                    description: text.substring(constants_1.ASSERT_TOKEN.length).trim(),
+                    assertionType: 'equal',
+                };
+                return parseAssertionOutputStart;
+            }
+            return parseTest(rule, ctx);
+        }
+        // ignore other rule types
+        return parseModule;
+    };
+    var parseFailureDetail = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if ((0, utils_1.startsWith)(text, constants_1.FAILURE_DETAIL_TOKEN)) {
+                var detail = text.substring(constants_1.FAILURE_DETAIL_TOKEN.length);
+                var outputOrExpected = void 0;
+                if ((0, utils_1.startsWith)(detail, constants_1.OUTPUT_TOKEN)) {
+                    outputOrExpected = 'output';
+                }
+                else if ((0, utils_1.startsWith)(detail, constants_1.EXPECTED_TOKEN)) {
+                    outputOrExpected = 'expected';
+                }
+                if (outputOrExpected) {
+                    var startType = text.indexOf(constants_1.FAILURE_TYPE_START_TOKEN);
+                    var endType = text.indexOf(constants_1.FAILURE_TYPE_END_TOKEN);
+                    var type = text.substring(startType, endType + 1);
+                    var content = text.substring(endType + 2);
+                    ctx.currentAssertion[outputOrExpected] = "".concat(type, " ").concat(content);
+                    return parseFailureDetail;
+                }
+                var splitAt = detail.indexOf(constants_1.DETAILS_SEPARATOR_TOKEN);
+                if (splitAt !== -1) {
+                    var key = detail.substring(0, splitAt);
+                    ctx.currentAssertion[key.toLowerCase()] = detail.substring(splitAt + constants_1.DETAILS_SEPARATOR_TOKEN.length);
+                    return parseFailureDetail;
+                }
+            }
+            return parseAssertion(rule, ctx);
+        }
+        throw parseError("Unexpected rule type \"".concat(rule.type, "\""), 'output/expected', rule.position);
+    };
+    var parseAssertionOutputStart = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if (!text) {
+                return parseAssertionOutputStart;
+            }
+            if (text === constants_1.OUTPUT_START_TOKEN) {
+                ctx.currentOutputRules = [];
+                return parseAssertionOutput;
+            }
+            throw parseError("Unexpected comment \"".concat(text, "\""), 'OUTPUT', rule.position);
+        }
+        throw parseError("Unexpected rule type \"".concat(rule.type, "\""), 'OUTPUT', rule.position);
+    };
+    var parseAssertionOutput = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            if (rule.comment.trim() === constants_1.OUTPUT_END_TOKEN) {
+                ctx.currentAssertion.output = css.stringify({
+                    stylesheet: { rules: ctx.currentOutputRules },
+                });
+                delete ctx.currentOutputRules;
+                return parseAssertionExpectedStart;
+            }
+        }
+        ctx.currentOutputRules.push(rule);
+        return parseAssertionOutput;
+    };
+    var parseAssertionExpectedStart = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if (!text) {
+                return parseAssertionExpectedStart;
+            }
+            if (text === constants_1.EXPECTED_START_TOKEN) {
+                ctx.currentExpectedRules = [];
+                return parseAssertionExpected;
+            }
+            if (text === constants_1.CONTAINED_START_TOKEN) {
+                ctx.currentExpectedRules = [];
+                return parseAssertionContained;
+            }
+            throw parseError("Unexpected comment \"".concat(text, "\""), 'EXPECTED', rule.position);
+        }
+        throw parseError("Unexpected rule type \"".concat(rule.type, "\""), 'EXPECTED', rule.position);
+    };
+    var parseAssertionExpected = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            if (rule.comment.trim() === constants_1.EXPECTED_END_TOKEN) {
+                ctx.currentAssertion.expected = css.stringify({
+                    stylesheet: { rules: ctx.currentExpectedRules },
+                });
+                delete ctx.currentExpectedRules;
+                ctx.currentAssertion.passed =
+                    ctx.currentAssertion.output === ctx.currentAssertion.expected;
+                return parseEndAssertion;
+            }
+        }
+        ctx.currentExpectedRules.push(rule);
+        return parseAssertionExpected;
+    };
+    var parseEndAssertion = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            var text = rule.comment.trim();
+            if (!text) {
+                return parseEndAssertion;
+            }
+            if (text === constants_1.ASSERT_END_TOKEN) {
+                finishCurrentAssertion(ctx);
+                return parseAssertion;
+            }
+            throw parseError("Unexpected comment \"".concat(text, "\""), 'END_ASSERT', rule.position);
+        }
+        throw parseError("Unexpected rule type \"".concat(rule.type, "\""), 'END_ASSERT', rule.position);
+    };
+    var parseAssertionContained = function (rule, ctx) {
+        if ((0, utils_1.isCommentNode)(rule)) {
+            if (rule.comment.trim() === constants_1.CONTAINED_END_TOKEN) {
+                ctx.currentAssertion.expected = css.stringify({
+                    stylesheet: { rules: ctx.currentExpectedRules },
+                });
+                delete ctx.currentExpectedRules;
+                ctx.currentAssertion.passed = contains(ctx.currentAssertion.output, ctx.currentAssertion.expected);
+                return parseEndAssertion;
+            }
+        }
+        ctx.currentExpectedRules.push(rule);
+        return parseAssertionContained;
+    };
+    return parseCss();
+}
+exports.parse = parse;
+//# sourceMappingURL=index.js.map
\ No newline at end of file
diff --git a/lib/index.js.map b/lib/index.js.map
new file mode 100644
index 0000000..19bdff3
--- /dev/null
+++ b/lib/index.js.map
@@ -0,0 +1 @@
+{"version":3,"file":"index.js","sourceRoot":"","sources":["../src/index.ts"],"names":[],"mappings":";AAAA,8EAA8E;;;AAE9E,2BAA6B;AAC7B,+BAAiC;AAGjC,yBAA2B;AAC3B,iCAA6C;AAE7C,6BAA+B;AAE/B,yCAuBqB;AACrB,iCAOiB;AAsCjB,SAAgB,oBAAoB,CAAC,SAAoB;IACvD,IAAI,GAAG,GAAG,SAAS,CAAC,WAAW,CAAC;IAChC,GAAG,GAAG,UAAG,GAAG,iBAAM,SAAS,CAAC,MAAM,OAAG,CAAC;IACtC,GAAG,GAAG,UAAG,GAAG,cAAI,SAAS,CAAC,aAAa,gBAAK,SAAS,CAAC,QAAQ,OAAG,CAAC;IAClE,IAAI,SAAS,CAAC,OAAO,EAAE;QACrB,GAAG,GAAG,UAAG,GAAG,iBAAO,SAAS,CAAC,OAAO,CAAE,CAAC;KACxC;IACD,GAAG,GAAG,UAAG,GAAG,MAAG,CAAC;IAChB,GAAG,GAAG,UAAG,GAAG,eAAK,KAAK,CAAC,KAAK,CAAC,aAAa,CAAC,SAAG,KAAK,CAAC,GAAG,CAAC,UAAU,CAAC,CAAE,CAAC;IACtE,GAAG,GAAG,UAAG,GAAG,iBAAO,KAAK,CAAC,GAAG,CAAC,WAAI,SAAS,CAAC,MAAM,CAAE,CAAC,CAAE,CAAC;IACvD,GAAG,GAAG,UAAG,GAAG,eAAK,KAAK,CAAC,KAAK,CAAC,WAAI,SAAS,CAAC,QAAQ,OAAI,CAAC,CAAE,CAAC;IAC3D,OAAO,GAAG,CAAC;AACb,CAAC;AAZD,oDAYC;AAED,SAAS,4BAA4B,CAAC,MAAc;IAClD,IAAM,eAAe,GAAG,wBAAwB,CAAC;IACjD,mCAAmC;IACnC,IAAM,6BAA6B,GAAG,4DAA4D,CAAC;IAEnG,IAAM,YAAY,GAAG,MAAM,CAAC,KAAK,CAAC,eAAe,CAAC,CAAC;IACnD,IAAM,sBAAsB,GAAG,MAAM;SAClC,OAAO,CAAC,eAAe,EAAE,EAAE,CAAC;SAC5B,OAAO,CAAC,6BAA6B,EAAE,EAAE,CAAC;SAC1C,OAAO,CAAC,IAAI,EAAE,EAAE,CAAC,CAAC;IACrB,IAAI,OAAO,GAAG,6BAA6B,CAAC,IAAI,CAAC,MAAM,CAAC,CAAC;IACzD,IAAI,CAAC,GAAG,CAAC,CAAC;IACV,IAAI,wBAAwB,GAAG,EAAE,CAAC;IAClC,IAAM,cAAc,GAAG,0BAA0B,CAAC,UAAC,IAAI;QACrD,OAAA,YAAY,CAAC,CAAC,CAAC,GAAG,IAAI;IAAtB,CAAsB,CAAC;IACzB,0BAA0B;IAC1B,OAAO,OAAO,KAAK,IAAI,EAAE;QACvB,oEAAoE;QACpE,IAAI,OAAO,CAAC,KAAK,KAAK,6BAA6B,CAAC,SAAS,EAAE;YAC7D,6BAA6B,CAAC,SAAS,EAAE,CAAC;SAC3C;QAED,0BAA0B;QAC1B,IAAM,mBAAmB,GAAG,IAAA,sBAAc,EAAC,OAAO,CAAC,CAAC,CAAC,CAAC,CAAC;QACvD,IAAM,QAAQ,GAAG,IAAA,+BAAuB,EAAC,mBAAmB,CAAC,CAAC;QAE9D,wBAAwB,GAAG,wBAAwB,CAAC,MAAM,CACxD,QAAQ,CAAC,GAAG,CAAC,cAAc,CAAC,CAC7B,CAAC;QAEF,CAAC,EAAE,CAAC;QACJ,OAAO,GAAG,6BAA6B,CAAC,IAAI,CAAC,MAAM,CAAC,CAAC;KACtD;IAED,OAAO;QACL,wBAAwB,0BAAA;QACxB,sBAAsB,wBAAA;KACvB,CAAC;AACJ,CAAC;AAED,SAAS,yBAAyB,CAAC,SAAiB;IAClD,IAAM,qBAAqB,GAAG,4BAA4B,CAAC,SAAS,CAAC,CAAC;IACtE,IAAM,YAAY,GAAG,IAAA,kCAA0B,EAC7C,qBAAqB,CAAC,wBAAwB,CAC/C,CAAC;IACF,IAAM,eAAe,GAAG,qBAAqB,CAAC,sBAAsB,CAAC;IAErE,IAAM,MAAM,GAAG,IAAA,+BAAuB,EAAC,eAAe,CAAC,CAAC;IAExD,IAAM,WAAW,GAAG,IAAA,kCAA0B,EAAC,MAAM,CAAC,CAAC;IAEvD,OAAO,WAAW,CAAC,MAAM,CAAC,YAAY,CAAC,CAAC,MAAM,CAAC,mBAAW,CAAC,CAAC;AAC9D,CAAC;AAED,SAAS,QAAQ,CAAC,MAAM,EAAE,QAAQ;IAChC,IAAM,YAAY,GAAG,yBAAyB,CAAC,MAAM,CAAC,CAAC;IACvD,IAAM,cAAc,GAAG,yBAAyB,CAAC,QAAQ,CAAC,CAAC;IAE3D,IAAM,OAAO,GAAG,cAAc,CAAC,GAAG,CAAC,UAAC,KAAK;QACvC,IAAM,WAAW,GAAG,YAAY,CAAC,IAAI,CACnC,UAAC,OAAO,IAAK,OAAA,OAAO,CAAC,QAAQ,KAAK,KAAK,CAAC,QAAQ,EAAnC,CAAmC,CACjD,CAAC;QACF,IAAI,WAAW,EAAE;YACf,4DAA4D;YAC5D,IAAM,kBAAkB,GAAG,KAAK,CAAC,MAAM;iBACpC,KAAK,CAAC,GAAG,CAAC;iBACV,GAAG,CAAC,UAAC,iBAAiB,IAAK,OAAA,iBAAiB,CAAC,IAAI,EAAE,EAAxB,CAAwB,CAAC;iBACpD,MAAM,CAAC,UAAC,UAAU,IAAK,OAAA,UAAU,KAAK,IAAI,IAAI,UAAU,KAAK,GAAG,EAAzC,CAAyC,CAAC,CAAC;YAErE,gCAAgC;YAChC,OAAO,kBAAkB,CAAC,KAAK,CAAC,UAAC,QAAQ;gBACvC,OAAA,WAAW,CAAC,MAAM,CAAC,QAAQ,CAAC,QAAQ,CAAC;YAArC,CAAqC,CACtC,CAAC;SACH;QACD,OAAO,KAAK,CAAC;IACf,CAAC,CAAC,CAAC;IAEH,OAAO,OAAO,CAAC,KAAK,CAAC,UAAC,MAAM,IAAK,OAAA,MAAM,KAAK,IAAI,EAAf,CAAe,CAAC,CAAC;AACpD,CAAC;AAED,SAAS,sBAAsB,CAAC,GAAY;IAC1C,IAAI,GAAG,CAAC,gBAAgB,EAAE;QACxB,GAAG,CAAC,WAAW,CAAC,UAAU,CAAC,IAAI,CAAC,GAAG,CAAC,gBAAgB,CAAC,CAAC;QACtD,OAAO,GAAG,CAAC,gBAAgB,CAAC;KAC7B;AACH,CAAC;AAED,SAAS,iBAAiB,CAAC,GAAY;IACrC,sBAAsB,CAAC,GAAG,CAAC,CAAC;IAC5B,IAAI,GAAG,CAAC,WAAW,EAAE;QACnB,GAAG,CAAC,aAAa,CAAC,KAAK,CAAC,IAAI,CAAC,GAAG,CAAC,WAAW,CAAC,CAAC;QAC9C,OAAO,GAAG,CAAC,WAAW,CAAC;KACxB;AACH,CAAC;AAED,SAAS,YAAY,CAAC,KAAe,EAAE,MAAc,EAAE,GAAY;IACjE,IAAI,CAAC,GAAG,CAAC,OAAO,EAAE;QAChB,GAAG,CAAC,OAAO,GAAG,EAAE,CAAC;KAClB;IAED,IAAI,KAAK,CAAC,MAAM,GAAG,CAAC,EAAE;QACpB,IAAI,MAAM,GAAG,IAAA,aAAI,EAAC,GAAG,CAAC,OAAO,EAAE,EAAE,MAAM,EAAE,KAAK,CAAC,CAAC,CAAC,EAAE,CAAC,CAAC;QACrD,IAAI,CAAC,MAAM,EAAE;YACX,MAAM,GAAG,EAAE,MAAM,EAAE,KAAK,CAAC,CAAC,CAAC,EAAE,CAAC;YAC9B,GAAG,CAAC,OAAO,CAAC,IAAI,CAAC,MAAM,CAAC,CAAC;SAC1B;QACD,YAAY,CAAC,KAAK,CAAC,KAAK,CAAC,CAAC,CAAC,EAAE,MAAM,EAAE,MAAM,CAAC,CAAC;KAC9C;SAAM;QACL,GAAG,CAAC,OAAO,CAAC,IAAI,CAAC,MAAM,CAAC,CAAC;KAC1B;AACH,CAAC;AAED,SAAS,mBAAmB,CAAC,GAAY;IACvC,iBAAiB,CAAC,GAAG,CAAC,CAAC;IACvB,IAAI,GAAG,CAAC,aAAa,EAAE;QACrB,IAAM,KAAK,GAAG,GAAG,CAAC,aAAa,CAAC,MAAM,CAAC,KAAK,CAAC,gCAAoB,CAAC,CAAC;QACnE,GAAG,CAAC,aAAa,CAAC,MAAM,GAAG,IAAA,aAAI,EAAC,KAAK,CAAC,CAAC;QACvC,YAAY,CAAC,KAAK,EAAE,GAAG,CAAC,aAAa,EAAE,GAAG,CAAC,CAAC;QAC5C,OAAO,GAAG,CAAC,aAAa,CAAC;KAC1B;AACH,CAAC;AAED,SAAS,cAAc,CACrB,MAAc,EACd,QAAiC,EACjC,EAAqB;IAErB,QAAQ,CAAC,MAAM,CAAC,MAAM,EAAE;QACtB,IAAA,gBAAO,EAAC,MAAM,CAAC,OAAO,EAAE,UAAC,SAAS;YAChC,cAAc,CAAC,SAAS,EAAE,QAAQ,EAAE,EAAE,CAAC,CAAC;QAC1C,CAAC,CAAC,CAAC;QACH,IAAA,gBAAO,EAAC,MAAM,CAAC,KAAK,EAAE,UAAC,IAAI;YACzB,EAAE,CAAC,IAAI,CAAC,IAAI,EAAE;gBACZ,IAAA,gBAAO,EAAC,IAAI,CAAC,UAAU,EAAE,UAAC,SAAS;oBACjC,IAAI,CAAC,SAAS,CAAC,MAAM,EAAE;wBACrB,MAAM,CAAC,IAAI,CAAC,oBAAoB,CAAC,SAAS,CAAC,CAAC,CAAC;qBAC9C;gBACH,CAAC,CAAC,CAAC;YACL,CAAC,CAAC,CAAC;QACL,CAAC,CAAC,CAAC;IACL,CAAC,CAAC,CAAC;AACL,CAAC;AAED,SAAgB,OAAO,CAAC,WAAoB,EAAE,WAAwB;IACpE,IAAM,QAAQ,GAAG,MAAM,CAAC,MAAM,CAAC,EAAE,EAAE,WAAW,CAAC,CAAC;IAChD,IAAM,QAAQ,GAAG,MAAM,CAAC,MAAM,CAAC,EAAE,EAAE,WAAW,CAAC,CAAC;IAChD,IAAM,QAAQ,GAAG,IAAI,CAAC,IAAI,CAAC,SAAS,EAAE,IAAI,EAAE,MAAM,CAAC,CAAC;IACpD,IAAI,QAAQ,CAAC,YAAY,EAAE;QACzB,QAAQ,CAAC,YAAY,CAAC,IAAI,CAAC,QAAQ,CAAC,CAAC;KACtC;SAAM;QACL,QAAQ,CAAC,YAAY,GAAG,CAAC,QAAQ,CAAC,CAAC;KACpC;IAED,IAAI,IAAI,CAAC;IACT,IAAI,QAAQ,CAAC,IAAI,EAAE;QACjB,IAAI,GAAG,QAAQ,CAAC,IAAI,CAAC;KACtB;SAAM;QACL,0CAA0C;QAC1C,IAAI,GAAG,OAAO,CAAC,MAAM,CAAC,CAAC;KACxB;IAED,mCAAmC;IACnC,IAAM,SAAS,GAAG,IAAI,CAAC,UAAU,CAAC,QAAQ,CAAC,CAAC,GAAG,CAAC,QAAQ,EAAE,CAAC;IAC3D,IAAM,OAAO,GAAG,KAAK,CAAC,SAAS,EAAE,QAAQ,CAAC,YAAY,CAAC,CAAC;IAExD,IAAA,gBAAO,EAAC,OAAO,EAAE,UAAC,MAAM;QACtB,cAAc,CAAC,MAAM,EAAE,QAAQ,CAAC,QAAQ,EAAE,QAAQ,CAAC,EAAE,CAAC,CAAC;IACzD,CAAC,CAAC,CAAC;AACL,CAAC;AAzBD,0BAyBC;AAED,SAAgB,KAAK,CACnB,MAAwB,EACxB,QAA2B;IAE3B,IAAM,YAAY,GAAG,OAAO,QAAQ,KAAK,WAAW,CAAC,CAAC,CAAC,EAAE,CAAC,CAAC,CAAC,QAAQ,CAAC;IACrE,IAAM,KAAK,GAAG,MAAM,CAAC,KAAK,CAAC,OAAO,CAAC,CAAC;IAEpC,SAAS,WAAW,CAAC,IAAa,EAAE,GAAY;QAC9C,IAAI,IAAI,CAAC,IAAI,KAAK,SAAS,EAAE;YAC3B,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,WAAW,CAAC;aACpB;YACD,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,wBAAY,CAAC,EAAE;gBAClC,mBAAmB,CAAC,GAAG,CAAC,CAAC;gBACzB,GAAG,CAAC,aAAa,GAAG;oBAClB,MAAM,EAAE,IAAI,CAAC,SAAS,CAAC,wBAAY,CAAC,MAAM,CAAC;oBAC3C,KAAK,EAAE,EAAE;iBACV,CAAC;gBACF,OAAO,SAAS,CAAC;aAClB;YACD,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,yBAAa,CAAC,EAAE;gBACnC,OAAO,qBAAqB,CAAC;aAC9B;YACD,iEAAiE;YACjE,OAAO,WAAW,CAAC;SACpB;QACD,0BAA0B;QAC1B,OAAO,WAAW,CAAC;IACrB,CAAC;IAED,SAAS,QAAQ;QACf,IAAM,GAAG,GAAG,GAAG,CAAC,KAAK,CAAC,MAAM,CAAC,CAAC;QAC9B,IAAM,GAAG,GAAY,EAAE,OAAO,EAAE,EAAE,EAAE,CAAC;QACrC,IAAI,OAAO,GAAG,WAAW,CAAC;QAE1B,IAAA,gBAAO,EAAC,GAAG,CAAC,UAAU,CAAC,KAAK,EAAE,UAAC,IAAI;YACjC,OAAO,GAAG,OAAO,CAAC,IAAI,EAAE,GAAG,CAAC,CAAC;QAC/B,CAAC,CAAC,CAAC;QAEH,mBAAmB,CAAC,GAAG,CAAC,CAAC;QAEzB,OAAO,GAAG,CAAC,OAAO,CAAC;IACrB,CAAC;IAED,SAAS,UAAU,CAAC,GAAW,EAAE,OAAe,EAAE,GAAqB;QACrE,IAAM,QAAQ,GACZ,eAAQ,GAAG,CAAC,KAAK,CAAC,IAAI,OAAI;YAC1B,iBAAU,GAAG,CAAC,KAAK,CAAC,MAAM,eAAK,GAAG,OAAI;YACtC,sBAAe,OAAO,QAAK;YAC3B,yBAAkB,KAAK;iBACpB,KAAK,CAAC,IAAI,CAAC,GAAG,CAAC,CAAC,EAAE,GAAG,CAAC,KAAK,CAAC,IAAI,GAAG,YAAY,CAAC,EAAE,GAAG,CAAC,KAAK,CAAC,IAAI,CAAC;iBACjE,IAAI,CAAC,IAAI,CAAC,eAAK,GAAG,CAAC,MAAM,CAAC,GAAG,CAAC,KAAK,CAAC,MAAM,GAAG,CAAC,CAAC,QAAK,CAAC;QAC1D,OAAO,IAAI,KAAK,CAAC,QAAQ,CAAC,CAAC;IAC7B,CAAC;IAED,IAAM,qBAAqB,GAAG,UAAC,IAAU;QACvC,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,6BAAiB,CAAC,EAAE;gBACvC,OAAO,WAAW,CAAC;aACpB;YACD,OAAO,qBAAqB,CAAC;SAC9B;QACD,MAAM,UAAU,CACd,iCAAyB,IAAI,CAAC,IAAI,OAAG,EACrC,aAAa,EACb,IAAI,CAAC,QAAQ,CACd,CAAC;IACJ,CAAC,CAAC;IAEF,IAAM,SAAS,GAAG,UAAC,IAAU,EAAE,GAAY;QACzC,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,SAAS,CAAC;aAClB;YACD,IAAI,IAAI,CAAC,KAAK,CAAC,MAAM,CAAC,EAAE;gBACtB,OAAO,SAAS,CAAC;aAClB;YACD,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,sBAAU,CAAC,EAAE;gBAChC,iBAAiB,CAAC,GAAG,CAAC,CAAC;gBACvB,GAAG,CAAC,WAAW,GAAG;oBAChB,IAAI,EAAE,IAAI,CAAC,SAAS,CAAC,sBAAU,CAAC,MAAM,CAAC;oBACvC,UAAU,EAAE,EAAE;iBACf,CAAC;gBACF,OAAO,cAAc,CAAC;aACvB;YACD,OAAO,WAAW,CAAC,IAAI,EAAE,GAAG,CAAC,CAAC;SAC/B;QACD,0BAA0B;QAC1B,OAAO,WAAW,CAAC;IACrB,CAAC,CAAC;IAEF,IAAM,cAAc,GAAG,UAAC,IAAU,EAAE,GAAY;QAC9C,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,SAAS,EAAE,CAAC;YACtC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,cAAc,CAAC;aACvB;YACD,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,sBAAU,CAAC,EAAE;gBAChC,sBAAsB,CAAC,GAAG,CAAC,CAAC;gBAC5B,GAAG,CAAC,gBAAgB,GAAG;oBACrB,WAAW,EACT,IAAI,CAAC,SAAS,CAAC,sBAAU,CAAC,MAAM,CAAC,CAAC,IAAI,EAAE,IAAI,kBAAkB;oBAChE,MAAM,EAAE,IAAI;iBACb,CAAC;gBACF,OAAO,cAAc,CAAC;aACvB;iBAAM,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,sBAAU,CAAC,EAAE;gBACvC,sBAAsB,CAAC,GAAG,CAAC,CAAC;gBAC5B,IAAM,gBAAgB,GAAG,IAAI,CAAC,OAAO,CAAC,0BAAc,CAAC,CAAC;gBACtD,GAAG,CAAC,gBAAgB,GAAG;oBACrB,WAAW,EAAE,IAAI,CAAC,SAAS,CAAC,gBAAgB,GAAG,CAAC,CAAC,CAAC,IAAI,EAAE;oBACxD,MAAM,EAAE,KAAK;oBACb,aAAa,EAAE,IAAI;yBAChB,SAAS,CAAC,sBAAU,CAAC,MAAM,EAAE,gBAAgB,CAAC;yBAC9C,IAAI,EAAE;iBACV,CAAC;gBACF,OAAO,kBAAkB,CAAC;aAC3B;iBAAM,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,wBAAY,CAAC,EAAE;gBACzC,sBAAsB,CAAC,GAAG,CAAC,CAAC;gBAC5B,GAAG,CAAC,gBAAgB,GAAG;oBACrB,WAAW,EAAE,IAAI,CAAC,SAAS,CAAC,wBAAY,CAAC,MAAM,CAAC,CAAC,IAAI,EAAE;oBACvD,aAAa,EAAE,OAAO;iBACvB,CAAC;gBACF,OAAO,yBAAyB,CAAC;aAClC;YACD,OAAO,SAAS,CAAC,IAAI,EAAE,GAAG,CAAC,CAAC;SAC7B;QACD,0BAA0B;QAC1B,OAAO,WAAW,CAAC;IACrB,CAAC,CAAC;IAEF,IAAM,kBAAkB,GAAG,UAAC,IAAU,EAAE,GAAY;QAClD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,IAAA,kBAAU,EAAC,IAAI,EAAE,gCAAoB,CAAC,EAAE;gBAC1C,IAAM,MAAM,GAAG,IAAI,CAAC,SAAS,CAAC,gCAAoB,CAAC,MAAM,CAAC,CAAC;gBAC3D,IAAI,gBAAgB,SAAA,CAAC;gBACrB,IAAI,IAAA,kBAAU,EAAC,MAAM,EAAE,wBAAY,CAAC,EAAE;oBACpC,gBAAgB,GAAG,QAAQ,CAAC;iBAC7B;qBAAM,IAAI,IAAA,kBAAU,EAAC,MAAM,EAAE,0BAAc,CAAC,EAAE;oBAC7C,gBAAgB,GAAG,UAAU,CAAC;iBAC/B;gBACD,IAAI,gBAAgB,EAAE;oBACpB,IAAM,SAAS,GAAG,IAAI,CAAC,OAAO,CAAC,oCAAwB,CAAC,CAAC;oBACzD,IAAM,OAAO,GAAG,IAAI,CAAC,OAAO,CAAC,kCAAsB,CAAC,CAAC;oBACrD,IAAM,IAAI,GAAG,IAAI,CAAC,SAAS,CAAC,SAAS,EAAE,OAAO,GAAG,CAAC,CAAC,CAAC;oBACpD,IAAM,OAAO,GAAG,IAAI,CAAC,SAAS,CAAC,OAAO,GAAG,CAAC,CAAC,CAAC;oBAC5C,GAAG,CAAC,gBAAgB,CAAC,gBAAgB,CAAC,GAAG,UAAG,IAAI,cAAI,OAAO,CAAE,CAAC;oBAC9D,OAAO,kBAAkB,CAAC;iBAC3B;gBACD,IAAM,OAAO,GAAG,MAAM,CAAC,OAAO,CAAC,mCAAuB,CAAC,CAAC;gBACxD,IAAI,OAAO,KAAK,CAAC,CAAC,EAAE;oBAClB,IAAM,GAAG,GAAG,MAAM,CAAC,SAAS,CAAC,CAAC,EAAE,OAAO,CAAC,CAAC;oBACzC,GAAG,CAAC,gBAAgB,CAAC,GAAG,CAAC,WAAW,EAAE,CAAC,GAAG,MAAM,CAAC,SAAS,CACxD,OAAO,GAAG,mCAAuB,CAAC,MAAM,CACzC,CAAC;oBACF,OAAO,kBAAkB,CAAC;iBAC3B;aACF;YACD,OAAO,cAAc,CAAC,IAAI,EAAE,GAAG,CAAC,CAAC;SAClC;QACD,MAAM,UAAU,CACd,iCAAyB,IAAI,CAAC,IAAI,OAAG,EACrC,iBAAiB,EACjB,IAAI,CAAC,QAAQ,CACd,CAAC;IACJ,CAAC,CAAC;IAEF,IAAM,yBAAyB,GAAG,UAAC,IAAU,EAAE,GAAY;QACzD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,yBAAyB,CAAC;aAClC;YACD,IAAI,IAAI,KAAK,8BAAkB,EAAE;gBAC/B,GAAG,CAAC,kBAAkB,GAAG,EAAE,CAAC;gBAC5B,OAAO,oBAAoB,CAAC;aAC7B;YACD,MAAM,UAAU,CAAC,+BAAuB,IAAI,OAAG,EAAE,QAAQ,EAAE,IAAI,CAAC,QAAQ,CAAC,CAAC;SAC3E;QACD,MAAM,UAAU,CACd,iCAAyB,IAAI,CAAC,IAAI,OAAG,EACrC,QAAQ,EACR,IAAI,CAAC,QAAQ,CACd,CAAC;IACJ,CAAC,CAAC;IAEF,IAAM,oBAAoB,GAAG,UAAC,IAAU,EAAE,GAAY;QACpD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAI,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,KAAK,4BAAgB,EAAE;gBAC5C,GAAG,CAAC,gBAAgB,CAAC,MAAM,GAAG,GAAG,CAAC,SAAS,CAAC;oBAC1C,UAAU,EAAE,EAAE,KAAK,EAAE,GAAG,CAAC,kBAAkB,EAAE;iBAC9C,CAAC,CAAC;gBACH,OAAO,GAAG,CAAC,kBAAkB,CAAC;gBAC9B,OAAO,2BAA2B,CAAC;aACpC;SACF;QACD,GAAG,CAAC,kBAAkB,CAAC,IAAI,CAAC,IAAI,CAAC,CAAC;QAClC,OAAO,oBAAoB,CAAC;IAC9B,CAAC,CAAC;IAEF,IAAM,2BAA2B,GAAG,UAAC,IAAU,EAAE,GAAY;QAC3D,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,2BAA2B,CAAC;aACpC;YACD,IAAI,IAAI,KAAK,gCAAoB,EAAE;gBACjC,GAAG,CAAC,oBAAoB,GAAG,EAAE,CAAC;gBAC9B,OAAO,sBAAsB,CAAC;aAC/B;YAED,IAAI,IAAI,KAAK,iCAAqB,EAAE;gBAClC,GAAG,CAAC,oBAAoB,GAAG,EAAE,CAAC;gBAC9B,OAAO,uBAAuB,CAAC;aAChC;YACD,MAAM,UAAU,CACd,+BAAuB,IAAI,OAAG,EAC9B,UAAU,EACV,IAAI,CAAC,QAAQ,CACd,CAAC;SACH;QACD,MAAM,UAAU,CACd,iCAAyB,IAAI,CAAC,IAAI,OAAG,EACrC,UAAU,EACV,IAAI,CAAC,QAAQ,CACd,CAAC;IACJ,CAAC,CAAC;IAEF,IAAM,sBAAsB,GAAG,UAAC,IAAU,EAAE,GAAY;QACtD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAI,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,KAAK,8BAAkB,EAAE;gBAC9C,GAAG,CAAC,gBAAgB,CAAC,QAAQ,GAAG,GAAG,CAAC,SAAS,CAAC;oBAC5C,UAAU,EAAE,EAAE,KAAK,EAAE,GAAG,CAAC,oBAAoB,EAAE;iBAChD,CAAC,CAAC;gBACH,OAAO,GAAG,CAAC,oBAAoB,CAAC;gBAChC,GAAG,CAAC,gBAAgB,CAAC,MAAM;oBACzB,GAAG,CAAC,gBAAgB,CAAC,MAAM,KAAK,GAAG,CAAC,gBAAgB,CAAC,QAAQ,CAAC;gBAChE,OAAO,iBAAiB,CAAC;aAC1B;SACF;QACD,GAAG,CAAC,oBAAoB,CAAC,IAAI,CAAC,IAAI,CAAC,CAAC;QACpC,OAAO,sBAAsB,CAAC;IAChC,CAAC,CAAC;IAEF,IAAM,iBAAiB,GAAG,UAAC,IAAU,EAAE,GAAY;QACjD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAM,IAAI,GAAG,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,CAAC;YACjC,IAAI,CAAC,IAAI,EAAE;gBACT,OAAO,iBAAiB,CAAC;aAC1B;YACD,IAAI,IAAI,KAAK,4BAAgB,EAAE;gBAC7B,sBAAsB,CAAC,GAAG,CAAC,CAAC;gBAC5B,OAAO,cAAc,CAAC;aACvB;YACD,MAAM,UAAU,CACd,+BAAuB,IAAI,OAAG,EAC9B,YAAY,EACZ,IAAI,CAAC,QAAQ,CACd,CAAC;SACH;QACD,MAAM,UAAU,CACd,iCAAyB,IAAI,CAAC,IAAI,OAAG,EACrC,YAAY,EACZ,IAAI,CAAC,QAAQ,CACd,CAAC;IACJ,CAAC,CAAC;IAEF,IAAM,uBAAuB,GAAG,UAAC,IAAU,EAAE,GAAY;QACvD,IAAI,IAAA,qBAAa,EAAC,IAAI,CAAC,EAAE;YACvB,IAAI,IAAI,CAAC,OAAO,CAAC,IAAI,EAAE,KAAK,+BAAmB,EAAE;gBAC/C,GAAG,CAAC,gBAAgB,CAAC,QAAQ,GAAG,GAAG,CAAC,SAAS,CAAC;oBAC5C,UAAU,EAAE,EAAE,KAAK,EAAE,GAAG,CAAC,oBAAoB,EAAE;iBAChD,CAAC,CAAC;gBACH,OAAO,GAAG,CAAC,oBAAoB,CAAC;gBAChC,GAAG,CAAC,gBAAgB,CAAC,MAAM,GAAG,QAAQ,CACpC,GAAG,CAAC,gBAAgB,CAAC,MAAM,EAC3B,GAAG,CAAC,gBAAgB,CAAC,QAAQ,CAC9B,CAAC;gBACF,OAAO,iBAAiB,CAAC;aAC1B;SACF;QACD,GAAG,CAAC,oBAAoB,CAAC,IAAI,CAAC,IAAI,CAAC,CAAC;QACpC,OAAO,uBAAuB,CAAC;IACjC,CAAC,CAAC;IAEF,OAAO,QAAQ,EAAE,CAAC;AACpB,CAAC;AAjSD,sBAiSC"}
\ No newline at end of file
diff --git a/lib/utils.d.ts b/lib/utils.d.ts
new file mode 100644
index 0000000..66820fc
--- /dev/null
+++ b/lib/utils.d.ts
@@ -0,0 +1,10 @@
+import { Comment, Node } from 'css';
+export declare function falsyValues(item?: any): boolean;
+export declare function isCommentNode(node: Node): node is Comment;
+export declare function startsWith(text: string, token: string): boolean;
+export declare function removeNewLines(cssString: string): string;
+export declare function cssStringToArrayOfRules(cssString: string): string[];
+export declare function splitSelectorAndProperties(blocks: string[]): {
+    selector: string;
+    output: string;
+}[];
diff --git a/lib/utils.js b/lib/utils.js
new file mode 100644
index 0000000..8048fd9
--- /dev/null
+++ b/lib/utils.js
@@ -0,0 +1,35 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.splitSelectorAndProperties = exports.cssStringToArrayOfRules = exports.removeNewLines = exports.startsWith = exports.isCommentNode = exports.falsyValues = void 0;
+function falsyValues(item) {
+    return Boolean(item);
+}
+exports.falsyValues = falsyValues;
+function isCommentNode(node) {
+    return node.type === 'comment';
+}
+exports.isCommentNode = isCommentNode;
+function startsWith(text, token) {
+    return text.indexOf(token) === 0;
+}
+exports.startsWith = startsWith;
+function removeNewLines(cssString) {
+    return cssString.replace(/\n/g, '');
+}
+exports.removeNewLines = removeNewLines;
+function cssStringToArrayOfRules(cssString) {
+    return removeNewLines(cssString)
+        .split(/\s*}(?![\s]*["',}])/g)
+        .filter(falsyValues);
+}
+exports.cssStringToArrayOfRules = cssStringToArrayOfRules;
+function splitSelectorAndProperties(blocks) {
+    return blocks.map(function (block) {
+        var temp = block.split('{');
+        var selector = temp[0];
+        var output = temp[1];
+        return { selector: selector, output: output };
+    });
+}
+exports.splitSelectorAndProperties = splitSelectorAndProperties;
+//# sourceMappingURL=utils.js.map
\ No newline at end of file
diff --git a/lib/utils.js.map b/lib/utils.js.map
new file mode 100644
index 0000000..bd5f9a2
--- /dev/null
+++ b/lib/utils.js.map
@@ -0,0 +1 @@
+{"version":3,"file":"utils.js","sourceRoot":"","sources":["../src/utils.ts"],"names":[],"mappings":";;;AAEA,SAAgB,WAAW,CAAC,IAAU;IACpC,OAAO,OAAO,CAAC,IAAI,CAAC,CAAC;AACvB,CAAC;AAFD,kCAEC;AAED,SAAgB,aAAa,CAAC,IAAU;IACtC,OAAO,IAAI,CAAC,IAAI,KAAK,SAAS,CAAC;AACjC,CAAC;AAFD,sCAEC;AAED,SAAgB,UAAU,CAAC,IAAY,EAAE,KAAa;IACpD,OAAO,IAAI,CAAC,OAAO,CAAC,KAAK,CAAC,KAAK,CAAC,CAAC;AACnC,CAAC;AAFD,gCAEC;AAED,SAAgB,cAAc,CAAC,SAAiB;IAC9C,OAAO,SAAS,CAAC,OAAO,CAAC,KAAK,EAAE,EAAE,CAAC,CAAC;AACtC,CAAC;AAFD,wCAEC;AAED,SAAgB,uBAAuB,CAAC,SAAiB;IACvD,OAAO,cAAc,CAAC,SAAS,CAAC;SAC7B,KAAK,CAAC,sBAAsB,CAAC;SAC7B,MAAM,CAAC,WAAW,CAAC,CAAC;AACzB,CAAC;AAJD,0DAIC;AAED,SAAgB,0BAA0B,CAAC,MAAgB;IACzD,OAAO,MAAM,CAAC,GAAG,CAAC,UAAC,KAAK;QACtB,IAAM,IAAI,GAAG,KAAK,CAAC,KAAK,CAAC,GAAG,CAAC,CAAC;QAC9B,IAAM,QAAQ,GAAG,IAAI,CAAC,CAAC,CAAC,CAAC;QACzB,IAAM,MAAM,GAAG,IAAI,CAAC,CAAC,CAAC,CAAC;QACvB,OAAO,EAAE,QAAQ,UAAA,EAAE,MAAM,QAAA,EAAE,CAAC;IAC9B,CAAC,CAAC,CAAC;AACL,CAAC;AAPD,gEAOC"}
\ No newline at end of file
diff --git a/package.json b/package.json
index 788c873..c662a02 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "version": "6.0.1",
   "description": "Unit testing for Sass.",
   "homepage": "https://www.oddbird.net/true/",
-  "main": "lib/main.js",
+  "main": "lib/index.js",
   "repository": {
     "type": "git",
     "url": "https://github.com/oddbird/true.git"
@@ -26,6 +26,12 @@
     "lodash": "^4.17.19"
   },
   "devDependencies": {
+    "@types/chalk": "^2.2.0",
+    "@types/css": "0.0.33",
+    "@types/node": "^16.11.11",
+    "@types/sass": "^1.43.1",
+    "@typescript-eslint/eslint-plugin": "^4.33.0",
+    "@typescript-eslint/parser": "^4.33.0",
     "chai": "^4.1.2",
     "coveralls": "^3.1.0",
     "eslint": "^7.5.0",
@@ -44,7 +50,8 @@
     "stylelint-config-prettier": "^8.0.2",
     "stylelint-config-recommended": "^3.0.0",
     "stylelint-prettier": "^1.1.2",
-    "stylelint-scss": "^3.18.0"
+    "stylelint-scss": "^3.18.0",
+    "typescript": "^4.4.4"
   },
   "eyeglass": {
     "needs": "*",
@@ -53,12 +60,13 @@
     "exports": false
   },
   "scripts": {
+    "build": "tsc",
     "test": "yarn test:mocha; yarn test:jest",
     "test:mocha": "nyc --reporter=html --reporter=text mocha",
     "test:jest": "jest --testRegex test_ --env=node",
     "prettier:js": "prettier --write '**/*.js'",
     "prettier:other": "prettier --write '**/*.{json,md,yml}'",
-    "eslint": "eslint lib test --fix",
+    "eslint": "eslint src test --fix",
     "lint": "run-p lint:js lint:sass prettier:other",
     "lint:js": "run-s prettier:js eslint",
     "lint:sass": "stylelint '**/*.scss' --fix",
diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 0000000..379a324
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,23 @@
+// Tokens defining the True CSS output language.
+export const MODULE_TOKEN = '# Module: ';
+export const MODULE_NESTING_TOKEN = ' :: ';
+export const SUMMARY_TOKEN = '# SUMMARY ';
+export const END_SUMMARY_TOKEN = '----------';
+export const TEST_TOKEN = 'Test: ';
+export const PASS_TOKEN = '✔ ';
+export const FAIL_TOKEN = '✖ FAILED: [';
+export const END_FAIL_TOKEN = ']';
+export const ASSERT_TOKEN = 'ASSERT: ';
+export const FAILURE_DETAIL_TOKEN = '- ';
+export const FAILURE_TYPE_START_TOKEN = '[';
+export const FAILURE_TYPE_END_TOKEN = ']';
+export const OUTPUT_TOKEN = 'Output: ';
+export const EXPECTED_TOKEN = 'Expected: ';
+export const DETAILS_SEPARATOR_TOKEN = ': ';
+export const OUTPUT_START_TOKEN = 'OUTPUT';
+export const OUTPUT_END_TOKEN = 'END_OUTPUT';
+export const EXPECTED_START_TOKEN = 'EXPECTED';
+export const EXPECTED_END_TOKEN = 'END_EXPECTED';
+export const CONTAINED_START_TOKEN = 'CONTAINED';
+export const CONTAINED_END_TOKEN = 'END_CONTAINED';
+export const ASSERT_END_TOKEN = 'END_ASSERT';
diff --git a/lib/main.js b/src/index.ts
similarity index 76%
rename from lib/main.js
rename to src/index.ts
index 34a8cf8..e32871e 100644
--- a/lib/main.js
+++ b/src/index.ts
@@ -1,64 +1,84 @@
 /* eslint-disable no-plusplus, no-unused-vars, no-var, no-use-before-define */
 
-'use strict';
-
-const path = require('path');
-const assert = require('assert');
-
-const chalk = require('chalk');
-const css = require('css');
-const { find, forEach, last } = require('lodash');
-
-// Tokens defining the True CSS output language.
-const MODULE_TOKEN = '# Module: ';
-const MODULE_NESTING_TOKEN = ' :: ';
-const SUMMARY_TOKEN = '# SUMMARY ';
-const END_SUMMARY_TOKEN = '----------';
-const TEST_TOKEN = 'Test: ';
-const PASS_TOKEN = '✔ ';
-const FAIL_TOKEN = '✖ FAILED: [';
-const END_FAIL_TOKEN = ']';
-const ASSERT_TOKEN = 'ASSERT: ';
-const FAILURE_DETAIL_TOKEN = '- ';
-const FAILURE_TYPE_START_TOKEN = '[';
-const FAILURE_TYPE_END_TOKEN = ']';
-const OUTPUT_TOKEN = 'Output: ';
-const EXPECTED_TOKEN = 'Expected: ';
-const DETAILS_SEPARATOR_TOKEN = ': ';
-const OUTPUT_START_TOKEN = 'OUTPUT';
-const OUTPUT_END_TOKEN = 'END_OUTPUT';
-const EXPECTED_START_TOKEN = 'EXPECTED';
-const EXPECTED_END_TOKEN = 'END_EXPECTED';
-const CONTAINED_START_TOKEN = 'CONTAINED';
-const CONTAINED_END_TOKEN = 'END_CONTAINED';
-const ASSERT_END_TOKEN = 'END_ASSERT';
-
-var runSass = function (sassOptions, trueOptions) {
-  const sassOpts = Object.assign({}, sassOptions);
-  const trueOpts = Object.assign({}, trueOptions);
-  const sassPath = path.join(__dirname, '..', 'sass');
-  if (sassOpts.includePaths) {
-    sassOpts.includePaths.push(sassPath);
-  } else {
-    sassOpts.includePaths = [sassPath];
-  }
-  let sass;
-  if (trueOpts.sass) {
-    sass = trueOpts.sass;
-  } else {
-    // eslint-disable-next-line global-require
-    sass = require('sass');
-  }
-  // eslint-disable-next-line no-sync
-  const parsedCss = sass.renderSync(sassOpts).css.toString();
-  const modules = parse(parsedCss, trueOpts.contextLines);
-
-  forEach(modules, (module) => {
-    describeModule(module, trueOpts.describe, trueOpts.it);
-  });
+import * as path from 'path';
+import * as assert from 'assert';
+
+import type { Options } from 'sass';
+import * as css from 'css';
+import { find, forEach, last } from 'lodash';
+import { Comment, Node } from 'css';
+import * as chalk from 'chalk';
+
+import {
+  ASSERT_END_TOKEN,
+  ASSERT_TOKEN,
+  CONTAINED_END_TOKEN,
+  CONTAINED_START_TOKEN,
+  DETAILS_SEPARATOR_TOKEN,
+  END_FAIL_TOKEN,
+  END_SUMMARY_TOKEN,
+  EXPECTED_END_TOKEN,
+  EXPECTED_START_TOKEN,
+  EXPECTED_TOKEN,
+  FAIL_TOKEN,
+  FAILURE_DETAIL_TOKEN,
+  FAILURE_TYPE_END_TOKEN,
+  FAILURE_TYPE_START_TOKEN,
+  MODULE_NESTING_TOKEN,
+  MODULE_TOKEN,
+  OUTPUT_END_TOKEN,
+  OUTPUT_START_TOKEN,
+  OUTPUT_TOKEN,
+  PASS_TOKEN,
+  SUMMARY_TOKEN,
+  TEST_TOKEN,
+} from './constants';
+import {
+  cssStringToArrayOfRules,
+  falsyValues,
+  isCommentNode,
+  removeNewLines,
+  splitSelectorAndProperties,
+  startsWith,
+} from './utils';
+
+export interface TrueOptions {
+  sass?: typeof import('sass');
+  describe: (description: string, fn: () => void) => void;
+  it: (description: string, fn: () => void) => void;
+  contextLines?: number;
+}
+
+export interface Assertion {
+  description: string;
+  output?: string;
+  assertionType?: string;
+  expected?: string;
+  details?: string;
+  passed?: boolean;
+}
+
+export interface Test {
+  test: string;
+  assertions: Assertion[];
+}
+
+export interface Module {
+  module: string;
+  tests: Test[];
+  modules?: Module[];
+}
+
+export type Context = {
+  modules: Module[];
+  currentModule?: Module;
+  currentTest?: Test;
+  currentAssertion?: Assertion;
+  currentOutputRules?: Node[];
+  currentExpectedRules?: Node[];
 };
 
-var formatFailureMessage = function (assertion) {
+export function formatFailureMessage(assertion: Assertion) {
   let msg = assertion.description;
   msg = `${msg} ("${assertion.output}"`;
   msg = `${msg} ${assertion.assertionType} "${assertion.expected}"`;
@@ -66,13 +86,139 @@ var formatFailureMessage = function (assertion) {
     msg = `${msg} -- ${assertion.details}`;
   }
   msg = `${msg})`;
-  msg = `${msg}\n     ${chalk.green('+ expected ')}${chalk.red('- actual')}`;
-  msg = `${msg}\n\n     ${chalk.red(`-${assertion.output}`)}`;
-  msg = `${msg}\n     ${chalk.green(`+${assertion.expected}\n`)}`;
+  msg = `${msg}\n${chalk.green('+ expected ')}${chalk.red('- actual')}`;
+  msg = `${msg}\n\n${chalk.red(`-${assertion.output}`)}`;
+  msg = `${msg}\n${chalk.green(`+${assertion.expected}\n`)}`;
   return msg;
-};
+}
+
+function dealWithAnnoyingMediaQueries(rawCSS: string) {
+  const matchMediaQuery = /(@[a-zA-Z0-9:()\s-]+)/g;
+  // eslint-disable-next-line max-len
+  const matchCSSWithinMediaQueryBlock = /@[a-zA-Z0-9:()\s-]+{([a-zA-Z0-9:()\s-;._\\n{}]+)(?!}\\n})/g;
 
-var describeModule = function (module, describe, it) {
+  const mediaqueries = rawCSS.match(matchMediaQuery);
+  const rawCSSSansMediaQueries = rawCSS
+    .replace(matchMediaQuery, '')
+    .replace(matchCSSWithinMediaQueryBlock, '')
+    .replace(/^{/, '');
+  let matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
+  let i = 0;
+  let mediaQueryBasedSelectors = [];
+  const mediaqueryRule = /* istanbul ignore next */ (rule) =>
+    mediaqueries[i] + rule;
+  /* istanbul ignore next */
+  while (matches !== null) {
+    // This is necessary to avoid infinite loops with zero-width matches
+    if (matches.index === matchCSSWithinMediaQueryBlock.lastIndex) {
+      matchCSSWithinMediaQueryBlock.lastIndex++;
+    }
+
+    /* istanbul ignore next */
+    const cssWithinMediaQuery = removeNewLines(matches[1]);
+    const cssRules = cssStringToArrayOfRules(cssWithinMediaQuery);
+
+    mediaQueryBasedSelectors = mediaQueryBasedSelectors.concat(
+      cssRules.map(mediaqueryRule),
+    );
+
+    i++;
+    matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
+  }
+
+  return {
+    mediaQueryBasedSelectors,
+    rawCSSSansMediaQueries,
+  };
+}
+
+function createSelectorsRulesPairs(cssString: string) {
+  const processedMediaQueries = dealWithAnnoyingMediaQueries(cssString);
+  const mediaQueries = splitSelectorAndProperties(
+    processedMediaQueries.mediaQueryBasedSelectors,
+  );
+  const nonMediaQueries = processedMediaQueries.rawCSSSansMediaQueries;
+
+  const blocks = cssStringToArrayOfRules(nonMediaQueries);
+
+  const splitBlocks = splitSelectorAndProperties(blocks);
+
+  return splitBlocks.concat(mediaQueries).filter(falsyValues);
+}
+
+function contains(output, expected) {
+  const outputBlocks = createSelectorsRulesPairs(output);
+  const expectedBlocks = createSelectorsRulesPairs(expected);
+
+  const results = expectedBlocks.map((block) => {
+    const outputBlock = outputBlocks.find(
+      (element) => element.selector === block.selector,
+    );
+    if (outputBlock) {
+      // Turns a css string into an array of property-value pairs.
+      const expectedProperties = block.output
+        .split(';')
+        .map((propertyValuePair) => propertyValuePair.trim())
+        .filter((innerBlock) => innerBlock !== ' {' && innerBlock !== '}');
+
+      // This is the assertion itself!
+      return expectedProperties.every((property) =>
+        outputBlock.output.includes(property),
+      );
+    }
+    return false;
+  });
+
+  return results.every((result) => result === true);
+}
+
+function finishCurrentAssertion(ctx: Context) {
+  if (ctx.currentAssertion) {
+    ctx.currentTest.assertions.push(ctx.currentAssertion);
+    delete ctx.currentAssertion;
+  }
+}
+
+function finishCurrentTest(ctx: Context) {
+  finishCurrentAssertion(ctx);
+  if (ctx.currentTest) {
+    ctx.currentModule.tests.push(ctx.currentTest);
+    delete ctx.currentTest;
+  }
+}
+
+function insertModule(paths: string[], module: Module, ctx: Context) {
+  if (!ctx.modules) {
+    ctx.modules = [];
+  }
+
+  if (paths.length > 1) {
+    let newCtx = find(ctx.modules, { module: paths[0] });
+    if (!newCtx) {
+      newCtx = { module: paths[0] };
+      ctx.modules.push(newCtx);
+    }
+    insertModule(paths.slice(1), module, newCtx);
+  } else {
+    ctx.modules.push(module);
+  }
+}
+
+function finishCurrentModule(ctx: Context) {
+  finishCurrentTest(ctx);
+  if (ctx.currentModule) {
+    const paths = ctx.currentModule.module.split(MODULE_NESTING_TOKEN);
+    ctx.currentModule.module = last(paths);
+    insertModule(paths, ctx.currentModule, ctx);
+    delete ctx.currentModule;
+  }
+}
+
+function describeModule(
+  module: Module,
+  describe: TrueOptions['describe'],
+  it: TrueOptions['it'],
+) {
   describe(module.module, () => {
     forEach(module.modules, (submodule) => {
       describeModule(submodule, describe, it);
@@ -87,38 +233,43 @@ var describeModule = function (module, describe, it) {
       });
     });
   });
-};
+}
 
-var parse = function (rawCss, ctxLines) {
-  const contextLines = typeof ctxLines === 'undefined' ? 10 : ctxLines;
-  const lines = rawCss.split(/\r?\n/);
-
-  var parseCss = function () {
-    const ast = css.parse(rawCss);
-    const ctx = { modules: [] };
-    let handler = parseModule;
+export function runSass(sassOptions: Options, trueOptions: TrueOptions): void {
+  const sassOpts = Object.assign({}, sassOptions);
+  const trueOpts = Object.assign({}, trueOptions);
+  const sassPath = path.join(__dirname, '..', 'sass');
+  if (sassOpts.includePaths) {
+    sassOpts.includePaths.push(sassPath);
+  } else {
+    sassOpts.includePaths = [sassPath];
+  }
 
-    forEach(ast.stylesheet.rules, (rule) => {
-      handler = handler(rule, ctx);
-    });
+  let sass;
+  if (trueOpts.sass) {
+    sass = trueOpts.sass;
+  } else {
+    // eslint-disable-next-line global-require
+    sass = require('sass');
+  }
 
-    finishCurrentModule(ctx);
+  // eslint-disable-next-line no-sync
+  const parsedCss = sass.renderSync(sassOpts).css.toString();
+  const modules = parse(parsedCss, trueOpts.contextLines);
 
-    return ctx.modules;
-  };
+  forEach(modules, (module) => {
+    describeModule(module, trueOpts.describe, trueOpts.it);
+  });
+}
 
-  var parseError = function (msg, seeking, pos) {
-    const errorMsg =
-      `Line ${pos.start.line}, ` +
-      `column ${pos.start.column}: ${msg}; ` +
-      `looking for ${seeking}.\n` +
-      `-- Context --\n${lines
-        .slice(Math.max(0, pos.start.line - contextLines), pos.start.line)
-        .join('\n')}\n${' '.repeat(pos.start.column - 1)}^\n`;
-    return new Error(errorMsg);
-  };
+export function parse(
+  rawCss: Readonly<string>,
+  ctxLines?: Readonly<number>,
+): Module[] {
+  const contextLines = typeof ctxLines === 'undefined' ? 10 : ctxLines;
+  const lines = rawCss.split(/\r?\n/);
 
-  var parseModule = function (rule, ctx) {
+  function parseModule(rule: Comment, ctx: Context) {
     if (rule.type === 'comment') {
       const text = rule.comment.trim();
       if (!text) {
@@ -140,10 +291,35 @@ var parse = function (rawCss, ctxLines) {
     }
     // ignore other rule types
     return parseModule;
-  };
+  }
 
-  var ignoreUntilEndSummary = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  function parseCss() {
+    const ast = css.parse(rawCss);
+    const ctx: Context = { modules: [] };
+    let handler = parseModule;
+
+    forEach(ast.stylesheet.rules, (rule) => {
+      handler = handler(rule, ctx);
+    });
+
+    finishCurrentModule(ctx);
+
+    return ctx.modules;
+  }
+
+  function parseError(msg: string, seeking: string, pos: Node['position']) {
+    const errorMsg =
+      `Line ${pos.start.line}, ` +
+      `column ${pos.start.column}: ${msg}; ` +
+      `looking for ${seeking}.\n` +
+      `-- Context --\n${lines
+        .slice(Math.max(0, pos.start.line - contextLines), pos.start.line)
+        .join('\n')}\n${' '.repeat(pos.start.column - 1)}^\n`;
+    return new Error(errorMsg);
+  }
+
+  const ignoreUntilEndSummary = (rule: Node) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (startsWith(text, END_SUMMARY_TOKEN)) {
         return parseModule;
@@ -157,8 +333,8 @@ var parse = function (rawCss, ctxLines) {
     );
   };
 
-  var parseTest = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseTest = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (!text) {
         return parseTest;
@@ -180,9 +356,9 @@ var parse = function (rawCss, ctxLines) {
     return parseModule;
   };
 
-  var parseAssertion = function (rule, ctx) {
-    if (rule.type === 'comment') {
-      const text = rule.comment.trimLeft();
+  const parseAssertion = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
+      const text = rule.comment.trimStart();
       if (!text) {
         return parseAssertion;
       }
@@ -219,8 +395,8 @@ var parse = function (rawCss, ctxLines) {
     return parseModule;
   };
 
-  var parseFailureDetail = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseFailureDetail = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (startsWith(text, FAILURE_DETAIL_TOKEN)) {
         const detail = text.substring(FAILURE_DETAIL_TOKEN.length);
@@ -241,10 +417,9 @@ var parse = function (rawCss, ctxLines) {
         const splitAt = detail.indexOf(DETAILS_SEPARATOR_TOKEN);
         if (splitAt !== -1) {
           const key = detail.substring(0, splitAt);
-          const value = detail.substring(
+          ctx.currentAssertion[key.toLowerCase()] = detail.substring(
             splitAt + DETAILS_SEPARATOR_TOKEN.length,
           );
-          ctx.currentAssertion[key.toLowerCase()] = value;
           return parseFailureDetail;
         }
       }
@@ -257,8 +432,8 @@ var parse = function (rawCss, ctxLines) {
     );
   };
 
-  var parseAssertionOutputStart = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseAssertionOutputStart = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (!text) {
         return parseAssertionOutputStart;
@@ -276,8 +451,8 @@ var parse = function (rawCss, ctxLines) {
     );
   };
 
-  var parseAssertionOutput = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseAssertionOutput = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       if (rule.comment.trim() === OUTPUT_END_TOKEN) {
         ctx.currentAssertion.output = css.stringify({
           stylesheet: { rules: ctx.currentOutputRules },
@@ -290,8 +465,8 @@ var parse = function (rawCss, ctxLines) {
     return parseAssertionOutput;
   };
 
-  var parseAssertionExpectedStart = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseAssertionExpectedStart = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (!text) {
         return parseAssertionExpectedStart;
@@ -318,8 +493,8 @@ var parse = function (rawCss, ctxLines) {
     );
   };
 
-  var parseAssertionExpected = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseAssertionExpected = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       if (rule.comment.trim() === EXPECTED_END_TOKEN) {
         ctx.currentAssertion.expected = css.stringify({
           stylesheet: { rules: ctx.currentExpectedRules },
@@ -334,8 +509,8 @@ var parse = function (rawCss, ctxLines) {
     return parseAssertionExpected;
   };
 
-  var parseEndAssertion = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseEndAssertion = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       const text = rule.comment.trim();
       if (!text) {
         return parseEndAssertion;
@@ -357,8 +532,8 @@ var parse = function (rawCss, ctxLines) {
     );
   };
 
-  var parseAssertionContained = function (rule, ctx) {
-    if (rule.type === 'comment') {
+  const parseAssertionContained = (rule: Node, ctx: Context) => {
+    if (isCommentNode(rule)) {
       if (rule.comment.trim() === CONTAINED_END_TOKEN) {
         ctx.currentAssertion.expected = css.stringify({
           stylesheet: { rules: ctx.currentExpectedRules },
@@ -376,160 +551,4 @@ var parse = function (rawCss, ctxLines) {
   };
 
   return parseCss();
-};
-
-var falsyValues = function (item) {
-  return Boolean(item);
-};
-
-var contains = function (output, expected) {
-  const outputBlocks = createSelectorsRulesPairs(output);
-  const expectedBlocks = createSelectorsRulesPairs(expected);
-
-  const results = expectedBlocks.map((block) => {
-    const outputBlock = outputBlocks.find(
-      (element) => element.selector === block.selector,
-    );
-    if (outputBlock) {
-      // Turns a css string into an array of property-value pairs.
-      const expectedProperties = block.output
-        .split(';')
-        .map((propertyValuePair) => propertyValuePair.trim())
-        .filter((innerBlock) => innerBlock !== ' {' && innerBlock !== '}');
-
-      // This is the assertion itself!
-      return expectedProperties.every((property) =>
-        outputBlock.output.includes(property),
-      );
-    }
-    return false;
-  });
-
-  return results.every((result) => result === true);
-};
-
-var createSelectorsRulesPairs = function (cssString) {
-  const processedMediaQueries = dealWithAnnoyingMediaQueries(cssString);
-  const mediaQueries = splitSelectorAndProperties(
-    processedMediaQueries.mediaQueryBasedSelectors,
-  );
-  const nonMediaQueries = processedMediaQueries.rawCSSSansMediaQueries;
-
-  const blocks = cssStringToArrayOfRules(nonMediaQueries);
-
-  const splitBlocks = splitSelectorAndProperties(blocks);
-
-  return splitBlocks.concat(mediaQueries).filter(falsyValues);
-};
-
-var splitSelectorAndProperties = function (blocks) {
-  return blocks.map((block) => {
-    const temp = block.split('{');
-    const selector = temp[0];
-    const output = temp[1];
-    const splitBlock = { selector, output };
-    return splitBlock;
-  });
-};
-
-var removeNewLines = function (cssString) {
-  return cssString.replace(/\n/g, '');
-};
-
-var cssStringToArrayOfRules = function (cssString) {
-  return removeNewLines(cssString)
-    .split(/\s*}(?![\s]*["',}])/g)
-    .filter(falsyValues);
-};
-
-var dealWithAnnoyingMediaQueries = function (rawCSS) {
-  const matchMediaQuery = /(@[a-zA-Z0-9:()\s-]+)/g;
-  // eslint-disable-next-line max-len
-  const matchCSSWithinMediaQueryBlock = /@[a-zA-Z0-9:()\s-]+{([a-zA-Z0-9:()\s-;._\\n{}]+)(?!}\\n})/g;
-
-  const mediaqueries = rawCSS.match(matchMediaQuery);
-  const rawCSSSansMediaQueries = rawCSS
-    .replace(matchMediaQuery, '')
-    .replace(matchCSSWithinMediaQueryBlock, '')
-    .replace(/^{/, '');
-  let matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
-  let i = 0;
-  let mediaQueryBasedSelectors = [];
-  const mediaqueryRule = /* istanbul ignore next */ (rule) =>
-    mediaqueries[i] + rule;
-  /* istanbul ignore next */
-  while (matches !== null) {
-    // This is necessary to avoid infinite loops with zero-width matches
-    if (matches.index === matchCSSWithinMediaQueryBlock.lastIndex) {
-      matchCSSWithinMediaQueryBlock.lastIndex++;
-    }
-
-    /* istanbul ignore next */
-    const cssWithinMediaQuery = removeNewLines(matches[1]);
-    const cssRules = cssStringToArrayOfRules(cssWithinMediaQuery);
-
-    mediaQueryBasedSelectors = mediaQueryBasedSelectors.concat(
-      cssRules.map(mediaqueryRule),
-    );
-
-    i++;
-    matches = matchCSSWithinMediaQueryBlock.exec(rawCSS);
-  }
-
-  return {
-    mediaQueryBasedSelectors,
-    rawCSSSansMediaQueries,
-  };
-};
-
-var finishCurrentModule = function (ctx) {
-  finishCurrentTest(ctx);
-  if (ctx.currentModule) {
-    const paths = ctx.currentModule.module.split(MODULE_NESTING_TOKEN);
-    ctx.currentModule.module = last(paths);
-    insertModule(paths, ctx.currentModule, ctx);
-    delete ctx.currentModule;
-  }
-};
-
-var finishCurrentTest = function (ctx) {
-  finishCurrentAssertion(ctx);
-  if (ctx.currentTest) {
-    ctx.currentModule.tests.push(ctx.currentTest);
-    delete ctx.currentTest;
-  }
-};
-
-var finishCurrentAssertion = function (ctx) {
-  if (ctx.currentAssertion) {
-    ctx.currentTest.assertions.push(ctx.currentAssertion);
-    delete ctx.currentAssertion;
-  }
-};
-
-var insertModule = function (paths, module, ctx) {
-  if (!ctx.modules) {
-    ctx.modules = [];
-  }
-
-  if (paths.length > 1) {
-    let newCtx = find(ctx.modules, { module: paths[0] });
-    if (!newCtx) {
-      newCtx = { module: paths[0] };
-      ctx.modules.push(newCtx);
-    }
-    insertModule(paths.slice(1), module, newCtx);
-  } else {
-    ctx.modules.push(module);
-  }
-};
-
-var startsWith = function (text, token) {
-  return text.substring(0, token.length) === token;
-};
-
-module.exports = {
-  runSass,
-  formatFailureMessage,
-  parse,
-};
+}
diff --git a/src/utils.ts b/src/utils.ts
new file mode 100644
index 0000000..d8b6371
--- /dev/null
+++ b/src/utils.ts
@@ -0,0 +1,32 @@
+import { Comment, Node } from 'css';
+
+export function falsyValues(item?: any) {
+  return Boolean(item);
+}
+
+export function isCommentNode(node: Node): node is Comment {
+  return node.type === 'comment';
+}
+
+export function startsWith(text: string, token: string) {
+  return text.indexOf(token) === 0;
+}
+
+export function removeNewLines(cssString: string) {
+  return cssString.replace(/\n/g, '');
+}
+
+export function cssStringToArrayOfRules(cssString: string) {
+  return removeNewLines(cssString)
+    .split(/\s*}(?![\s]*["',}])/g)
+    .filter(falsyValues);
+}
+
+export function splitSelectorAndProperties(blocks: string[]) {
+  return blocks.map((block) => {
+    const temp = block.split('{');
+    const selector = temp[0];
+    const output = temp[1];
+    return { selector, output };
+  });
+}
diff --git a/test/test_main.js b/test/test_main.js
index 0daa106..1dabd95 100644
--- a/test/test_main.js
+++ b/test/test_main.js
@@ -1,7 +1,5 @@
 /* eslint-env mocha, jest */
 
-'use strict';
-
 const path = require('path');
 
 const chalk = require('chalk');
diff --git a/test/test_sass.js b/test/test_sass.js
index bfb17a1..e1faa58 100644
--- a/test/test_sass.js
+++ b/test/test_sass.js
@@ -1,7 +1,5 @@
 /* eslint-env mocha, jest */
 
-'use strict';
-
 const path = require('path');
 
 const main = require('../lib/main.js');
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..92d9aef
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "target": "es5",
+    "sourceMap": true,
+    "outDir": "lib",
+    "declaration": true
+  },
+  "exclude": ["node_modules", "lib"]
+}
diff --git a/yarn.lock b/yarn.lock
index 258a90f..f0b331f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -554,11 +554,23 @@
   dependencies:
     "@babel/types" "^7.3.0"
 
+"@types/chalk@^2.2.0":
+  version "2.2.0"
+  resolved "https://registry.yarnpkg.com/@types/chalk/-/chalk-2.2.0.tgz#b7f6e446f4511029ee8e3f43075fb5b73fbaa0ba"
+  integrity sha512-1zzPV9FDe1I/WHhRkf9SNgqtRJWZqrBWgu7JGveuHmmyR9CnAPCie2N/x+iHrgnpYBIcCJWHBoMRv2TRWktsvw==
+  dependencies:
+    chalk "*"
+
 "@types/color-name@^1.1.1":
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/@types/color-name/-/color-name-1.1.1.tgz#1c1261bbeaa10a8055bbc5d8ab84b7b2afc846a0"
   integrity sha512-rr+OQyAjxze7GgWrSaJwydHStIhHq2lvY3BOC2Mj7KnzI7XK0Uw1TOOdI9lDoajEbSWLiYgoo4f1R51erQfhPQ==
 
+"@types/css@0.0.33":
+  version "0.0.33"
+  resolved "https://registry.yarnpkg.com/@types/css/-/css-0.0.33.tgz#d0b49c4090c09c8e5dc01364560627e5ebb770f2"
+  integrity sha512-qjeDgh86R0LIeEM588q65yatc8Yyo/VvSIYFqq8JOIHDolhGNX0rz7k/OuxqDpnpqlefoHj8X4Ai/6hT9IWtKQ==
+
 "@types/graceful-fs@^4.1.2":
   version "4.1.3"
   resolved "https://registry.yarnpkg.com/@types/graceful-fs/-/graceful-fs-4.1.3.tgz#039af35fe26bec35003e8d86d2ee9c586354348f"
@@ -586,6 +598,11 @@
     "@types/istanbul-lib-coverage" "*"
     "@types/istanbul-lib-report" "*"
 
+"@types/json-schema@^7.0.7":
+  version "7.0.9"
+  resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.9.tgz#97edc9037ea0c38585320b28964dde3b39e4660d"
+  integrity sha512-qcUXuemtEu+E5wZSJHNxUXeCZhAfXKQ41D+duX+VYPde7xyEVZci+/oXKJL13tnRs9lR2pr4fod59GT6/X1/yQ==
+
 "@types/json5@^0.0.29":
   version "0.0.29"
   resolved "https://registry.yarnpkg.com/@types/json5/-/json5-0.0.29.tgz#ee28707ae94e11d2b827bcbe5270bcea7f3e71ee"
@@ -601,6 +618,11 @@
   resolved "https://registry.yarnpkg.com/@types/node/-/node-14.0.24.tgz#b0f86f58564fa02a28b68f8b55d4cdec42e3b9d6"
   integrity sha512-btt/oNOiDWcSuI721MdL8VQGnjsKjlTMdrKyTcLCKeQp/n4AAMFJ961wMbp+09y8WuGPClDEv07RIItdXKIXAA==
 
+"@types/node@^16.11.11":
+  version "16.11.11"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-16.11.11.tgz#6ea7342dfb379ea1210835bada87b3c512120234"
+  integrity sha512-KB0sixD67CeecHC33MYn+eYARkqTheIRNuu97y2XMjR7Wu3XibO1vaY6VBV6O/a89SPI81cEUIYT87UqUWlZNw==
+
 "@types/normalize-package-data@^2.4.0":
   version "2.4.0"
   resolved "https://registry.yarnpkg.com/@types/normalize-package-data/-/normalize-package-data-2.4.0.tgz#e486d0d97396d79beedd0a6e33f4534ff6b4973e"
@@ -621,6 +643,13 @@
   resolved "https://registry.yarnpkg.com/@types/q/-/q-1.5.4.tgz#15925414e0ad2cd765bfef58842f7e26a7accb24"
   integrity sha512-1HcDas8SEj4z1Wc696tH56G8OlRaH/sqZOynNNB+HF0WOeXPaxTtbYzJY2oEfiUxjSKjhCKr+MvR7dCHcEelug==
 
+"@types/sass@^1.43.1":
+  version "1.43.1"
+  resolved "https://registry.yarnpkg.com/@types/sass/-/sass-1.43.1.tgz#86bb0168e9e881d7dade6eba16c9ed6d25dc2f68"
+  integrity sha512-BPdoIt1lfJ6B7rw35ncdwBZrAssjcwzI5LByIrYs+tpXlj/CAkuVdRsgZDdP4lq5EjyWzwxZCqAoFyHKFwp32g==
+  dependencies:
+    "@types/node" "*"
+
 "@types/stack-utils@^1.0.1":
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-1.0.1.tgz#0a851d3bd96498fa25c33ab7278ed3bd65f06c3e"
@@ -643,6 +672,76 @@
   dependencies:
     "@types/yargs-parser" "*"
 
+"@typescript-eslint/eslint-plugin@^4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/eslint-plugin/-/eslint-plugin-4.33.0.tgz#c24dc7c8069c7706bc40d99f6fa87edcb2005276"
+  integrity sha512-aINiAxGVdOl1eJyVjaWn/YcVAq4Gi/Yo35qHGCnqbWVz61g39D0h23veY/MA0rFFGfxK7TySg2uwDeNv+JgVpg==
+  dependencies:
+    "@typescript-eslint/experimental-utils" "4.33.0"
+    "@typescript-eslint/scope-manager" "4.33.0"
+    debug "^4.3.1"
+    functional-red-black-tree "^1.0.1"
+    ignore "^5.1.8"
+    regexpp "^3.1.0"
+    semver "^7.3.5"
+    tsutils "^3.21.0"
+
+"@typescript-eslint/experimental-utils@4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/experimental-utils/-/experimental-utils-4.33.0.tgz#6f2a786a4209fa2222989e9380b5331b2810f7fd"
+  integrity sha512-zeQjOoES5JFjTnAhI5QY7ZviczMzDptls15GFsI6jyUOq0kOf9+WonkhtlIhh0RgHRnqj5gdNxW5j1EvAyYg6Q==
+  dependencies:
+    "@types/json-schema" "^7.0.7"
+    "@typescript-eslint/scope-manager" "4.33.0"
+    "@typescript-eslint/types" "4.33.0"
+    "@typescript-eslint/typescript-estree" "4.33.0"
+    eslint-scope "^5.1.1"
+    eslint-utils "^3.0.0"
+
+"@typescript-eslint/parser@^4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/parser/-/parser-4.33.0.tgz#dfe797570d9694e560528d18eecad86c8c744899"
+  integrity sha512-ZohdsbXadjGBSK0/r+d87X0SBmKzOq4/S5nzK6SBgJspFo9/CUDJ7hjayuze+JK7CZQLDMroqytp7pOcFKTxZA==
+  dependencies:
+    "@typescript-eslint/scope-manager" "4.33.0"
+    "@typescript-eslint/types" "4.33.0"
+    "@typescript-eslint/typescript-estree" "4.33.0"
+    debug "^4.3.1"
+
+"@typescript-eslint/scope-manager@4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/scope-manager/-/scope-manager-4.33.0.tgz#d38e49280d983e8772e29121cf8c6e9221f280a3"
+  integrity sha512-5IfJHpgTsTZuONKbODctL4kKuQje/bzBRkwHE8UOZ4f89Zeddg+EGZs8PD8NcN4LdM3ygHWYB3ukPAYjvl/qbQ==
+  dependencies:
+    "@typescript-eslint/types" "4.33.0"
+    "@typescript-eslint/visitor-keys" "4.33.0"
+
+"@typescript-eslint/types@4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/types/-/types-4.33.0.tgz#a1e59036a3b53ae8430ceebf2a919dc7f9af6d72"
+  integrity sha512-zKp7CjQzLQImXEpLt2BUw1tvOMPfNoTAfb8l51evhYbOEEzdWyQNmHWWGPR6hwKJDAi+1VXSBmnhL9kyVTTOuQ==
+
+"@typescript-eslint/typescript-estree@4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/typescript-estree/-/typescript-estree-4.33.0.tgz#0dfb51c2908f68c5c08d82aefeaf166a17c24609"
+  integrity sha512-rkWRY1MPFzjwnEVHsxGemDzqqddw2QbTJlICPD9p9I9LfsO8fdmfQPOX3uKfUaGRDFJbfrtm/sXhVXN4E+bzCA==
+  dependencies:
+    "@typescript-eslint/types" "4.33.0"
+    "@typescript-eslint/visitor-keys" "4.33.0"
+    debug "^4.3.1"
+    globby "^11.0.3"
+    is-glob "^4.0.1"
+    semver "^7.3.5"
+    tsutils "^3.21.0"
+
+"@typescript-eslint/visitor-keys@4.33.0":
+  version "4.33.0"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/visitor-keys/-/visitor-keys-4.33.0.tgz#2a22f77a41604289b7a186586e9ec48ca92ef1dd"
+  integrity sha512-uqi/2aSz9g2ftcHWf8uLPJA70rUv6yuMW5Bohw+bwcuzaxQIHaKFZCKGoGXIrc9vkTJ3+0txM73K0Hq3d5wgIg==
+  dependencies:
+    "@typescript-eslint/types" "4.33.0"
+    eslint-visitor-keys "^2.0.0"
+
 a-sync-waterfall@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/a-sync-waterfall/-/a-sync-waterfall-1.0.1.tgz#75b6b6aa72598b497a125e7a2770f14f4c8a1fa7"
@@ -1472,6 +1571,11 @@ chai@^4.1.2:
     pathval "^1.1.0"
     type-detect "^4.0.5"
 
+chalk@*:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/chalk/-/chalk-5.0.0.tgz#bd96c6bb8e02b96e08c0c3ee2a9d90e050c7b832"
+  integrity sha512-/duVOqst+luxCQRKEo4bNxinsOQtMP80ZYm7mMqzuh5PociNL0PvmHFvREJ9ueYL2TxlHjBcmLCdmocx9Vg+IQ==
+
 chalk@^1.0.0:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/chalk/-/chalk-1.1.3.tgz#a8115c55e4a702fe4d150abd3872822a7e09fc98"
@@ -2111,6 +2215,13 @@ debug@^4.0.1, debug@^4.1.0, debug@^4.1.1:
   dependencies:
     ms "^2.1.1"
 
+debug@^4.3.1:
+  version "4.3.3"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-4.3.3.tgz#04266e0b70a98d4462e6e288e38259213332b664"
+  integrity sha512-/zxw5+vh1Tfv+4Qn7a5nsbcJKPaSvCDhojn6FEl9vupwK2VCSDtEiEtqr8DFtzYFOdz63LBkxec7DYuc2jon6Q==
+  dependencies:
+    ms "2.1.2"
+
 decamelize-keys@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/decamelize-keys/-/decamelize-keys-1.1.0.tgz#d171a87933252807eb3cb61dc1c1445d078df2d9"
@@ -2634,6 +2745,14 @@ eslint-scope@^5.1.0:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
+eslint-scope@^5.1.1:
+  version "5.1.1"
+  resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-5.1.1.tgz#e786e59a66cb92b3f6c1fb0d508aab174848f48c"
+  integrity sha512-2NxwbF/hZ0KpepYN0cNbo+FN6XoK7GaHlQhgx/hIZl6Va0bF45RQOOwhLIy8lQDbuCiadSLCBnH2CFYquit5bw==
+  dependencies:
+    esrecurse "^4.3.0"
+    estraverse "^4.1.1"
+
 eslint-utils@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-2.1.0.tgz#d2de5e03424e707dc10c74068ddedae708741b27"
@@ -2641,11 +2760,23 @@ eslint-utils@^2.1.0:
   dependencies:
     eslint-visitor-keys "^1.1.0"
 
+eslint-utils@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-3.0.0.tgz#8aebaface7345bb33559db0a1f13a1d2d48c3672"
+  integrity sha512-uuQC43IGctw68pJA1RgbQS8/NP7rch6Cwd4j3ZBtgo4/8Flj4eGE7ZYSZRN3iq5pVUv6GPdW5Z1RFleo84uLDA==
+  dependencies:
+    eslint-visitor-keys "^2.0.0"
+
 eslint-visitor-keys@^1.1.0, eslint-visitor-keys@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.3.0.tgz#30ebd1ef7c2fdff01c3a4f151044af25fab0523e"
   integrity sha512-6J72N8UNa462wa/KFODt/PJ3IU60SDpC3QXC1Hjc1BXXpfL2C9R5+AU7jhe0F6GREqVMh4Juu+NY7xn+6dipUQ==
 
+eslint-visitor-keys@^2.0.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-2.1.0.tgz#f65328259305927392c938ed44eb0a5c9b2bd303"
+  integrity sha512-0rSmRBzXgDzIsD6mGdJgevzgezI534Cer5L/vyMX0kHzT/jiB43jRhd9YUlMGYLQy2zprNmoT8qasCGtY+QaKw==
+
 eslint@^7.5.0:
   version "7.5.0"
   resolved "https://registry.yarnpkg.com/eslint/-/eslint-7.5.0.tgz#9ecbfad62216d223b82ac9ffea7ef3444671d135"
@@ -2716,6 +2847,13 @@ esrecurse@^4.1.0:
   dependencies:
     estraverse "^4.1.0"
 
+esrecurse@^4.3.0:
+  version "4.3.0"
+  resolved "https://registry.yarnpkg.com/esrecurse/-/esrecurse-4.3.0.tgz#7ad7964d679abb28bee72cec63758b1c5d2c9921"
+  integrity sha512-KmfKL3b6G+RXvP8N1vr3Tq1kL/oCFgn2NYXEtqP8/L3pKapUA4G8cFVaoF3SU323CD4XypR/ffioHmkti6/Tag==
+  dependencies:
+    estraverse "^5.2.0"
+
 estraverse@^4.1.0, estraverse@^4.1.1, estraverse@^4.2.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-4.3.0.tgz#398ad3f3c5a24948be7725e83d11a7de28cdbd1d"
@@ -2726,6 +2864,11 @@ estraverse@^5.1.0:
   resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-5.1.0.tgz#374309d39fd935ae500e7b92e8a6b4c720e59642"
   integrity sha512-FyohXK+R0vE+y1nHLoBM7ZTyqRpqAlhdZHCWIWEviFLiGB8b04H6bQs8G+XTthacvT8VuwvteiP7RJSxMs8UEw==
 
+estraverse@^5.2.0:
+  version "5.3.0"
+  resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-5.3.0.tgz#2eea5290702f26ab8fe5370370ff86c965d21123"
+  integrity sha512-MMdARuVEQziNTeJD8DgMqmhwR11BRQ/cBP+pLtYdSTnf3MIO8fFeiINEbX36ZdNlfU/7A9f3gUw49B3oQsvwBA==
+
 esutils@^2.0.2:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/esutils/-/esutils-2.0.3.tgz#74d2eb4de0b8da1293711910d50775b9b710ef64"
@@ -3480,6 +3623,18 @@ globby@^11.0.1:
     merge2 "^1.3.0"
     slash "^3.0.0"
 
+globby@^11.0.3:
+  version "11.0.4"
+  resolved "https://registry.yarnpkg.com/globby/-/globby-11.0.4.tgz#2cbaff77c2f2a62e71e9b2813a67b97a3a3001a5"
+  integrity sha512-9O4MVG9ioZJ08ffbcyVYyLOJLk5JQ688pJ4eMGLpdWLHq/Wr1D9BlriLQyL0E+jbkuePVZXYFj47QM/v093wHg==
+  dependencies:
+    array-union "^2.1.0"
+    dir-glob "^3.0.1"
+    fast-glob "^3.1.1"
+    ignore "^5.1.4"
+    merge2 "^1.3.0"
+    slash "^3.0.0"
+
 globby@^8.0.1:
   version "8.0.2"
   resolved "https://registry.yarnpkg.com/globby/-/globby-8.0.2.tgz#5697619ccd95c5275dbb2d6faa42087c1a941d8d"
@@ -5447,6 +5602,13 @@ lru-cache@^4.0.1:
     pseudomap "^1.0.2"
     yallist "^2.1.2"
 
+lru-cache@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/lru-cache/-/lru-cache-6.0.0.tgz#6d6fe6570ebd96aaf90fcad1dafa3b2566db3a94"
+  integrity sha512-Jo6dJ04CmSjuznwJSS3pUeWmd/H0ffTlkXXgwZi+eq1UCmqQwCh+eLsYOYCwY991i2Fah4h1BEMCx4qThGbsiA==
+  dependencies:
+    yallist "^4.0.0"
+
 lunr@^2.3.8:
   version "2.3.8"
   resolved "https://registry.yarnpkg.com/lunr/-/lunr-2.3.8.tgz#a8b89c31f30b5a044b97d2d28e2da191b6ba2072"
@@ -7460,6 +7622,13 @@ semver@^7.2.1, semver@^7.3.2:
   resolved "https://registry.yarnpkg.com/semver/-/semver-7.3.2.tgz#604962b052b81ed0786aae84389ffba70ffd3938"
   integrity sha512-OrOb32TeeambH6UrhtShmF7CRDqhL6/5XpPNp2DuRH6+9QLw/orhp72j87v8Qa1ScDkvrrBNpZcDejAirJmfXQ==
 
+semver@^7.3.5:
+  version "7.3.5"
+  resolved "https://registry.yarnpkg.com/semver/-/semver-7.3.5.tgz#0b621c879348d8998e4b0e4be94b3f12e6018ef7"
+  integrity sha512-PoeGJYh8HK4BTO/a9Tf6ZG3veo/A7ZVsYrSA6J8ny9nb3B1VrpkuN+z9OE5wfE5p6H4LchYZsegiQgbJD94ZFQ==
+  dependencies:
+    lru-cache "^6.0.0"
+
 serialize-javascript@3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/serialize-javascript/-/serialize-javascript-3.0.0.tgz#492e489a2d77b7b804ad391a5f5d97870952548e"
@@ -8379,6 +8548,18 @@ tsconfig-paths@^3.9.0:
     minimist "^1.2.0"
     strip-bom "^3.0.0"
 
+tslib@^1.8.1:
+  version "1.14.1"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.14.1.tgz#cf2d38bdc34a134bcaf1091c41f6619e2f672d00"
+  integrity sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==
+
+tsutils@^3.21.0:
+  version "3.21.0"
+  resolved "https://registry.yarnpkg.com/tsutils/-/tsutils-3.21.0.tgz#b48717d394cea6c1e096983eed58e9d61715b623"
+  integrity sha512-mHKK3iUXL+3UF6xL5k0PEhKRUBKPBCv/+RkEOpjRWxxx27KKRBmmA60A9pgOUvMi8GKhRMPEmjBRPzs2W7O1OA==
+  dependencies:
+    tslib "^1.8.1"
+
 tunnel-agent@^0.6.0:
   version "0.6.0"
   resolved "https://registry.yarnpkg.com/tunnel-agent/-/tunnel-agent-0.6.0.tgz#27a5dea06b36b04a0a9966774b290868f0fc40fd"
@@ -8442,6 +8623,11 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=
 
+typescript@^4.4.4:
+  version "4.5.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.2.tgz#8ac1fba9f52256fdb06fb89e4122fa6a346c2998"
+  integrity sha512-5BlMof9H1yGt0P8/WF+wPNw6GfctgGjXp5hkblpyT+8rkASSmkUKMXrxR0Xg8ThVCi/JnHQiKXeBaEwCeQwMFw==
+
 typogr@^0.6.8:
   version "0.6.8"
   resolved "https://registry.yarnpkg.com/typogr/-/typogr-0.6.8.tgz#73490c0ddda2cbd20f88c10f7a6974deab455bb4"
@@ -9015,6 +9201,11 @@ yallist@^2.1.2:
   resolved "https://registry.yarnpkg.com/yallist/-/yallist-2.1.2.tgz#1c11f9218f076089a47dd512f93c6699a6a81d52"
   integrity sha1-HBH5IY8HYImkfdUS+TxmmaaoHVI=
 
+yallist@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/yallist/-/yallist-4.0.0.tgz#9bb92790d9c0effec63be73519e11a35019a3a72"
+  integrity sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A==
+
 yaml@^1.7.2:
   version "1.10.0"
   resolved "https://registry.yarnpkg.com/yaml/-/yaml-1.10.0.tgz#3b593add944876077d4d683fee01081bd9fff31e"