feat(repository): add getRepository function to mixin

packages/example-todo/test/acceptance/application.test.ts

@@ -121,11 +121,7 @@ describe('Application', () => {
   }
 
   async function givenTodoRepository() {
-    // TODO(bajtos) enhance RepositoryMixin to provide repository getter
-    // Example usage:
-    //  todoRepo = await app.getRepository<TodoRepository>(TodoRepository.name)
-    // See https://github.com/strongloop/loopback-next/issues/745
-    todoRepo = await app.get<TodoRepository>('repositories.TodoRepository');
+    todoRepo = await app.getRepository(TodoRepository);
   }
 
   async function givenTodoInstance(todo?: Partial<Todo>) {

packages/repository/src/repository-mixin.ts

@@ -62,6 +62,16 @@ export function RepositoryMixin<T extends Class<any>>(superClass: T) {
         .tag('repository');
     }
 
+    /**
+     * Retrieve the repository instance from the given Repository class
+     *
+     * @param repo The repository class to retrieve the instance of
+     */
+    // tslint:disable-next-line:no-any
+    async getRepository<R extends Repository<any>>(repo: Class<R>): Promise<R> {
+      return await this.get(`repositories.${repo.name}`);
+    }
+
     /**
      * Add the dataSource to this application.
      *
@@ -139,5 +149,9 @@ export function RepositoryMixin<T extends Class<any>>(superClass: T) {
 export interface AppWithRepository extends Application {
   // tslint:disable-next-line:no-any
   repository(repo: Class<any>): void;
+  // tslint:disable-next-line:no-any
+  getRepository<R extends Repository<any>>(repo: Class<R>): Promise<R>;
+  dataSource(dataSource: juggler.DataSource, name?: string): void;
+  component(component: Class<{}>): void;
   mountComponentRepository(component: Class<{}>): void;
 }

packages/repository/test/unit/repository-mixin/repository-mixin.test.ts

@@ -34,6 +34,23 @@ describe('RepositoryMixin', () => {
     expectNoteRepoToBeBound(myApp);
   });
 
+  it('mixed class has .getRepository()', () => {
+    const myApp = new AppWithRepoMixin();
+    expect(typeof myApp.getRepository).to.eql('function');
+  });
+
+  it('gets repository instance from app.getRepository()', async () => {
+    const myApp = new AppWithRepoMixin();
+    myApp
+      .bind('repositories.NoteRepo')
+      .toClass(NoteRepo)
+      .tag('repository');
+
+    const repoInstance = await myApp.getRepository(NoteRepo);
+
+    expect(repoInstance).to.be.instanceOf(NoteRepo);
+  });
+
   it('binds user defined component without repository', () => {
     class EmptyTestComponent {}