在Angular中测试Http POST方法，可以使用Angular的内置测试工具和一些模拟对象来模拟Http请求和响应。

首先，创建一个测试用的Angular组件，该组件将使用Http POST方法发送请求：

import { Component, OnInit } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Component({
  selector: 'app-post-example',
  templateUrl: './post-example.component.html',
  styleUrls: ['./post-example.component.css']
})
export class PostExampleComponent implements OnInit {

  constructor(private http: HttpClient) { }

  ngOnInit(): void {
  }

  postData() {
    const data = {
      name: 'John Doe',
      email: 'johndoe@example.com'
    };

    this.http.post('https://api.example.com/post', data)
      .subscribe(response => {
        console.log(response);
      });
  }

}

然后，创建一个测试用的Angular组件的测试文件，该文件将使用模拟的HttpClient对象来模拟Http请求和响应：

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';

import { PostExampleComponent } from './post-example.component';

describe('PostExampleComponent', () => {
  let component: PostExampleComponent;
  let fixture: ComponentFixture;
  let httpMock: HttpTestingController;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ PostExampleComponent ],
      imports: [ HttpClientTestingModule ]
    })
    .compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(PostExampleComponent);
    component = fixture.componentInstance;
    httpMock = TestBed.inject(HttpTestingController);
    fixture.detectChanges();
  });

  afterEach(() => {
    httpMock.verify();
  });

  it('should send POST request', () => {
    const testData = {
      name: 'John Doe',
      email: 'johndoe@example.com'
    };

    component.postData();

    const req = httpMock.expectOne('https://api.example.com/post');
    expect(req.request.method).toBe('POST');
    req.flush(testData);

    expect(component).toBeTruthy();
    expect(console.log).toHaveBeenCalledWith(testData);
  });

});

在上述测试用例中，使用HttpClientTestingModule来模拟HttpClient对象。在beforeEach块中，创建组件实例和HttpTestingController实例，并通过inject方法注入HttpTestingController。

在it块中，调用组件的postData方法来发送POST请求。然后，使用httpMock.expectOne来捕获发送的请求，并使用req.flush来模拟响应。最后，通过断言来验证是否发送了POST请求，并检查预期的响应。

在运行测试时，可以使用ng test命令来运行测试。