Mocked private method with PowerMock, but underlying method still gets called
Solution 1
From the PowerMock Private Method Example:
@RunWith(PowerMockRunner.class)
// We prepare PartialMockClass for test because it's final or we need to mock private or static methods
@PrepareForTest(PartialMockClass.class)
public class YourTestCase {
@Test
public void privatePartialMockingWithPowerMock() {
PartialMockClass classUnderTest = PowerMockito.spy(new PartialMockClass());
// use PowerMockito to set up your expectation
PowerMockito.doReturn(value).when(classUnderTest, "methodToMock", "parameter1");
// execute your test
classUnderTest.execute();
// Use PowerMockito.verify() to verify result
PowerMockito.verifyPrivate(classUnderTest, times(2)).invoke("methodToMock", "parameter1");
}
So to apply this to your code, I think it might become:
@RunWith(PowerMockRunner.class)
@PrepareForTest(CodeWithPrivateMethod.class)
public class PowerMock_Test {
@Test(expected = RuntimeException.class)
public void when_gambling_is_true_then_always_explode() throws Exception {
CodeWithPrivateMethod spy = PowerMockito.spy(new CodeWithPrivateMethod());
PowerMockito.doReturn(true).when(spy, "doTheGamble", anyString(), anyInt());
/* 1 */ PowerMockito.verifyPrivate(spy, times(0)).invoke("doTheGamble", anyString(), anyInt());
spy.meaningfulPublicApi();
/* 2 */ PowerMockito.verifyPrivate(spy, times(2)).invoke("doTheGamble", anyString(), anyInt());
}
}
I just coded that in the editor here. No tests have actually been run, and no bugs have been harmed in the crafting of this code.
Solution 2
ArtB,
Just pasting the complete code which works fine in my Eclipse IDE. I have only changed the expectation i said in my last post. Good luck.
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;
import static org.mockito.Matchers.anyInt;
import static org.mockito.Matchers.anyString;
import static org.powermock.api.support.membermodification.MemberMatcher.method;
import java.util.Random;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
@RunWith(PowerMockRunner.class)
@PrepareForTest(CodeWithPrivateMethod.class)
public class PowerMock_Test {
static boolean gambleCalled = false;
@Test(expected = RuntimeException.class)
public void when_gambling_is_true_then_always_explode() throws Exception {
CodeWithPrivateMethod spy = PowerMockito.spy(new CodeWithPrivateMethod());
// PowerMockito.doReturn(true).when(spy, "doTheGamble", anyString(), anyInt());
PowerMockito.doReturn(true).when(spy,
method(CodeWithPrivateMethod.class, "doTheGamble", String.class, int.class))
.withArguments(anyString(), anyInt());
assertThat( PowerMock_Test.gambleCalled, is(false) );
spy.meaningfulPublicApi();
assertThat( PowerMock_Test.gambleCalled, is(false) );
}
}
class CodeWithPrivateMethod {
public void meaningfulPublicApi() {
if (doTheGamble("Whatever", 1 << 3)) {
throw new RuntimeException("boom");
}
}
private boolean doTheGamble(String whatever, int binary) {
Random random = new Random(System.nanoTime());
boolean gamble = random.nextBoolean();
System.err.println( "\n>>> GAMBLE CALLED <<<\n" );
PowerMock_Test.gambleCalled = true;
return gamble;
}
}
Solution 3
ArtB,
Are you sure your code doesn't work (or) am i missing something here? I just replaced your method expectation with the following one the way Mike suggested and it works fine:
PowerMockito.doReturn(true).when(spy,
method(CodeWithPrivateMethod.class, "doTheGamble", String.class, int.class))
.withArguments(anyString(), anyInt());
I never used Powermockito but used Mockito a lot before.
Sled
A Java Developer who has worked at places ranging from a Fortune 100 company to a small start-up. Using Java for over 20 years.
Updated on May 19, 2020Comments
-
Sled almost 4 years
I am trying to mock out a private method that is making a JNDI call. When that method gets called from a unit test, it throws an exception^. I would like to mock-out that method for testing purposes. I used the sample code from another questions answer, and while the test passes, it seems that the underlying method still gets called. I inserted a
System.err.println()
in thedoTheGamble()
method, and it gets printed out to my console.Interesting enough, if I comment out the first
assertThat
, the test passes. ?:(So, how do I mock out a private method so that it does not get called?
import static org.hamcrest.core.Is.is; import static org.junit.Assert.assertThat; import static org.mockito.Matchers.anyInt; import static org.mockito.Matchers.anyString; import static org.powermock.api.mockito.PowerMockito.when; import static org.powermock.api.support.membermodification.MemberMatcher.method; import java.util.Random; import org.junit.Test; import org.junit.runner.RunWith; import org.powermock.api.mockito.PowerMockito; import org.powermock.core.classloader.annotations.PrepareForTest; import org.powermock.modules.junit4.PowerMockRunner; @RunWith(PowerMockRunner.class) @PrepareForTest(CodeWithPrivateMethod.class) public class PowerMock_Test { static boolean gambleCalled = false; @Test(expected = RuntimeException.class) public void when_gambling_is_true_then_always_explode() throws Exception { CodeWithPrivateMethod spy = PowerMockito.spy(new CodeWithPrivateMethod()); when(spy, method(CodeWithPrivateMethod.class, "doTheGamble", String.class, int.class)) .withArguments(anyString(), anyInt()) .thenReturn(true); /* 1 */ assertThat( PowerMock_Test.gambleCalled, is(false) ); spy.meaningfulPublicApi(); /* 2 */ assertThat( PowerMock_Test.gambleCalled, is(false) ); } } class CodeWithPrivateMethod { public void meaningfulPublicApi() { if (doTheGamble("Whatever", 1 << 3)) { throw new RuntimeException("boom"); } } private boolean doTheGamble(String whatever, int binary) { Random random = new Random(System.nanoTime()); boolean gamble = random.nextBoolean(); System.err.println( "\n>>> GAMBLE CALLED <<<\n" ); PowerMock_Test.gambleCalled = true; return gamble; } }
^ understandably, since my workspace does not support JNDI, only the production environment does
% I am using the latest versions of all the library, JUnit 4.10, Mockito 1.8.5, Hamcrest 1.1, Javassist 3.15.0, and PowerMock 1.4.10.