feat(@angular/cli): option to build and run only specified spec files

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

@@ -7,7 +7,7 @@
  */
 // tslint:disable
 // TODO: cleanup this file, it's copied as is from Angular CLI.
-
+import * as fs from 'fs';
 import * as path from 'path';
 import * as glob from 'glob';
 import * as webpack from 'webpack';
@@ -91,7 +91,38 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
       { pattern: path.join(ksmsPath, 'client.js'), watched: false }
     ], true);
   }
-
+  // generate new entry point with files matching provided glob
+  if (options.spec) {
+    const mainEntry = config.buildWebpack.webpackConfig.entry.main;
+    // could be temp file, but then it's not possible to update it unless the name is stored somewhere
+    const newMainEntry = config.buildWebpack.webpackConfig.entry.main = config.buildWebpack.webpackConfig.entry.main.replace('.ts', '.generated.ts');
+
+    // TODO: move logic below to separate util file
+    let template = fs.readFileSync(mainEntry).toString();
+    let pattern = options.spec; 
+    if (pattern.indexOf('.spec') === -1) {
+        pattern +='.spec.ts';
+    }
+    const files = glob.sync(pattern, { cwd: path.join(config.buildWebpack.projectRoot, config.buildWebpack.sourceRoot) });
+    if (!files.length) {
+        logger.error('Specified spec glob does not match any files'); 
+        process.exit(1); // TODO: any better way?
+        return;
+    }
+    const start = 'import \'';
+    const end = '\';';
+    const testCode = start + files.map(path=>`./${path.replace('.ts', '')}`).join(`${end}\n${start}`) + end;
+    // TODO: maybe a documented 'marker/comment' inside test.ts would be nicer
+    // or run typescript compiler and make changes based on the tree? 
+    template = template.replace(/declare\s+const\s+require:\s+any;/, '').replace(/require\.context\(.*/, '{keys:()=>({map:(_a:any)=>{}})};\n' + testCode);
+    fs.writeFileSync(newMainEntry, template);
+    // early exit if we are only supposed to update generated file
+    // so that we could avoid killing the runner and starting over
+    if (options.specUpdate) {
+      process.exit(0);
+      return;
+    }
+}
   // Add webpack config.
   const webpackConfig = config.buildWebpack.webpackConfig;
   const webpackMiddlewareConfig = {

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

@@ -87,6 +87,7 @@ export class KarmaBuilder implements Builder<KarmaBuilderSchema> {
         karmaOptions.buildWebpack = {
           root: getSystemPath(root),
           projectRoot: getSystemPath(projectRoot),
+          sourceRoot: builderConfig.sourceRoot,
           options: options as NormalizedKarmaBuilderSchema,
           webpackConfig: this.buildWebpackConfig(root, projectRoot, sourceRoot, host,
             options as NormalizedKarmaBuilderSchema),

packages/angular_devkit/build_angular/src/karma/schema.json

@@ -62,6 +62,15 @@
       "type": "string",
       "description": "Defines the build environment."
     },
+    "spec": {
+      "type": "string",
+      "description": "Glob of files to include"
+    },
+    "specUpdate": {
+      "type": "boolean",
+      "description": "Should this only update generated test file?",
+      "default": false
+    },
     "sourceMap": {
       "type": "boolean",
       "description": "Output sourcemaps.",