Angular - Material <mat-option> not visible in tests

I am working on Angular 9 with Material components. I want to show some values with in mat-select component.

Below is app.component.html

<h2> Angular - Material </h2>

<mat-form-field>
<mat-label>Type</mat-label>
<mat-select >
<mat-option value="string">Small text</mat-option>
<mat-option value="number">Number</mat-option>
<mat-option value="date">Date</mat-option>
</mat-select>
</mat-form-field>

<hr>


My app.component.ts

import { Component } from '@angular/core';

@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent {
title = 'angular-playground';
}


When I run app with ng serve then I can see select box with all options.



But when I try to test this component with karma ng test then I am not getting any options in the select box. I tried inspecting HTML DOM and I am not seeing any option tags with in select and there are no errors in the console.



app.component.spec.ts

import { TestBed, async } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { AppComponent } from './app.component';
import { MatFormFieldModule } from '@angular/material/form-field';
import {MatSelectModule} from '@angular/material/select';

describe('AppComponent', () => {
beforeEach(async(() => {
TestBed.configureTestingModule({
imports: [
RouterTestingModule, MatFormFieldModule, MatSelectModule
],
declarations: [
AppComponent
],
}).compileComponents();
}));

it('should create the app', () => {
const fixture = TestBed.createComponent(AppComponent);
const app = fixture.componentInstance;
expect(app).toBeTruthy();
});
});


This is a so basic angular application and I have a simple component with only select box. Not sure why it is not showing options in test.

Below is my app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MatFormFieldModule } from '@angular/material/form-field';
import {MatSelectModule} from '@angular/material/select';


@NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
AppRoutingModule,
BrowserAnimationsModule,
MatFormFieldModule,
MatSelectModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }


Please help me on this.

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