fixup! fix(@angular/cli): ng-update migrations not running with --migrate-only

Add tests

Author: devversion

packages/angular_devkit/schematics/tools/node-module-engine-host_spec.ts

@@ -0,0 +1,48 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import { SchematicEngine } from '@angular-devkit/schematics';
+import * as path from 'path';
+import * as fs from 'fs';
+import * as os from 'os';
+
+import { NodeModulesEngineHost } from './node-module-engine-host';
+
+const TMP_DIR = process.env['$TEST_TMPDIR'] || os.tmpdir();
+
+describe('NodeModulesEngineHost', () => {
+  let tmpDir: string|null = null;
+  let previousDir: string|null = null;
+
+  beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(TMP_DIR, 'angular-devkit-schematics-tools-node-module-engine-host'));
+    previousDir = process.cwd();
+    process.chdir(tmpDir!);
+  });
+
+  afterEach(() => process.chdir(previousDir!));
+
+  /** Creates a fake NPM module that can be used to test the node module engine host. */
+  function createFakeNpmModule() {
+    fs.mkdirSync(path.join(tmpDir!, 'node_modules'));
+    fs.mkdirSync(path.join(tmpDir!, 'node_modules/@angular/'));
+    fs.mkdirSync(path.join(tmpDir!, 'node_modules/@angular/core'));
+    fs.mkdirSync(path.join(tmpDir!, 'node_modules/@angular/core/schematics'));
+    fs.writeFileSync(path.join(tmpDir!, 'node_modules/@angular/core/package.json'), JSON.stringify({name: "@angular/core"}));
+    fs.writeFileSync(path.join(tmpDir!, 'node_modules/@angular/core/schematics/migrations.json'), JSON.stringify({schematics: {}}));
+  }
+
+  it('should properly create collections with explicit collection path', () => {
+    createFakeNpmModule();
+
+    const engineHost = new NodeModulesEngineHost();
+    const engine = new SchematicEngine(engineHost);
+
+    expect(() => engine.createCollection(path.join('@angular/core', './schematics/migrations.json'))).not.toThrow();
+  });
+});