"No provider for MdDialogRef!"

Question

Suppose I have this component:

@Component({
  selector: 'pizza-dialog',
  template: `
  <h1 md-dialog-title>Would you like to order pizza?</h1>

  <md-dialog-actions>
    <button (click)="dialogRef.close('yes')">Yes</button>
    <button md-dialog-close>No</button>
  </md-dialog-actions>
  `
})
export class PizzaDialog {
  constructor(public dialogRef: MdDialogRef<PizzaDialog>) { }
}

I've already imported MdDialog into my app module:

@NgModule({
  imports: [
    BrowserModule,
    MaterialModule.forRoot(),
    MdDialogModule.forRoot(),
  ],
  ...
})

Why would I get this error?

No provider for MdDialogRef!

Answer 1

You may have tried to use your dialog component in a template like this:

<pizza-dialog ...></pizza-dialog>

Delete that from your template and open the dialog using MdDialog.open() as is done here:

@Component({
  selector: 'pizza-component',
  template: `
  <button type="button" (click)="openDialog()">Open dialog</button>
  `
})
export class PizzaComponent {

  dialogRef: MdDialogRef<PizzaDialog>;

  constructor(public dialog: MdDialog) { }

  openDialog() {
    this.dialogRef = this.dialog.open(PizzaDialog, {
      disableClose: false
    });

    this.dialogRef.afterClosed().subscribe(result => {
      console.log('result: ' + result);
      this.dialogRef = null;
    });
  }
}

This code was copied from: https://github.com/angular/material2/blob/master/src/lib/dialog/README.md

Answer 2

You must not change your implementation. You can provide a Mock for the MdDialogRef. In the following example I fake the MdDialogRef with the MdDialogRefMock class and register it in the providers section:

import { async, ComponentFixture, TestBed } from "@angular/core/testing";
import { CUSTOM_ELEMENTS_SCHEMA } from "@angular/core";
import { MessageBoxYesNoComponent } from "./message-box-yes-no.component";
import { MdDialogRef } from "@angular/material";

class MdDialogRefMock {
}

describe("MessageBoxYesNoComponent", () => {
  let component: MessageBoxYesNoComponent;
  let fixture: ComponentFixture<MessageBoxYesNoComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ MessageBoxYesNoComponent ],
      schemas: [CUSTOM_ELEMENTS_SCHEMA],
      imports: [
      ],
      providers: [
        { provide: MdDialogRef, useClass: MdDialogRefMock }
      ]
    })
    .compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(MessageBoxYesNoComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it("should create", () => {
    expect(component).toBeTruthy();
  });
});

If you are using Jasmine, you can also create a Spy instead of creating the Fake-Class:

let mdDialogSpy = jasmine.createSpy('MdDialogRef');