Need help to write a unit test using Mockito and JUnit4

Question

Need help to write a unit test for the below code using Mockito and JUnit4,

public class MyFragmentPresenterImpl {        public Boolean isValid(String value) {         return !(TextUtils.isEmpty(value));       } } 

I tried below method: MyFragmentPresenter mMyFragmentPresenter

@Before public void setup(){     mMyFragmentPresenter=new MyFragmentPresenterImpl(); }  @Test public void testEmptyValue() throws Exception {     String value=null;     assertFalse(mMyFragmentPresenter.isValid(value)); } 

but it returns following exception,

java.lang.RuntimeException: Method isEmpty in android.text.TextUtils not mocked. See http://g.co/androidstudio/not-mocked for details. at android.text.TextUtils.isEmpty(TextUtils.java) at ....

Answer 1

Because of JUnit TestCase class cannot use Android related APIs, we have to Mock it.
Use PowerMockito to Mock the static class.

Add two lines above your test case class,

@RunWith(PowerMockRunner.class) @PrepareForTest(TextUtils.class) public class YourTest {  } 

And the setup code

@Before public void setup() {     PowerMockito.mockStatic(TextUtils.class);     PowerMockito.when(TextUtils.isEmpty(any(CharSequence.class))).thenAnswer(new Answer<Boolean>() {         @Override         public Boolean answer(InvocationOnMock invocation) throws Throwable {             CharSequence a = (CharSequence) invocation.getArguments()[0];             return !(a != null && a.length() > 0);         }     }); } 

That implement TextUtils.isEmpty() with our own logic.

Also, add dependencies in app.gradle files.

testCompile "org.powermock:powermock-module-junit4:1.6.2" testCompile "org.powermock:powermock-module-junit4-rule:1.6.2" testCompile "org.powermock:powermock-api-mockito:1.6.2" testCompile "org.powermock:powermock-classloading-xstream:1.6.2" 

Thanks Behelit's and Exception's answer.