chore(test): set up integration testing

package.json

@@ -72,6 +72,7 @@
     "nsp": "^3.2.1",
     "pre-commit": "^1.2.2",
     "prettier": "^1.14.2",
+    "puppeteer": "^5.5.0",
     "standard-version": "^4.4.0",
     "webpack": "^4.17.2"
   },

test/integration/scenarios/basic-setup/basic-setup.test.js

@@ -0,0 +1,47 @@
+import ScenarioUtils from '../../utils/ScenarioUtils';
+
+const path = require('path');
+
+describe('A basic karma-webpack setup', () => {
+  let scenario;
+
+  const TEST_PATH = path.resolve(__dirname, './index.scenario.js');
+
+  const config = {
+    frameworks: ['webpack', 'mocha'],
+    files: [{ pattern: TEST_PATH }],
+    preprocessors: { [TEST_PATH]: ['webpack'] },
+    webpack: {},
+    browsers: ['ChromeHeadless'],
+    // Explicitly turn off reporters so the simulated test results are not confused with the actual results.
+    reporters: [],
+    port: 2389,
+    logLevel: 'OFF',
+    singleRun: true,
+  };
+
+  const plugins = ['karma-webpack', 'karma-chrome-launcher', 'karma-mocha'];
+
+  beforeAll((done) => {
+    ScenarioUtils.run(config, plugins)
+      .then((res) => {
+        scenario = res;
+        done();
+      })
+      .catch((err) => {
+        jest.fail('Karma run has failed with an error', err);
+      });
+  });
+
+  it('should have three successful test runs', () => {
+    expect(scenario.success).toBe(3);
+  });
+
+  it('should have one failed test run', () => {
+    expect(scenario.failed).toBe(1);
+  });
+
+  it('should complete with no errors', () => {
+    expect(scenario.error).toBe(false);
+  });
+});

test/integration/scenarios/basic-setup/index.scenario.js

@@ -0,0 +1,2 @@
+require('./js-source-example.js');
+require('./js-test-example.js');

test/integration/scenarios/basic-setup/js-source-example.js

@@ -0,0 +1,9 @@
+const AdvancedMath = {
+  add,
+};
+
+function add(a, b) {
+  return a + b;
+}
+
+export default AdvancedMath;

test/integration/scenarios/basic-setup/js-test-example.js

@@ -0,0 +1,24 @@
+import AdvancedMath from './js-source-example';
+
+const assert = require('assert');
+
+describe('test one example', () => {
+  it('an example passing test', () => {
+    assert.strictEqual(1, 1);
+  });
+});
+
+describe('test two example', () => {
+  it('an example failing test', () => {
+    assert.strictEqual(1, 0);
+  });
+});
+
+describe('bundled js content', () => {
+  it('should be able to bundle js content', () => {
+    assert.strictEqual(!!AdvancedMath.add, true);
+  });
+  it('should be able to interpret bundled js content', () => {
+    assert.strictEqual(AdvancedMath.add(1, 1), 2);
+  });
+});

test/integration/utils/KarmaWorker.js

@@ -0,0 +1,35 @@
+process.env.CHROME_BIN = require('puppeteer').executablePath();
+const karmaChromeLauncher = require('karma-chrome-launcher');
+const karmaMocha = require('karma-mocha');
+const { Server } = require('karma');
+
+const karmaWebpack = require('../../../lib/index');
+
+const PLUGINS = {
+  'karma-webpack': karmaWebpack,
+  'karma-mocha': karmaMocha,
+  'karma-chrome-launcher': karmaChromeLauncher,
+};
+
+function getPlugin(plugin) {
+  if (PLUGINS[plugin]) return PLUGINS[plugin];
+  throw new Error(
+    `Tried to load an unknown plugin [${plugin}] while running a karma scenario.`
+  );
+}
+
+process.on('message', ({ config, plugins }) => {
+  if (config.plugins) {
+    throw new Error(`
+Error: please specify plugins as the second argument of ScenarioUtils.run. \n
+available plugins: [${Object.keys(PLUGINS).join(',')}]}
+`);
+  }
+
+  const karmaConfiguration = config;
+  karmaConfiguration.plugins = plugins.map(getPlugin);
+  const server = new Server(karmaConfiguration);
+  // This will run once when the karma server completes running tests.
+  server.on('run_complete', (browsers, results) => process.send(results));
+  server.start();
+});

test/integration/utils/ScenarioUtils.js

@@ -0,0 +1,27 @@
+const { fork } = require('child_process');
+const path = require('path');
+
+// eslint-disable-next-line no-unused-vars
+const karma = require('karma');
+
+const ScenarioUtils = { run };
+
+/**
+ * This allows you to run a karma with a given configuration and list of plugins,
+ * on completion you will be returned a karma results object.
+ *
+ * @param {karma.ConfigOptions} config - The base karma configuration.
+ * @param {Array<String>} plugins - A list of plugins to be required
+ * @returns {Promise<karma.TestResults>}
+ */
+function run(config, plugins) {
+  return new Promise((resolve, reject) => {
+    fork(path.resolve(`${__dirname}/KarmaWorker.js`))
+      .on('close', reject)
+      .on('error', reject)
+      .on('message', resolve)
+      .send({ config, plugins });
+  });
+}
+
+export default ScenarioUtils;