fix(core): export inject() from @angular/core (#22389)

inject() supports the ngInjectableDef-based configuration of the injector
(otherwise known as tree-shakeable services). It was missing from the
exported API of @angular/core, this PR adds it.

The test added here is correct in theory, but may pass accidentally due
to the decorator side-effect replacing the inject() call at runtime. An
upcoming compiler PR will strip reified decorators from the output
entirely.

Fixes #22388

PR Close #22389

packages/compiler-cli/integrationtest/bazel/injectable_def/app/src/dep.ts

@@ -0,0 +1,41 @@
+/**
+ * @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 {Component, Injectable, NgModule} from '@angular/core';
+import {BrowserModule} from '@angular/platform-browser';
+import {ServerModule} from '@angular/platform-server';
+
+@Injectable()
+export class NormalService {
+}
+
+@Component({
+  selector: 'dep-app',
+  template: '{{found}}',
+})
+export class AppComponent {
+  found: boolean;
+  constructor(service: ShakeableService) { this.found = !!service.normal; }
+}
+
+@NgModule({
+  imports: [
+    BrowserModule.withServerTransition({appId: 'id-app'}),
+    ServerModule,
+  ],
+  declarations: [AppComponent],
+  bootstrap: [AppComponent],
+  providers: [NormalService],
+})
+export class DepAppModule {
+}
+
+@Injectable({scope: DepAppModule})
+export class ShakeableService {
+  constructor(readonly normal: NormalService) {}
+}

packages/compiler-cli/integrationtest/bazel/injectable_def/app/src/token.ts

@@ -6,11 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Component, Inject, InjectionToken, NgModule, forwardRef} from '@angular/core';
+import {Component, Inject, Injectable, InjectionToken, NgModule, forwardRef, inject} from '@angular/core';
 import {BrowserModule} from '@angular/platform-browser';
 import {ServerModule} from '@angular/platform-server';
 
-export interface IService { readonly data: string; }
+export interface IService { readonly dep: {readonly data: string;}; }
 
 @NgModule({})
 export class TokenModule {
@@ -18,7 +18,7 @@ export class TokenModule {
 
 export const TOKEN = new InjectionToken('test', {
   scope: TokenModule,
-  factory: () => new Service(),
+  factory: () => new Service(inject(Dep)),
 });
 
 
@@ -28,7 +28,7 @@ export const TOKEN = new InjectionToken('test', {
 })
 export class AppComponent {
   data: string;
-  constructor(@Inject(TOKEN) service: IService) { this.data = service.data; }
+  constructor(@Inject(TOKEN) service: IService) { this.data = service.dep.data; }
 }
 
 @NgModule({
@@ -37,10 +37,18 @@ export class AppComponent {
     ServerModule,
     TokenModule,
   ],
+  providers: [forwardRef(() => Dep)],
   declarations: [AppComponent],
   bootstrap: [AppComponent],
 })
 export class TokenAppModule {
 }
 
-export class Service { readonly data = 'fromToken'; }
+@Injectable()
+export class Dep {
+  readonly data = 'fromToken';
+}
+
+export class Service {
+  constructor(readonly dep: Dep) {}
+}

packages/compiler-cli/integrationtest/bazel/injectable_def/app/test/app_spec.ts

@@ -9,6 +9,7 @@
 import {enableProdMode} from '@angular/core';
 import {renderModuleFactory} from '@angular/platform-server';
 import {BasicAppModuleNgFactory} from 'app_built/src/basic.ngfactory';
+import {DepAppModuleNgFactory} from 'app_built/src/dep.ngfactory';
 import {HierarchyAppModuleNgFactory} from 'app_built/src/hierarchy.ngfactory';
 import {RootAppModuleNgFactory} from 'app_built/src/root.ngfactory';
 import {SelfAppModuleNgFactory} from 'app_built/src/self.ngfactory';
@@ -66,4 +67,14 @@ describe('ngInjectableDef Bazel Integration', () => {
       done();
     });
   });
+
+  it('can inject dependencies', done => {
+    renderModuleFactory(DepAppModuleNgFactory, {
+      document: '<dep-app></dep-app>',
+      url: '/',
+    }).then(html => {
+      expect(html).toMatch(/>true<\//);
+      done();
+    });
+  });
 });