Testing your Cloud BigQueryRead application with googlemock

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

Mocking a Successful BigQueryReadClient::GetServiceAccount() call

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

#include "google/cloud/bigquery/storage/v1/bigquery_read_client.h"
#include "google/cloud/bigquery/storage/v1/mocks/mock_bigquery_read_connection.h"
#include <gmock/gmock.h>

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

using ::google::cloud::bigquery_storage_v1_mocks::MockBigQueryReadConnection;
namespace bigquery = ::google::cloud::bigquery_storage_v1;

Create a mocking object for google::cloud::bigquery_storage_v1::BigQueryReadConnection:

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

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

  EXPECT_CALL(*mock, CreateReadSession)
      .WillOnce([&](google::cloud::bigquery::storage::v1::
                        CreateReadSessionRequest const& request) {
        EXPECT_EQ("test-project-name", request.parent());
        EXPECT_EQ("test-table-name", request.read_session().table());
        google::cloud::bigquery::storage::v1::ReadSession response;
        google::cloud::bigquery::storage::v1::ReadStream stream;
        stream.set_name("test-stream");
        *response.add_streams() = stream;
        return google::cloud::StatusOr<
            google::cloud::bigquery::storage::v1::ReadSession>(response);
      });

With the expectations in place, create a google::cloud::bigquery_storage_v1::BigQueryReadClient object:

  bigquery::BigQueryReadClient bigquery_client(mock);

And then make calls on the client as usual:

  google::cloud::bigquery::storage::v1::ReadSession read_session;
  read_session.set_table("test-table-name");
  int max_streams = 1;
  auto session = bigquery_client.CreateReadSession("test-project-name",
                                                   read_session, max_streams);

And then verify the results meet your expectations:

  EXPECT_TRUE(session.ok());
  EXPECT_EQ("test-stream", session->streams(0).name());

Full Listing

Finally we present the full code for this example:

 
#include "google/cloud/bigquery/storage/v1/bigquery_read_client.h"
#include "google/cloud/bigquery/storage/v1/mocks/mock_bigquery_read_connection.h"
#include <gmock/gmock.h>
 
namespace {
 
using ::google::cloud::bigquery_storage_v1_mocks::MockBigQueryReadConnection;
namespace bigquery = ::google::cloud::bigquery_storage_v1;
 
TEST(MockCreateReadSessionExample, CreateReadSession) {
  auto mock = std::make_shared<MockBigQueryReadConnection>();
 
  EXPECT_CALL(*mock, CreateReadSession)
      .WillOnce([&](google::cloud::bigquery::storage::v1::
                        CreateReadSessionRequest const& request) {
        EXPECT_EQ("test-project-name", request.parent());
        EXPECT_EQ("test-table-name", request.read_session().table());
        google::cloud::bigquery::storage::v1::ReadSession response;
        google::cloud::bigquery::storage::v1::ReadStream stream;
        stream.set_name("test-stream");
        *response.add_streams() = stream;
        return google::cloud::StatusOr<
            google::cloud::bigquery::storage::v1::ReadSession>(response);
      });
 
  bigquery::BigQueryReadClient bigquery_client(mock);
 
  google::cloud::bigquery::storage::v1::ReadSession read_session;
  read_session.set_table("test-table-name");
  int max_streams = 1;
  auto session = bigquery_client.CreateReadSession("test-project-name",
                                                   read_session, max_streams);
 
  EXPECT_TRUE(session.ok());
  EXPECT_EQ("test-stream", session->streams(0).name());
}
 
}  // namespace