How to mock a SharedPreferences using Mockito

So, because SharedPreferences comes from your context, it's easy:

final SharedPreferences sharedPrefs = Mockito.mock(SharedPreferences.class);final Context context = Mockito.mock(Context.class);Mockito.when(context.getSharedPreferences(anyString(), anyInt())).thenReturn(sharedPrefs);// no use context

for example, for getValidToken(Context context), the test could be:

@Beforepublic void before() throws Exception {    this.sharedPrefs = Mockito.mock(SharedPreferences.class);    this.context = Mockito.mock(Context.class);    Mockito.when(context.getSharedPreferences(anyString(), anyInt())).thenReturn(sharedPrefs);}@Testpublic void testGetValidToken() throws Exception {    Mockito.when(sharedPrefs.getString(anyString(), anyString())).thenReturn("foobar");    assertEquals("foobar", Auth.getValidToken(context));    // maybe add some verify();}

The following example shows how you might create a unit test that uses a mock Context object such as shared preference.

@RunWith(MockitoJUnitRunner.class)public class MProfileTest {   @Mock   Context mockContext;   @Mock   SharedPreferences mockPrefs;   @Mock   SharedPreferences.Editor mockEditor;   @Before   public void before() throws Exception {      Mockito.when(mockContext.getSharedPreferences(anyString(), anyInt())).thenReturn(mockPrefs);      Mockito.when(mockContext.getSharedPreferences(anyString(), anyInt()).edit()).thenReturn(mockEditor);      Mockito.when(mockPrefs.getString("YOUR_KEY", null)).thenReturn("YOUR_VALUE");   }   @Test   public void anyTest() {      // Any shared preference you can call      // Assert.assertTrue();      String val = _mockPrefs.getString("YOUR_KEY", null); // It returns YOUR_VALUE   }}

If you face any issues on importing mock framework just make sure you have added the depencencies in your app/build.gradle file.

https://developer.android.com/training/testing/unit-testing/local-unit-tests#setup

If you want to use real shared prefrence as your device by storing all the data in memory, follow the below code.

Get the MockSharedPreference.java file from this Gist https://gist.github.com/aslamanver/f74a2b3d450fda251d47a0d38b44edb7

@MockContext mockContext;MockSharedPreference mockPrefs;MockSharedPreference.Editor mockPrefsEditor;@Beforepublic void before() {    mockPrefs = new MockSharedPreference();    mockPrefsEditor = mockPrefs.edit();    Mockito.when(mockContext.getSharedPreferences(anyString(), anyInt())).thenReturn(mockPrefs);}

There is a better way to mock SharedPreferences, IMHO.I like Mockito, but it is unproductive to mock SharedPreferences in every test.

Luckily, we can use the shared-preferences-mock library. This library implements SharedPrefences on JVM, so it behaves like a real class. Moreover, it is possible to write local unit tests.

For your case:

import com.github.ivanshafran.sharedpreferencesmock.SPMockBuilder;class Test {    private Context context;    private SharedPreferences sharedPreferences;    @Before    public void setUp() {        this.sharedPreferences = new SPMockBuilder().createSharedPreferences();        this.context = Mockito.mock(Context.class);                 Mockito.when(context.getSharedPreferences(Constants.LOGGED_USER_PREFERENCES,0))            .thenReturn(sharedPreferences);    }    @Test    public void test() {        sharedPreferences.edit().putString(Constants.LOGGED_USERNAME, "admin").commit();        String value = Auth.getLoggedUser(context);        asssertEquals("admin", value);    }}

Add it to your root build.gradle at the end of repositories:

allprojects {    repositories {        maven { url 'https://jitpack.io' }    }}

Add the dependency:

dependencies {    testImplementation 'com.github.IvanShafran:shared-preferences-mock:1.0'}