Master Android UI Testing with Espresso

Contents

• Chapter 1: Introduction to Android Espresso
• Chapter 2: Setting up Android Espresso
• Chapter 3: Writing Test Cases with Android Espresso
• Chapter 4: Running and Analyzing Test Results
• Chapter 5: Best Practices and Tips

Chapter 1: Introduction to Android Espresso

Android Espresso is an Android UI testing framework provided by Google. It allows you to test the UI in the same way as actual users, greatly helping to improve the quality of the application.

Why Espresso?

Espresso is loved by many developers for the following reasons:

• It performs tests while using the app in the same way as real users.
• Allows you to write test codes in a concise and easy-to-read manner.
• It integrates well with Android Studio, making it easy to set up and run tests.

What You Will Learn

In this guide, you will learn how to perform UI testing using Espresso. To do this, the following topics are covered:

• How to set up Espresso
• How to write test cases using Espresso
• How to analyze test results
• Best practices for testing with Espresso

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Chapter 2: Setting up Android Espresso

Before using Android Espresso, you need to set up your environment first. In this chapter, we will take a closer look at how to set up Espresso in Android Studio.

Prerequisites

Before setting up Espresso, you need the following:

• Installation of Android Studio (Version 3.0 or higher recommended)
• Android device or emulator (API level 18 or higher)

Adding Espresso Dependencies

First, you need to add Espresso dependencies to your project's build.gradle file.

<dependencies>
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
</dependencies>

Syncing the Project

After adding the dependencies, you need to sync the project. To do this, click 'Sync Project with Gradle Files' from the top menu of Android Studio.

Checking the Setup

To check if the setup has been completed correctly, let's run a simple test.

<@RunWith(AndroidJUnit4.class)>
public class MainActivityTest {
    @Test
    public void testActivityShouldBeLaunched() {
        ActivityScenario.launch(MainActivity.class);
    }
}

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Chapter 3: Writing Test Cases with Android Espresso

In this chapter, we will take a detailed look at how to write actual test cases using Android Espresso.

Understanding Espresso Test Recorder

The Espresso Test Recorder is a feature that converts all actions performed in your app into test code. This makes it easy to write test cases.

Creating a Test Case

The basic format for writing a test case with Espresso is as follows:

<@RunWith(AndroidJUnit4.class)>
public class ExampleInstrumentedTest {
    @Rule
    public ActivityTestRule<MainActivity> activityRule = new ActivityTestRule<>(MainActivity.class);

    @Test
    public void testExample() {
        onView(withId(R.id.exampleView)).perform(click());
        onView(withId(R.id.exampleView)).check(matches(isDisplayed()));
    }
}

Explaining the Test Case

In the above test case, a test is performed to click on the View with the ID 'exampleView' and check if that View is displayed on the screen.

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Chapter 4: Running and Analyzing Test Results

In this chapter, we will learn how to run the test cases we have written and how to analyze the results.

Running the Test

To run the test, select 'Run' > 'Run 'app'' from the top menu of Android Studio.

Viewing the Results

Once the test is complete, you can check the results by clicking the 'Run' tab at the bottom of Android Studio. This tab shows the status of each test and, in the case of failed tests, the cause is displayed.

Analyzing the Results

To analyze the test results, you need to understand the cause of the failed tests and find appropriate modifications to solve them. Through the test results, you can find out which parts of the app are not working as expected and which parts need improvement.

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Chapter 5: Best Practices and Tips

In this chapter, we will learn about the best practices and tips to follow when performing UI testing using Android Espresso.

Write Small, Focused Tests

It is good to write small-scale, focused tests on specific functions. By doing so, you can clearly understand exactly what each test is testing, and it is also easy to maintain the test.

Use Idling Resources for Synchronization

It is recommended to use Idling Resources for synchronization between asynchronous operations in the app and test code. This can increase the stability of the test.

Keep Tests Independent

Each test should be able to be performed independently. If there is a dependency between tests, the failure of one test can affect other tests, so care should be taken.

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