feat(bazel): ng_module produces bundle index (#22176)

It creates the bundle index .d.ts and .metadata.json files.
The names are based on the ng_module target.

PR Close #22176

packages/compiler-cli/integrationtest/bazel/ng_module/BUILD.bazel

@@ -0,0 +1,23 @@
+load("//packages/bazel:index.bzl", "ng_module")
+
+ng_module(
+    name = "test_module",
+    srcs = glob(["*.ts"]),
+    module_name = "some_npm_module",
+    deps = ["//packages/core"],
+)
+
+load(":extract_flat_module_index.bzl", "extract_flat_module_index")
+
+extract_flat_module_index(
+    name = "flat_module_index",
+    deps = [":test_module"],
+)
+
+load("@build_bazel_rules_nodejs//:defs.bzl", "jasmine_node_test")
+
+jasmine_node_test(
+    name = "test",
+    srcs = ["spec.js"],
+    data = [":flat_module_index"],
+)

packages/compiler-cli/integrationtest/bazel/ng_module/child.ts

@@ -0,0 +1,14 @@
+/**
+ * @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 {NgModule} from '@angular/core';
+import {Parent} from './parent';
+
+@NgModule({imports: [Parent]})
+export class Child {
+}

packages/compiler-cli/integrationtest/bazel/ng_module/extract_flat_module_index.bzl

@@ -0,0 +1,20 @@
+# 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
+"""Test utility to extract the "flat_module_metadata" from transitive Angular deps.
+"""
+
+def _extract_flat_module_index(ctx):
+  return [DefaultInfo(files = depset(transitive = [
+      dep.angular.flat_module_metadata
+      for dep in ctx.attr.deps
+      if hasattr(dep, "angular")
+  ]))]
+
+extract_flat_module_index = rule(
+    implementation = _extract_flat_module_index,
+    attrs = {
+      "deps": attr.label_list(),
+    },
+)

packages/compiler-cli/integrationtest/bazel/ng_module/index.ts

@@ -0,0 +1,9 @@
+/**
+ * @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
+ */
+
+export * from './child';

packages/compiler-cli/integrationtest/bazel/ng_module/parent.ts

@@ -0,0 +1,13 @@
+/**
+ * @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 {NgModule} from '@angular/core';
+
+@NgModule({})
+export class Parent {
+}

packages/compiler-cli/integrationtest/bazel/ng_module/spec.js

@@ -0,0 +1,31 @@
+/**
+ * @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
+ */
+
+const fs = require('fs');
+const PKG = 'angular/packages/compiler-cli/integrationtest/bazel/ng_module';
+describe('flat module index', () => {
+  describe('child metadata', () => {
+    it('should have contents', () => {
+      const metadata = fs.readFileSync(
+          require.resolve(`${PKG}/_test_module.bundle_index.metadata.json`), {encoding: 'utf-8'});
+      expect(metadata).toContain('"__symbolic":"module"');
+      expect(metadata).toContain('"__symbolic":"reference","module":"@angular/core"');
+      expect(metadata).toContain('"origins":{"Child":"./child","ɵa":"./parent"}');
+      expect(metadata).toContain('"importAs":"some_npm_module"');
+    });
+  });
+  describe('child typings', () => {
+    it('should have contents', () => {
+      const dts = fs.readFileSync(
+          require.resolve(`${PKG}/_test_module.bundle_index.d.ts`), {encoding: 'utf-8'});
+
+      expect(dts).toContain('export * from \'./index\';');
+      expect(dts).toContain('export { Parent as ɵa } from \'./parent\';');
+    });
+  });
+});