fix(bazel): Remove angular devkit and restore ngc postinstall (#32946)

This commit removes `@angular-devkit/build-angular` from package.json
for a project that opts into Bazel. This is because the package adds a
dependency on node-sass, which is rejected by Bazel due to its absense.

This commit also appends to `scripts.postinstall` if it already exists.
This is needed because `ng new` in CLI v9 now automatically adds a
postinstall step for `ngcc`.

PR Close #32946

packages/bazel/src/schematics/ng-add/index.ts

@@ -76,6 +76,47 @@ function addDevDependenciesToPackageJson(options: Schema) {
   };
 }
 
+/**
+ * Remove packages that are not needed under Bazel.
+ * @param options
+ */
+function removeObsoleteDependenciesFromPackageJson(options: Schema) {
+  return (host: Tree) => {
+    const packageJson = 'package.json';
+    if (!host.exists(packageJson)) {
+      throw new Error(`Could not find ${packageJson}`);
+    }
+    const buffer = host.read(packageJson);
+    if (!buffer) {
+      throw new Error('Failed to read package.json content');
+    }
+    const content = buffer.toString();
+    const jsonAst = parseJsonAst(content) as JsonAstObject;
+    const deps = findPropertyInAstObject(jsonAst, 'dependencies') as JsonAstObject;
+    const devDeps = findPropertyInAstObject(jsonAst, 'devDependencies') as JsonAstObject;
+
+    const depsToRemove = [
+      '@angular-devkit/build-angular',
+    ];
+
+    const recorder = host.beginUpdate(packageJson);
+
+    for (const packageName of depsToRemove) {
+      const depNode = findPropertyInAstObject(deps, packageName);
+      if (depNode) {
+        removeKeyValueInAstObject(recorder, content, deps, packageName);
+      }
+      const devDepNode = findPropertyInAstObject(devDeps, packageName);
+      if (devDepNode) {
+        removeKeyValueInAstObject(recorder, content, devDeps, packageName);
+      }
+    }
+
+    host.commitUpdate(recorder);
+    return host;
+  };
+}
+
 /**
  * Append additional Javascript / Typescript files needed to compile an Angular
  * project under Bazel.
@@ -292,13 +333,19 @@ function addPostinstallToGenerateNgSummaries() {
     }
     const scripts = findPropertyInAstObject(jsonAst, 'scripts') as JsonAstObject;
     const recorder = host.beginUpdate(packageJson);
+    const ngcCommand = 'ngc -p ./angular-metadata.tsconfig.json';
     if (scripts) {
-      insertPropertyInAstObjectInOrder(
-          recorder, scripts, 'postinstall', 'ngc -p ./angular-metadata.tsconfig.json', 4);
+      const postInstall = findPropertyInAstObject(scripts, 'postinstall');
+      if (postInstall) {
+        const command = `${postInstall.value}; ${ngcCommand}`;
+        replacePropertyInAstObject(recorder, scripts, 'postinstall', command);
+      } else {
+        insertPropertyInAstObjectInOrder(recorder, scripts, 'postinstall', ngcCommand, 4);
+      }
     } else {
       insertPropertyInAstObjectInOrder(
           recorder, jsonAst, 'scripts', {
-            postinstall: 'ngc -p ./angular-metadata.tsconfig.json',
+            postinstall: ngcCommand,
           },
           2);
     }
@@ -329,6 +376,7 @@ export default function(options: Schema): Rule {
     return chain([
       addFilesRequiredByBazel(options),
       addDevDependenciesToPackageJson(options),
+      removeObsoleteDependenciesFromPackageJson(options),
       addPostinstallToGenerateNgSummaries(),
       backupAngularJson(),
       updateAngularJsonToUseBazelBuilder(options),

packages/bazel/src/schematics/ng-add/index_spec.ts

@@ -145,6 +145,29 @@ describe('ng-add schematic', () => {
     expect(json.devDependencies['@angular/bazel']).toBe('1.2.3');
   });
 
+  it('should remove unneeded dependencies', async() => {
+    const packageJson = JSON.parse(host.readContent('/package.json'));
+    packageJson.devDependencies['@angular-devkit/build-angular'] = '1.2.3';
+    host.overwrite('/package.json', JSON.stringify(packageJson));
+    host = await schematicRunner.runSchematicAsync('ng-add', defaultOptions, host).toPromise();
+    const content = host.readContent('/package.json');
+    const json = JSON.parse(content);
+    expect(json.devDependencies['angular-devkit/build-angular']).toBeUndefined();
+  });
+
+  it('should append to scripts.postinstall if it already exists', async() => {
+    const packageJson = JSON.parse(host.readContent('/package.json'));
+    packageJson['scripts'] = {
+      postinstall: 'angular rocks',
+    };
+    host.overwrite('/package.json', JSON.stringify(packageJson));
+    host = await schematicRunner.runSchematicAsync('ng-add', defaultOptions, host).toPromise();
+    const content = host.readContent('/package.json');
+    const json = JSON.parse(content);
+    expect(json.scripts['postinstall'])
+        .toBe('angular rocks; ngc -p ./angular-metadata.tsconfig.json');
+  });
+
   it('should not create Bazel workspace file', async() => {
     host = await schematicRunner.runSchematicAsync('ng-add', defaultOptions, host).toPromise();
     const {files} = host;