feat(ivy): implement TestBed (#25369)

PR Close #25369

packages/core/testing/src/resolvers.ts

@@ -0,0 +1,73 @@
+/**
+ * @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, Directive, NgModule, Pipe, Type, ɵReflectionCapabilities as ReflectionCapabilities} from '@angular/core';
+
+import {MetadataOverride} from './metadata_override';
+import {MetadataOverrider} from './metadata_overrider';
+
+const reflection = new ReflectionCapabilities();
+
+/**
+ * Base interface to resolve `@Component`, `@Directive`, `@Pipe` and `@NgModule`.
+ */
+export interface Resolver<T> { resolve(type: Type<any>): T|null; }
+
+/**
+ * Allows to override ivy metadata for tests (via the `TestBed`).
+ */
+abstract class OverrideResolver<T> implements Resolver<T> {
+  private overrides = new Map<Type<any>, MetadataOverride<T>>();
+  private resolved = new Map<Type<any>, T|null>();
+
+  abstract get type(): any;
+
+  setOverrides(overrides: Array<[Type<any>, MetadataOverride<T>]>) {
+    this.overrides.clear();
+    overrides.forEach(([type, override]) => this.overrides.set(type, override));
+  }
+
+  getAnnotation(type: Type<any>): T|null {
+    return reflection.annotations(type).find(a => a instanceof this.type) || null;
+  }
+
+  resolve(type: Type<any>): T|null {
+    let resolved = this.resolved.get(type) || null;
+
+    if (!resolved) {
+      resolved = this.getAnnotation(type);
+      if (resolved) {
+        const override = this.overrides.get(type);
+        if (override) {
+          const overrider = new MetadataOverrider();
+          resolved = overrider.overrideMetadata(this.type, resolved, override);
+        }
+      }
+      this.resolved.set(type, resolved);
+    }
+
+    return resolved;
+  }
+}
+
+
+export class DirectiveResolver extends OverrideResolver<Directive> {
+  get type() { return Directive; }
+}
+
+export class ComponentResolver extends OverrideResolver<Component> {
+  get type() { return Component; }
+}
+
+export class PipeResolver extends OverrideResolver<Pipe> {
+  get type() { return Pipe; }
+}
+
+export class NgModuleResolver extends OverrideResolver<NgModule> {
+  get type() { return NgModule; }
+}