android - Mockito:如何将 getString 与 mockito 一起使用？

Question

我从谷歌关于如何测试您的 SharedPreferences 的示例中获得灵感通过创建 SharedPreferencesHelper 在此处编码类:

https://github.com/googlesamples/android-https://github.com/googlesamples/android-testing/blob/master/unit/BasicSample/app/src/main/java/com/example/android/testing/unittesting/BasicSample/SharedPreferencesHelper.java

您可以看到该类使用类中硬编码的实际字符串作为 sharedPreferences 的键。 - 这是类(class)的摘录:

public class SharedPreferencesHelper {

    // Keys for saving values in SharedPreferences.
    static final String KEY_NAME = "key_name";
    static final String KEY_DOB = "key_dob_millis";
    static final String KEY_EMAIL = "key_email";

    public boolean savePersonalInfo(SharedPreferenceEntry sharedPreferenceEntry){
        // Start a SharedPreferences transaction.
        SharedPreferences.Editor editor = mSharedPreferences.edit();
        editor.putString(KEY_NAME, sharedPreferenceEntry.getName());
        editor.putLong(KEY_DOB, sharedPreferenceEntry.getDateOfBirth().getTimeInMillis());
        editor.putString(KEY_EMAIL, sharedPreferenceEntry.getEmail());

        // Commit changes to SharedPreferences.
        return editor.commit();
    }

在使用他们的 SharedPreferencesHelperTest 进行测试时在这里上课，他们访问模拟的 sharedPreferences使用上述类中定义的相同变量:

https://github.com/googlesamples/android-testing/blob/master/unit/BasicSample/app/src/test/java/com/example/android/testing/unittesting/BasicSample/SharedPreferencesHelperTest.java

该类的摘录如下所示:

when(mMockSharedPreferences.getString(eq(SharedPreferencesHelper.KEY_NAME), anyString()))
            .thenReturn(mSharedPreferenceEntry.getName());
    when(mMockSharedPreferences.getString(eq(SharedPreferencesHelper.KEY_EMAIL), anyString()))
            .thenReturn(mSharedPreferenceEntry.getEmail());
    when(mMockSharedPreferences.getLong(eq(SharedPreferencesHelper.KEY_DOB), anyLong()))
            .thenReturn(mSharedPreferenceEntry.getDateOfBirth().getTimeInMillis());

谷歌这样做的方式允许他们绕过使用 context 的问题从 string.xml 资源文件中拉出一个字符串并在 sharedPreferences 中查询它就像通常使用 getString() 发生的情况一样，即:

mSharedPreferences.getString(context.getString(R.string.name),"");

但是，我读到不可能使用 context.getString因为它是一个 final 方法，mockito 不能模拟 final 方法:

Mockito - Overriding a method that takes primitive parameters

然后我如何使用 mockito 对 getString 的任何方法进行单元测试？ ？任何带有 getString 的方法将不起作用，我的单元测试将失败。

这是我为 SharedPreferences 编写的类(class)我想用 sharedPreferences 测试它用 getStrings 编写的键:

public class SharedPreferencesHelper {

    // The injected SharedPreferences implementation to use for persistence.
    private final SharedPreferences mSharedPreferences;
    private Context context;

    public SharedPreferencesHelper(SharedPreferences sharedPreferences, Context context) {
        mSharedPreferences = sharedPreferences;
        this.context = context;
    }

    public boolean saveName(String name) {
        // Start a SharedPreferences transaction.
        SharedPreferences.Editor editor = mSharedPreferences.edit();
        editor.putString(context.getString(R.string.name), name);
        return editor.commit();
    }

    public String fetchName() {
        // Start a SharedPreferences transaction.
        return mSharedPreferences.getString(context.getString(R.string.name),"");
    }

    public boolean saveGender(String gender) {
        SharedPreferences.Editor editor = mSharedPreferences.edit();
        editor.putString(context.getString(R.string.gender), gender);
        return editor.commit();
    }

}

这是我为上述类编写的测试 - 它与谷歌的 SharedPreferencesHelperTest 非常相似:

@RunWith(MockitoJUnitRunner.class)
public class SharedPreferencesHelperTest {

    private static final String TEST_NAME = "Test name";

    private SharedPreferencesHelper mMockSharedPreferencesHelper;

    @Mock
    SharedPreferences mMockSharedPreferences;
    @Mock
    SharedPreferences.Editor mMockEditor;
    @Mock
    MockContext context;

    @Before
    public void setUp() throws Exception {
        // Create a mocked SharedPreferences.
        mMockSharedPreferencesHelper = createMockSharedPreference();
    }

    @Test
    public void testSaveName() throws Exception {
        boolean success = mMockSharedPreferencesHelper.saveName(TEST_NAME);
        Timber.e("success " + success);
        assertThat("Checking that name was saved... returns true = " + success,
                success, is(true));
        String name = mMockSharedPreferencesHelper.fetchName();
        Timber.e("name " + name);
        assertThat("Checking that name has been persisted and read correctly " + name,
                TEST_NAME,
                is(name));
    }

    /**
     * Creates a mocked SharedPreferences.
     */
    private SharedPreferencesHelper createMockSharedPreference() {
        // Mocking reading the SharedPreferences as if mMockSharedPreferences was previously written
        // correctly.
        when(mMockSharedPreferences.getString(Matchers.eq("name"), anyString()))
                .thenReturn(TEST_NAME);
        when(mMockSharedPreferences.getString(Matchers.eq("gender"), anyString()))
                .thenReturn("M");
        // Mocking a successful commit.
        when(mMockEditor.commit()).thenReturn(true);
        // Return the MockEditor when requesting it.
        when(mMockSharedPreferences.edit()).thenReturn(mMockEditor);
        return new SharedPreferencesHelper(mMockSharedPreferences, context);
    }
}

运行测试失败，因为我使用了 getString在我的 SharedPreferencesHelper类(class)。如果我对键进行硬编码，我将不会收到错误，即:

public String fetchName() {
    // Start a SharedPreferences transaction.
    return mSharedPreferences.getString("name","");
}

不应该在代码中硬编码字符串，那么我该如何解决这个难题？

Answer 1

您可以通过不使用 Context 来获取字符串资源，而是使用 Resources 类来解决这个问题。 Resources 具有相同的 getString 方法，但它不是最终的。

https://developer.android.com/reference/android/content/res/Resources.html#getString(int)

或者，您可以试用 Robolectric，它可以解决这个问题，因为它们实现了上下文。

http://robolectric.org/