Testing your Cloud IAM application with googlemock

This document describes how to test your own Cloud IAM application using the Cloud IAM C++ client library, Google Test and the Google Test Mocking Framework.

Mocking a Successful IAMClient::GetServiceAccount() call

First include the headers for the Cloud IAM Client, the mocking class, and the Google Mock framework:

#include "google/cloud/iam/admin/v1/iam_client.h"
#include "google/cloud/iam/admin/v1/mocks/mock_iam_connection.h"
#include <gmock/gmock.h>

The example uses a number of aliases to save typing and improve readability:

using ::google::cloud::iam_admin_v1_mocks::MockIAMConnection;
namespace iam = ::google::cloud::iam_admin_v1;

Create a mocking object for google::cloud::iam_admin_v1::IAMConnection:

  auto mock = std::make_shared<MockIAMConnection>();

It is customary to first setup the expectations for your mock, and then write the rest of the code:

  EXPECT_CALL(*mock, GetServiceAccount)
      .WillOnce([&](google::iam::admin::v1::GetServiceAccountRequest const&
                        request) {
        EXPECT_EQ("test-project-name", request.name());
        google::iam::admin::v1::ServiceAccount service_account;
        service_account.set_unique_id("test-unique-id");
        return google::cloud::StatusOr<google::iam::admin::v1::ServiceAccount>(
            service_account);
      });

With the expectations in place, create a google::cloud::iam_admin_v1::IAMClient object:

  iam::IAMClient iam_client(mock);

And then make calls on the client as usual:

  auto service_account = iam_client.GetServiceAccount("test-project-name");

And then verify the results meet your expectations:

  EXPECT_TRUE(service_account.ok());
  EXPECT_EQ("test-unique-id", service_account->unique_id());

Full Listing

Finally we present the full code for this example:

#include "google/cloud/iam/admin/v1/iam_client.h"
#include "google/cloud/iam/admin/v1/mocks/mock_iam_connection.h"
#include <gmock/gmock.h>

namespace {

using ::google::cloud::iam_admin_v1_mocks::MockIAMConnection;
namespace iam = ::google::cloud::iam_admin_v1;

TEST(MockGetServiceAccountExample, GetServiceAccount) {
  auto mock = std::make_shared<MockIAMConnection>();

  EXPECT_CALL(*mock, GetServiceAccount)
      .WillOnce([&](google::iam::admin::v1::GetServiceAccountRequest const&
                        request) {
        EXPECT_EQ("test-project-name", request.name());
        google::iam::admin::v1::ServiceAccount service_account;
        service_account.set_unique_id("test-unique-id");
        return google::cloud::StatusOr<google::iam::admin::v1::ServiceAccount>(
            service_account);
      });

  iam::IAMClient iam_client(mock);

  auto service_account = iam_client.GetServiceAccount("test-project-name");

  EXPECT_TRUE(service_account.ok());
  EXPECT_EQ("test-unique-id", service_account->unique_id());
}

}  // namespace