How do I mock a static method call from a nother static method in the same class? - powermock

Question

I have a utilities class wherein one static method calls another. I want to mock the called method but not the target method. Does anyone have an example?
I've got:
#RunWith(PowerMockRunner.class)
#PrepareForTest({SubjectUnderTest.class})
public class SubjectUnderTestTest {
...
SubjectUnderTest testTarget = PowerMockito.mock(SubjectUnderTest.class, Mockito.CALLS_REAL_METHODS);

Answer 1

Starting from the docs, with some minor tweaks, you can either mock or spy the static method, depending on what you need (spying seems a bit less verbose but has different syntax). You can find below a sample for both, based on PowerMockito 1.7.3 & Mockito 1.10.19.
Given the following simple class with the required 2 static methods:
public class ClassWithStaticMethods {
public static String doSomething() {
throw new UnsupportedOperationException("Nope!");
}
public static String callDoSomething() {
return doSomething();
}
}
You can do something like:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import static org.powermock.api.mockito.PowerMockito.*;
// prep for the magic show
#RunWith(PowerMockRunner.class)
#PrepareForTest(ClassWithStaticMethods.class)
public class ClassWithStaticMethodsTest {
#Test
public void shouldMockStaticMethod() {
// enable static mocking
mockStatic(ClassWithStaticMethods.class);
// mock the desired method
when(ClassWithStaticMethods.doSomething()).thenReturn("Did something!");
// can't use Mockito.CALLS_REAL_METHODS, so work around it
when(ClassWithStaticMethods.callDoSomething()).thenCallRealMethod();
// validate results
assertThat(ClassWithStaticMethods.callDoSomething(), is("Did something!"));
}
#Test
public void shouldSpyStaticMethod() throws Exception {
// enable static spying
spy(ClassWithStaticMethods.class);
// mock the desired method - pay attention to the different syntax
doReturn("Did something!").when(ClassWithStaticMethods.class, "doSomething");
// validate
assertThat(ClassWithStaticMethods.callDoSomething(), is("Did something!"));
}
}