HTTP Unit Testing

When writing unit tests using this HTTP framework, don't make requests to a real server. Instead, mock the HTTP transport and inject fake HTTP requests and responses. The pluggable HTTP transport layer of the Google HTTP Client Library for Java makes this flexible and simple to do.

Also, some useful testing utilities are included in the com.google.api.client.testing.http package (@Beta).

The following simple example generates a basic HttpResponse:

HttpTransport transport = new MockHttpTransport();
HttpRequest request = transport.createRequestFactory().buildGetRequest(HttpTesting.SIMPLE_GENERIC_URL);
HttpResponse response = request.execute();

The following example shows how to override the implementation of the MockHttpTransport class:

HttpTransport transport = new MockHttpTransport() {
  @Override
  public LowLevelHttpRequest buildRequest(String method, String url) throws IOException {
    return new MockLowLevelHttpRequest() {
      @Override
      public LowLevelHttpResponse execute() throws IOException {
        MockLowLevelHttpResponse response = new MockLowLevelHttpResponse();
        response.addHeader("custom_header", "value");
        response.setStatusCode(404);
        response.setContentType(Json.MEDIA_TYPE);
        response.setContent("{\"error\":\"not found\"}");
        return response;
      }
    };
  }
};
HttpRequest request = transport.createRequestFactory().buildGetRequest(HttpTesting.SIMPLE_GENERIC_URL);
HttpResponse response = request.execute();

For more examples, see the HttpResponseTest.java and HttpRequestTest.java files.