add toRender matcher

test/helpers/helpers.js

@@ -1,5 +1,42 @@
-var marked = require('../../lib/marked.js');
+const marked = require('../../');
+const HtmlDiffer = require('@markedjs/html-differ').HtmlDiffer;
+const htmlDiffer = new HtmlDiffer({ignoreSelfClosingSlash: true});
 
 beforeEach(function () {
   marked.setOptions(marked.getDefaults());
+
+  jasmine.addMatchers({
+    toRender: function () {
+      return {
+        compare: function (spec, expected) {
+          const result = {};
+          const actual = marked(spec.markdown, spec.options);
+          result.pass = htmlDiffer.isEqual(expected, actual);
+
+          if (result.pass) {
+            result.message = spec.markdown + '\n------\n\nExpected: Should Fail';
+          } else {
+            var expectedHtml = expected.replace(/\s/g, '');
+            var actualHtml = actual.replace(/\s/g, '');
+
+            for (var i = 0; i < expectedHtml.length; i++) {
+              if (actualHtml[i] !== expectedHtml[i]) {
+                actualHtml = actualHtml.substring(
+                  Math.max(i - 30, 0),
+                  Math.min(i + 30, actualHtml.length));
+
+                expectedHtml = expectedHtml.substring(
+                  Math.max(i - 30, 0),
+                  Math.min(i + 30, expectedHtml.length));
+
+                break;
+              }
+            }
+            result.message = 'Expected:\n' + expectedHtml + '\n\nActual:\n' + actualHtml;
+          }
+          return result;
+        }
+      };
+    }
+  });
 });