I have an image loader class and i need to test some static methods in it. Since Mockito does not support static methods i switched to Power Mockito. But the static method i am testing has a method call
Base64.encodeToString(byteArray, Base64.DEFAULT); To mock this i am using mockStatic method as below with @PrepareForTest annotation.
PowerMockito.mockStatic(Base64.class); But Android studio is returning me still returning me an error as below.
org.powermock.api.mockito.ClassNotPreparedException: The class android.util.Base64 not prepared for test. To prepare this class, add class to the '@PrepareForTest' annotation.
Below is my complete code.
Code to be tested:
import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.util.Base64; import android.widget.ImageView; public static String convertBitmapToBase64(Bitmap imageBitmap, boolean withCompression) { ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); imageBitmap.compress(Bitmap.CompressFormat.PNG, 120, byteArrayOutputStream); byte[] byteArray = byteArrayOutputStream.toByteArray(); return Base64.encodeToString(byteArray, Base64.DEFAULT); } Test class code
import android.graphics.Bitmap; import android.util.Base64; import org.junit.Before; import org.junit.runner.RunWith; import org.mockito.MockitoAnnotations; import org.powermock.api.mockito.PowerMockito; import org.powermock.core.classloader.annotations.PrepareForTest; import org.powermock.modules.junit4.PowerMockRunner; import org.testng.annotations.Test; @RunWith(PowerMockRunner.class) @PrepareForTest({Base64.class}) public class ImageLoaderTest { @Test public void testConvertBitmap(){ byte[] array = new byte[20]; PowerMockito.mockStatic(Base64.class); PowerMockito.when(Base64.encodeToString(array, Base64.DEFAULT)).thenReturn("asdfghjkl"); Bitmap mockedBitmap= PowerMockito.mock(Bitmap.class); String output = ImageLoaderUtils.convertBitmapToBase64(mockedBitmap); assert (!output.isEmpty()); } }
Gradle dependencies
testCompile 'junit:junit:4.12' testCompile 'org.powermock:powermock:1.6.5' testCompile 'org.powermock:powermock-module-junit4:1.6.5' testCompile 'org.powermock:powermock-api-mockito:1.6.5' 2 Answers
Answers 1
Short answer you can't. Here from the FAQ:
What are the limitations of Mockito
- Cannot mock final classes
- Cannot mock static methods
- Cannot mock final methods - their real behavior is executed without any exception. Mockito cannot warn you about mocking final methods so be vigilant.
Further information about this limitation:
Can I mock static methods?
No. Mockito prefers object orientation and dependency injection over static, procedural code that is hard to understand & change. If you deal with scary legacy code you can use JMockit or Powermock to mock static methods.
If you want to use PowerMock try like this:
@RunWith(PowerMockRunner.class) @PrepareForTest( { Base64.class }) public class YourTestCase { @Test public void testStatic() { mockStatic(Base64.class); when(Base64.encodeToString(argument)).thenReturn("expected result"); } } More on powermock test sample
Answers 2
Really trivially, I think you're calling prepareForTest incorrectly. It should be prepareForTest(Base64.class) not prepareForTest({Base64.class}) (note the squiggly braces in your code). Given the error you're getting, I think that's relevant.
