feat(tests): add initial testing

Author: addyosmani

package.json

@@ -10,10 +10,10 @@
   "jsnext:main": "dist/quicklink.mjs",
   "umd:main": "dist/quicklink.umd.js",
   "scripts": {
-    "lint": "eslint src/*.mjs",
+    "test": "eslint src/*.mjs && jest",
     "build": "microbundle src/index.mjs --no-sourcemap",
     "prepare": "npm run -s build",
-    "release": "cross-var npm run build -s && cross-var git commit -am $npm_package_version && cross-var git tag $npm_package_version && git push && git push --tags && npm publish"
+    "release": "cross-var npm run build -s && cross-var git commit -am $npm_package_version && cross-var git tag $npm_package_version && git push && git push --tags && npm publish --access public"
   },
   "keywords": [
     "prefetch",
@@ -23,10 +23,25 @@
     "background",
     "speed"
   ],
+  "jest": {
+    "testURL": "http://localhost/",
+    "testMatch": [
+      "<rootDir>/test/**/*.?(m)js?(x)"
+    ],
+    "moduleFileExtensions": [
+      "mjs",
+      "js"
+    ],
+    "transform": {
+      "^.+\\.m?jsx?$": "babel-jest"
+    }
+  },
   "devDependencies": {
+    "babel-preset-env": "^1.7.0",
     "cross-var": "^1.1.0",
     "eslint": "^5.9.0",
     "eslint-config-google": "^0.11.0",
+    "jest": "^23.6.0",
     "microbundle": "^0.7.0"
   },
   "dependencies": {}

src/index.mjs

@@ -66,19 +66,24 @@ const prefetchURLs = function (urls, priority) {
  * @param {Array} options.urls - Array of URLs to prefetch (override)
  * @param {Object} options.el - DOM element to prefetch in-viewport links of
  * @param {string} options.priority - Attempt to fetch with higher priority (low or high)
+ * @return {Object} Promise
  */
 export default function (options) {
-  options = options || {priority: 'low'};
-  requestIdleCallback(() => {
-    // Prefetch an array of URLs if supplied (as an override)
-    if (options.urls !== undefined && options.urls.length > 0) {
-      prefetchURLs(options.urls, options.priority);
-    } else {
-      // Element to extract in-viewport links for
-      const el = options.el || document;
-      extractInViewportLinks(el).then(urls => {
-        prefetchURLs(urls, options.priority);
-      });
-    }
+  return new Promise((resolve, reject) => {
+    options = options || {priority: 'low'};
+    requestIdleCallback(() => {
+      // Prefetch an array of URLs if supplied (as an override)
+      if (options.urls !== undefined && options.urls.length > 0) {
+        prefetchURLs(options.urls, options.priority);
+        resolve(options.urls);
+      } else {
+        // Element to extract in-viewport links for
+        const el = options.el || document;
+        extractInViewportLinks(el).then(urls => {
+          prefetchURLs(urls, options.priority);
+          resolve(urls);
+        });
+      }
+    });
   });
 }

test/index.js

@@ -0,0 +1,22 @@
+import quicklink from '../src/index.mjs';
+import quicklinkDist from '../dist/quicklink.mjs';
+
+describe('quicklink', () => {
+  it('should be a function', () => {
+    expect(quicklink).toEqual(expect.any(Function));
+  });
+  it('should be compiled correctly', () => {
+    expect(quicklinkDist).toEqual(expect.any(Function));
+    expect(quicklinkDist).toHaveLength(1);
+  });
+  describe('prefetching', () => {
+    it('custom list of URLs', () => {
+      const p = quicklinkDist({urls: ['1.html', '2.html']});
+      p.then(r => {
+        expect(r.toHaveLength(2));
+      });
+    });
+  });
+});
+
+