Minimal setup neccessary for a passing unit test

Author: Alex7Li

.eslintrc.json

@@ -0,0 +1,31 @@
+{
+  "env": {
+    "browser": true,
+    "es6": true,
+    "jasmine": true,
+    "node": true
+  },
+  "extends": [
+    "closure-es6",
+    "plugin:jasmine/recommended",
+    "google"
+  ],
+  "parserOptions": {
+    "sourceType": "module"
+  },
+  "plugins": [
+    "jasmine",
+    "closure"
+  ],
+  "rules": {
+    "prefer-rest-params": "off", // We don't want this, adds a polyfill
+    // This library requires this to be used in methods as part of the API,
+    // and sometimes it's useful to reference this in jasmine as there is
+    // special handling.
+    "no-invalid-this": "off",
+    "prefer-spread": "off", // As per Tagging ES6 guidelines.
+    "indent": "off", // Contradicts closure/indent.
+    // We use the hasOwn function to validate object properties.
+    "guard-for-in": "off"
+  }
+}

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "data-layer-helper"]
+	path = data-layer-helper
+	url = https://github.com/google/data-layer-helper

Gruntfile.js

@@ -27,7 +27,8 @@ module.exports = function(grunt) {
         },
         options: {
           js: [
-            'node_modules/google-closure-library/closure/goog/base.js'
+            'node_modules/google-closure-library/closure/goog/base.js',
+            'data-layer-helper/src/**/*.js',
           ],
           hide_warnings_for: 'google-closure-library',
           warning_level: 'VERBOSE',

data-layer-helper

@@ -8,10 +8,12 @@ module.exports = function(config) {
     // Automatically run tests for files matching these regex.
     files: [
       // ----------------- Third Party Dependencies ----------------------------
-      {pattern: 'node_modules/google-closure-library/closure/goog/base.js'},
-      // ------------------------ Source Files ---------------------------------
       // Dependencies must be listed before the file they are used in for
       // the googmodule preprocessor to function properly.
+      {pattern: 'node_modules/google-closure-library/closure/goog/base.js'},
+      {pattern: 'data-layer-helper/src/plain/is_plain_object.js'},
+      {pattern: 'data-layer-helper/src/helper/helper.js'},
+      // ------------------------ Source Files ---------------------------------
       {pattern: 'src/**/*.js'},
       // ------------------------- Test Files ----------------------------------
       'test/*_test.js'

karma.conf.js

@@ -0,0 +1,26 @@
+goog.module('measurementlibrary.measure');
+
+const {DataLayerHelper} = goog.require('helper');
+
+/**
+ * Listen to events passed to the current window.dataLayer (or a new one
+ * if none exist).
+ */
+function setup() {
+  /**
+   * @global {!Array} The data layer of the application, storing a record of
+   * events that have changed over time.
+   */
+  window.dataLayer = window.dataLayer || [];
+
+  /**
+   * @const {!DataLayerHelper} The DataLayerHelper to use with this application.
+   */
+  const helper = new DataLayerHelper(window.dataLayer);
+
+  // TODO
+}
+
+setup();
+
+exports = {setup};

src/measure.js

@@ -0,0 +1,73 @@
+goog.module('measurementlibrary.measure.testing.setup');
+goog.setTestOnly();
+
+const {setup} = goog.require('measurementlibrary.measure');
+
+let storageInterface;
+let eventProcessor;
+let measure;
+
+/**
+ * Run a test, once assuming that the measure snippet fired before the call
+ * to setup, then again assuming that the gtag snippet fired after the call
+ * to setup.
+ * @param {function} config The configuration done in the gtag code snippet
+ * @param {function} test The tests to run after both have fired
+ */
+const runInBothOrders = (config, test) => {
+  // The code snippet that is run asynchronously.
+  const snippet = () => {
+    window.dataLayer = window.dataLayer || [];
+    measure = function() {
+      dataLayer.push(arguments);
+    };
+    config();
+  };
+
+  // Test when the snippet fires first. Does not work now.
+  snippet();
+  setup();
+  test();
+
+  window.dataLayer = undefined;
+  // Test when the setup function fires first.
+  setup();
+  snippet();
+  test();
+};
+
+describe(`The behavior of the setup function of measurement library`, () => {
+
+  beforeEach(() => {
+    storageInterface = jasmine.createSpyObj('storageInterface',
+        ['get', 'set', 'config']);
+    eventProcessor = jasmine.createSpyObj('eventProcessor',
+        ['shouldPersist', 'processEvent', 'config']);
+  });
+
+  describe('the state immediately after calling config', () => {
+    it('does not call any eventProcessor functions when initially configured',
+        () => {
+          runInBothOrders(
+              /* config= */
+              () => measure('config', eventProcessor, storageInterface),
+              /* test=  */ () => {
+                expect(eventProcessor.shouldPersist).not.toHaveBeenCalled();
+                expect(eventProcessor.processEvent).not.toHaveBeenCalled();
+                expect(eventProcessor.config).not.toHaveBeenCalled();
+              });
+        });
+
+    it('does not call any storageInterface functions when initially configured',
+        () => {
+          runInBothOrders(
+              /* config= */
+              () => measure('config', eventProcessor, storageInterface),
+              /* test= */ () => {
+                expect(storageInterface.get).not.toHaveBeenCalled();
+                expect(storageInterface.set).not.toHaveBeenCalled();
+                expect(storageInterface.config).not.toHaveBeenCalled();
+              });
+        });
+  });
+});