Add example testing directly to Turf core testing

.eslintignore

@@ -8,3 +8,4 @@ marchingsquares-isobands.js
 rollup.config.js
 simplepolygon.js
 types.js
+test.example.js

packages/turf/.gitignore

@@ -1,2 +1,3 @@
 turf.js
 turf.min.js
+test.example.js

packages/turf/package.json

@@ -14,6 +14,7 @@
   ],
   "scripts": {
     "test": "node test.js",
+    "posttest": "echo \"manually execute => node test.example.js\"",
     "prepublish": "npm run build",
     "build": "browserify index.js -s turf > turf.js && uglifyjs turf.js -c -m > turf.min.js",
     "size": "browserify index.js --full-paths -s turf | uglifyjs -c -m | discify | hcat"
@@ -141,6 +142,8 @@
   "devDependencies": {
     "browserify": "~9.0.3",
     "disc": "^1.3.2",
+    "documentation": "^4.0.0-rc.1",
+    "glob": "^7.1.2",
     "hcat": "0.0.5",
     "jsdoc": "^3.3.0-beta1",
     "tape": "^4.7.0",

packages/turf/test.js

@@ -1,6 +1,8 @@
 const fs = require('fs');
 const path = require('path');
+const glob = require('glob');
 const test = require('tape');
+const documentation = require('documentation');
 
 // Helpers
 const directory = path.join(__dirname, '..');
@@ -127,3 +129,73 @@ test('turf - parsing dependencies from index.js', t => {
     }
     t.end();
 });
+
+/**
+ * =========================
+ * Builds => test.example.js
+ * =========================
+ *
+ * To-Do
+ * -----
+ * - [ ] Fix @example errors
+ * - [ ] Add 'node test.example' in package.json => scripts => posttest
+ * - [ ] Include `addToMap` validation tests
+ */
+
+// File Paths
+const testFilePath = path.join(__dirname, 'test.example.js');
+const turfModulesPath = path.join(__dirname, '..', 'turf-*', 'index.js');
+
+// Test Strings
+const requireString = `const test = require('tape');
+const turf = require('./');
+`;
+
+/**
+ * Generate Test String
+ *
+ * @param {Object} turfFunction Documentation function object
+ * @param {Object} example Documentation example object
+ * @returns {string} Test String
+ */
+function testString(turfFunction, example) {
+    const turfName = turfFunction.name;
+    const testFunctionName = turfName + 'Test';
+    return `
+test('turf-${turfName}', t => {
+    const ${testFunctionName} = () => {
+        ${example.description}
+    }
+    ${testFunctionName}();
+    t.pass('${turfName}');
+    t.end();
+});
+`;
+}
+
+// Iterate over each module and retrieve @example to build tests from them
+glob(turfModulesPath, (err, files) => {
+    if (err) throw err;
+
+    // Read each JSDocs from index.js files
+    documentation.build(files, {}).then(turfFunctions => {
+        if (err) throw err;
+
+        // Write header of test.js
+        const writeableStream = fs.createWriteStream(testFilePath);
+        writeableStream.write(requireString);
+        writeableStream.on('error', err => { throw err; });
+
+        // Retrieve @example
+        turfFunctions.forEach(turfFunction => {
+            if (turfFunction.examples) {
+
+                // Save to test.js
+                turfFunction.examples.forEach(example => {
+                    writeableStream.write(testString(turfFunction, example));
+                });
+            }
+        });
+        writeableStream.end();
+    });
+});