Testing

Developer tools are only used if they work. Testing is important as it discovers defects/bugs and improves the quality, reliability and functionality of software. This page details the Flipper APIs that can be used to effectively test plugins.

Writing tests

This section covers desktop plugins and client plugins.

Desktop plugins

Flipper uses Jest as a unit testing framework.

Writing unit tests for Flipper Desktop plugins is covered in detail in the Building a Desktop Plugin tutorial.

The flipper-plugin package provide several test utilities to make testing more convenient.

Client plugins

Android

Start by creating your first test file in this directory MyFlipperPluginTest.java. In the test method body, is the plugin to be tested as well as a FlipperConnectionMock.

The following example asserts that the plugin's connected status is what is expected:

@RunWith(RobolectricTestRunner.class)
public class MyFlipperPluginTest {

  @Test
  public void myTest() {
    final MyFlipperPlugin plugin = new MyFlipperPlugin();
    final FlipperConnectionMock connection = new FlipperConnectionMock();

    plugin.onConnect(connection);
    assertThat(plugin.connected(), equalTo(true));
  }
}

There are two mock classes that are used to construct tests: FlipperConnectionMock and FlipperResponderMock. Together these can be used to write very powerful tests to verify the end-to-end functionality of your plugin.

For example, you can test if, for a given incoming message, your plugin responds as expected:

@Test
public void myTest() {
  final MyFlipperPlugin plugin = new MyFlipperPlugin();
  final FlipperConnectionMock connection = new FlipperConnectionMock();
  final FlipperResponderMock responder = new FlipperResponderMock();

  plugin.onConnect(connection);

  final FlipperObject params = new FlipperObject.Builder()
      .put("phrase", "flipper")
      .build();
  connection.receivers.get("myMethod").onReceive(params, responder);

  assertThat(responder.successes, hasItem(
      new FlipperObject.Builder()
          .put("phrase", "ranos")
          .build()));
}

iOS

Start by creating your first test file MyFlipperPluginTests.cpp and import the testing utilities from fbsource//xplat/sonar/xplat:FlipperTestLib. These utilities mock out core pieces of the communication channel so that you can test your plugin in isolation.

#include <MyFlipperPlugin/MyFlipperPlugin.h>
#include <FlipperTestLib/FlipperConnectionMock.h>
#include <FlipperTestLib/FlipperResponderMock.h>

#include <folly/json.h>
#include <gtest/gtest.h>

namespace facebook {
namespace flipper {
namespace test {

TEST(MyFlipperPluginTests, testDummy) {
  EXPECT_EQ(1 + 1, 2);
}

} // namespace test
} // namespace flipper
} // namespace facebook

Following is a simple test using these mock utilities to create a plugin, send some data, and assert that the result is as expected:

TEST(MyFlipperPluginTests, testDummy) {
  std::vector<folly::dynamic> successfulResponses;
  auto responder = std::make_unique<FlipperResponderMock>(&successfulResponses);
  auto conn = std::make_shared<FlipperConnectionMock>();

  MyFlipperPlugin plugin;
  plugin.didConnect(conn);

  folly::dynamic message = folly::dynamic::object("param1", "hello");
  folly::dynamic expectedResponse = folly::dynamic::object("response", "Hi there");

  auto receiver = conn->receivers_["someMethod"];
  receiver(message, std::move(responder));

  EXPECT_EQ(successfulResponses.size(), 1);
  EXPECT_EQ(successfulResponses.back(), expectedResponse);
}

Running (Flipper) tests

This section covers running tests on the Flipper Desktop and with the Flipper SDK.

Flipper Desktop

Run yarn jest or yarn jest --watch in the desktop directory of your Flipper checkout.

Flipper SDK

Android (Java)

Gradle

In the root directory of the checkout:

./gradlew android:test

React Native

For details, see the Testing React Native Changes page.