feat(@angular-devkit/build-angular): drop support for `karma-coverage…

…-instanbul-reporter`

BREAKING CHANGE:

Support for `karma-coverage-instanbul-reporter` has been dropped in favor of the official karma coverage plugin `karma-coverage`.

packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma.ts

@@ -86,32 +86,11 @@ const init: any = (config: any, emitter: any) => {
   config.reporters.unshift('@angular-devkit/build-angular--event-reporter');
 
   // When using code-coverage, auto-add karma-coverage.
-  if (options.codeCoverage) {
-    config.plugins = config.plugins || [];
-    config.reporters = config.reporters || [];
-    const { plugins, reporters } = config;
-    const hasCoveragePlugin = plugins.some(isPlugin('karma-coverage', 'reporter:coverage'));
-    const hasIstanbulPlugin = plugins.some(
-      isPlugin('karma-coverage-istanbul-reporter', 'reporter:coverage-istanbul'),
-    );
-    const hasCoverageReporter = reporters.includes('coverage');
-    const hasIstanbulReporter = reporters.includes('coverage-istanbul');
-    if (hasCoveragePlugin && !hasCoverageReporter) {
-      reporters.push('coverage');
-    } else if (hasIstanbulPlugin && !hasIstanbulReporter) {
-      // coverage-istanbul is deprecated in favor of karma-coverage
-      reporters.push('coverage-istanbul');
-    } else if (!hasCoveragePlugin && !hasIstanbulPlugin) {
-      throw new Error('karma-coverage must be installed in order to run code coverage.');
-    }
-
-    if (hasIstanbulPlugin) {
-      logger.warn(
-        `'karma-coverage-istanbul-reporter' usage has been deprecated since version 11.\n` +
-          `Please install 'karma-coverage' and update 'karma.conf.js.' ` +
-          'For more info, see https://github.com/karma-runner/karma-coverage/blob/master/README.md',
-      );
-    }
+  if (
+    options.codeCoverage &&
+    !config.reporters.some((r: string) => r === 'coverage' || r === 'coverage-istanbul')
+  ) {
+    config.reporters.push('coverage');
   }
 
   // Add webpack config.
@@ -316,32 +295,6 @@ function fallbackMiddleware() {
   };
 }
 
-/**
- * Returns a function that returns true if the plugin identifier matches the
- * `moduleId` or `pluginName`. A plugin identifier can be either a string or
- * an object according to https://karma-runner.github.io/5.2/config/plugins.html
- * @param moduleId name of the node module (e.g. karma-coverage)
- * @param pluginName name of the karma plugin (e.g. reporter:coverage)
- */
-function isPlugin(moduleId: string, pluginName: string) {
-  return (plugin: string | {}): boolean => {
-    if (typeof plugin === 'string') {
-      if (!plugin.includes('*')) {
-        return plugin === moduleId;
-      }
-      const regexp = new RegExp(`^${plugin.replace('*', '.*')}`);
-      if (regexp.test(moduleId)) {
-        try {
-          require.resolve(moduleId);
-          return true;
-        } catch {}
-      }
-      return false;
-    }
-    return pluginName in plugin;
-  };
-}
-
 module.exports = {
   'framework:@angular-devkit/build-angular': ['factory', init],
   'reporter:@angular-devkit/build-angular--sourcemap-reporter': ['type', sourceMapReporter],