feat(@angular-devkit/schematics): add runSchematic and runExternalSchematic methods

These async method are a replacement for the Obervable based  `runSchematicAsync` and `runExternalSchematicAsync` methods.

DEPRECATED:
The Observable based `SchematicTestRunner.runSchematicAsync` and `SchematicTestRunner.runExternalSchematicAsync` method have been deprecated in favor of the Promise based SchematicTestRunner.runSchematic` and `SchematicTestRunner.runExternalSchematic`.

Author: alan-agius4

goldens/public-api/angular_devkit/schematics/testing/index.md

@@ -25,8 +25,12 @@ export class SchematicTestRunner {
     // (undocumented)
     registerCollection(collectionName: string, collectionPath: string): void;
     // (undocumented)
+    runExternalSchematic<SchematicSchemaT extends object>(collectionName: string, schematicName: string, opts?: SchematicSchemaT, tree?: Tree_2): Promise<UnitTestTree>;
+    // @deprecated (undocumented)
     runExternalSchematicAsync<SchematicSchemaT extends object>(collectionName: string, schematicName: string, opts?: SchematicSchemaT, tree?: Tree_2): Observable<UnitTestTree>;
     // (undocumented)
+    runSchematic<SchematicSchemaT extends object>(schematicName: string, opts?: SchematicSchemaT, tree?: Tree_2): Promise<UnitTestTree>;
+    // @deprecated (undocumented)
     runSchematicAsync<SchematicSchemaT extends object>(schematicName: string, opts?: SchematicSchemaT, tree?: Tree_2): Observable<UnitTestTree>;
     // (undocumented)
     get tasks(): TaskConfiguration[];

packages/angular_devkit/schematics/testing/schematic-test-runner.ts

@@ -7,7 +7,7 @@
  */
 
 import { logging, schema } from '@angular-devkit/core';
-import { Observable, of as observableOf } from 'rxjs';
+import { Observable, from, lastValueFrom, of as observableOf } from 'rxjs';
 import { map } from 'rxjs/operators';
 import {
   Collection,
@@ -78,34 +78,57 @@ export class SchematicTestRunner {
     this._engineHost.registerCollection(collectionName, collectionPath);
   }
 
-  runSchematicAsync<SchematicSchemaT extends object>(
+  async runSchematic<SchematicSchemaT extends object>(
     schematicName: string,
     opts?: SchematicSchemaT,
     tree?: Tree,
-  ): Observable<UnitTestTree> {
+  ): Promise<UnitTestTree> {
     const schematic = this._collection.createSchematic(schematicName, true);
     const host = observableOf(tree || new HostTree());
     this._engineHost.clearTasks();
 
-    return schematic
-      .call(opts || {}, host, { logger: this._logger })
-      .pipe(map((tree) => new UnitTestTree(tree)));
+    const newTree = await lastValueFrom(schematic.call(opts || {}, host, { logger: this._logger }));
+
+    return new UnitTestTree(newTree);
   }
 
-  runExternalSchematicAsync<SchematicSchemaT extends object>(
-    collectionName: string,
+  /**
+   * @deprecated since version 15.1. Use `runSchematic` instead.
+   */
+  runSchematicAsync<SchematicSchemaT extends object>(
     schematicName: string,
     opts?: SchematicSchemaT,
     tree?: Tree,
   ): Observable<UnitTestTree> {
+    return from(this.runSchematic(schematicName, opts, tree));
+  }
+
+  async runExternalSchematic<SchematicSchemaT extends object>(
+    collectionName: string,
+    schematicName: string,
+    opts?: SchematicSchemaT,
+    tree?: Tree,
+  ): Promise<UnitTestTree> {
     const externalCollection = this._engine.createCollection(collectionName);
     const schematic = externalCollection.createSchematic(schematicName, true);
     const host = observableOf(tree || new HostTree());
     this._engineHost.clearTasks();
 
-    return schematic
-      .call(opts || {}, host, { logger: this._logger })
-      .pipe(map((tree) => new UnitTestTree(tree)));
+    const newTree = await lastValueFrom(schematic.call(opts || {}, host, { logger: this._logger }));
+
+    return new UnitTestTree(newTree);
+  }
+
+  /**
+   * @deprecated since version 15.1. Use `runExternalSchematic` instead.
+   */
+  runExternalSchematicAsync<SchematicSchemaT extends object>(
+    collectionName: string,
+    schematicName: string,
+    opts?: SchematicSchemaT,
+    tree?: Tree,
+  ): Observable<UnitTestTree> {
+    return from(this.runExternalSchematic(collectionName, schematicName, opts, tree));
   }
 
   callRule(rule: Rule, tree: Tree, parentContext?: Partial<SchematicContext>): Observable<Tree> {