fix(@schematics/angular): application migration should migrate karma builder package

The `use-application-builder` update migration will now attempt to migrate
the `karma` builder to use the `@angular/build` package if no other
`@angular-devkit/build-angular` usage is present.

Author: clydin

Diff for: packages/schematics/angular/migrations/use-application-builder/migration.ts

@@ -217,6 +217,7 @@ function updateProjects(tree: Tree, context: SchematicContext) {
         case Builders.Application:
         case Builders.DevServer:
         case Builders.ExtractI18n:
+        case Builders.Karma:
         case Builders.NgPackagr:
           // Ignore application, dev server, and i18n extraction for devkit usage check.
           // Both will be replaced if no other usage is found.
@@ -242,6 +243,13 @@ function updateProjects(tree: Tree, context: SchematicContext) {
           case Builders.ExtractI18n:
             target.builder = '@angular/build:extract-i18n';
             break;
+          case Builders.Karma:
+            target.builder = '@angular/build:karma';
+            // Remove "builderMode" option since the builder will always use "application"
+            for (const [, karmaOptions] of allTargetOptions(target)) {
+              delete karmaOptions['builderMode'];
+            }
+            break;
           case Builders.NgPackagr:
             target.builder = '@angular/build:ng-packagr';
             break;

Diff for: packages/schematics/angular/migrations/use-application-builder/migration_spec.ts

@@ -40,6 +40,15 @@ function createWorkSpaceConfig(tree: UnitTestTree) {
   tree.create('/package.json', JSON.stringify({}, undefined, 2));
 }
 
+function addWorkspaceTarget(tree: UnitTestTree, targetName: string, targetEntry: unknown): void {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const workspaceContent = tree.readJson('/angular.json') as Record<string, any>;
+
+  workspaceContent['projects']['app']['architect'][targetName] = targetEntry;
+
+  tree.overwrite('/angular.json', JSON.stringify(workspaceContent));
+}
+
 describe(`Migration to use the application builder`, () => {
   const schematicName = 'use-application-builder';
   const schematicRunner = new SchematicTestRunner(
@@ -102,6 +111,25 @@ describe(`Migration to use the application builder`, () => {
     });
   });
 
+  it(`should remove 'builderMode' from karma options`, async () => {
+    addWorkspaceTarget(tree, 'test', {
+      'builder': Builders.Karma,
+      'options': {
+        'builderMode': 'detect',
+        'polyfills': ['zone.js', 'zone.js/testing'],
+        'tsConfig': 'projects/app-a/tsconfig.spec.json',
+      },
+    });
+
+    const newTree = await schematicRunner.runSchematic(schematicName, {}, tree);
+    const {
+      projects: { app },
+    } = JSON.parse(newTree.readContent('/angular.json'));
+
+    const { builderMode } = app.architect['test'].options;
+    expect(builderMode).toBeUndefined();
+  });
+
   it('should remove tilde prefix from CSS @import specifiers', async () => {
     // Replace outputPath
     tree.create(