test(@angular-devkit/build-angular): test karma on watch mode

packages/angular_devkit/build_angular/src/angular-cli-files/plugins/karma.ts

@@ -9,13 +9,15 @@
 // TODO: cleanup this file, it's copied as is from Angular CLI.
 
 import * as path from 'path';
-import * as fs from 'fs';
 import * as glob from 'glob';
 import * as webpack from 'webpack';
 const webpackDevMiddleware = require('webpack-dev-middleware');
 
-import { AssetPattern } from '../../browser/schema';
 import { KarmaWebpackFailureCb } from './karma-webpack-failure-cb';
+import { statsErrorsToString } from '../utilities/stats';
+import { getWebpackStatsConfig } from '../models/webpack-configs/stats';
+import { createConsoleLogger } from '@angular-devkit/core/node';
+import { logging } from '@angular-devkit/core';
 
 /**
  * Enumerate needed (but not require/imported) dependencies from this file
@@ -62,7 +64,7 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
     )
   }
   const options = config.buildWebpack.options;
-  const projectRoot = config.buildWebpack.projectRoot as string;
+  const logger: logging.Logger = config.buildWebpack.logger || createConsoleLogger();
   successCb = config.buildWebpack.successCb;
   failureCb = config.buildWebpack.failureCb;
 
@@ -93,7 +95,9 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
   // Add webpack config.
   const webpackConfig = config.buildWebpack.webpackConfig;
   const webpackMiddlewareConfig = {
-    logLevel: 'error', // Hide webpack output because its noisy.
+    // Hide webpack output because its noisy.
+    logLevel: 'error',
+    stats: false,
     watchOptions: { poll: options.poll },
     publicPath: '/_karma_webpack_/',
   };
@@ -147,9 +151,9 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
   try {
     compiler = webpack(webpackConfig);
   } catch (e) {
-    console.error(e.stack || e);
+    logger.error(e.stack || e)
     if (e.details) {
-      console.error(e.details);
+      logger.error(e.details)
     }
     throw e;
   }
@@ -175,9 +179,17 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
   }
 
   let lastCompilationHash: string | undefined;
+  const statsConfig = getWebpackStatsConfig();
   compiler.hooks.done.tap('karma', (stats: any) => {
-    // Refresh karma only when there are no webpack errors, and if the compilation changed.
-    if (stats.compilation.errors.length === 0 && stats.hash != lastCompilationHash) {
+    if (stats.compilation.errors.length > 0) {
+      const json = stats.toJson(config.stats);
+      // Print compilation errors.
+      logger.error(statsErrorsToString(json, statsConfig));
+      lastCompilationHash = undefined;
+      // Emit a failure build event if there are compilation errors.
+      failureCb && failureCb();
+    } else if (stats.hash != lastCompilationHash) {
+      // Refresh karma only when there are no webpack errors, and if the compilation changed.
       lastCompilationHash = stats.hash;
       emitter.refreshFiles();
     }

packages/angular_devkit/build_angular/src/karma/index.ts

@@ -97,6 +97,7 @@ export class KarmaBuilder implements Builder<KarmaBuilderSchema> {
           // When this workaround is removed, user projects need to be updated to use a Karma
           // version that has a fix for this issue.
           toJSON: () => { },
+          logger: this.context.logger,
         };
 
         // TODO: inside the configs, always use the project root and not the workspace root.

packages/angular_devkit/build_angular/test/karma/rebuilds_spec_large.ts

@@ -6,10 +6,12 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import { runTargetSpec } from '@angular-devkit/architect/testing';
-import { debounceTime, take, tap } from 'rxjs/operators';
+import { DefaultTimeout, runTargetSpec } from '@angular-devkit/architect/testing';
+import { Subject } from 'rxjs';
+import { debounceTime, delay, take, takeUntil, takeWhile, tap } from 'rxjs/operators';
 import { host, karmaTargetSpec } from '../utils';
 
+
 describe('Karma Builder watch mode', () => {
   beforeEach(done => host.initialize().toPromise().then(done, done.fail));
   afterEach(done => host.restore().toPromise().then(done, done.fail));
@@ -23,5 +25,83 @@ describe('Karma Builder watch mode', () => {
     ).toPromise();
 
     expect(res).toEqual({ success: true });
-  }, 30000);
+  });
+
+  it('recovers from compilation failures in watch mode', (done) => {
+    const overrides = { watch: true };
+    let buildCount = 0;
+    let phase = 1;
+
+    runTargetSpec(host, karmaTargetSpec, overrides, DefaultTimeout * 3).pipe(
+      debounceTime(500),
+      tap((buildEvent) => {
+        buildCount += 1;
+        switch (phase) {
+          case 1:
+            // Karma run should succeed.
+            // Add a compilation error.
+            expect(buildEvent.success).toBe(true);
+            // Add an syntax error to a non-main file.
+            host.appendToFile('src/app/app.component.spec.ts', `]]]`);
+            phase = 2;
+            break;
+
+          case 2:
+            // Karma run should fail due to compilation error. Fix it.
+            expect(buildEvent.success).toBe(false);
+            host.replaceInFile('src/app/app.component.spec.ts', `]]]`, '');
+            phase = 3;
+            break;
+
+          case 3:
+            // Karma run should succeed again.
+            expect(buildEvent.success).toBe(true);
+            phase = 4;
+            break;
+        }
+      }),
+      takeWhile(() => phase < 4),
+    ).toPromise().then(
+      () => done(),
+      () => done.fail(`stuck at phase ${phase} [builds: ${buildCount}]`),
+    );
+  });
+
+  it('does not rebuild when nothing changed', (done) => {
+    const overrides = { watch: true };
+    let buildCount = 0;
+    let phase = 1;
+
+    const stopSubject = new Subject();
+    const stop$ = stopSubject.asObservable().pipe(delay(5000));
+
+    runTargetSpec(host, karmaTargetSpec, overrides, DefaultTimeout * 3).pipe(
+      debounceTime(500),
+      tap((buildEvent) => {
+        buildCount += 1;
+        switch (phase) {
+          case 1:
+            // Karma run should succeed.
+            // Add a compilation error.
+            expect(buildEvent.success).toBe(true);
+            // Touch the file.
+            host.appendToFile('src/app/app.component.spec.ts', ``);
+            // Signal the stopper, which delays emission by 5s.
+            // If there's no rebuild within that time then the test is successful.
+            stopSubject.next();
+            phase = 2;
+            break;
+
+          case 2:
+            // Should never trigger this second build.
+            expect(true).toBeFalsy('Should not trigger second build.');
+            break;
+        }
+      }),
+      takeUntil(stop$),
+    ).toPromise().then(
+      () => done(),
+      () => done.fail(`stuck at phase ${phase} [builds: ${buildCount}]`),
+    );
+  });
 });