Question

I have the following sample unit test that tries to mock java.nio.file.Files but this mock does not work and the code attempts to delete the sample path.

@Test
    public void testPostVisitDirectory() throws Exception {
        Path mockedPath = Paths.get("sample path");
        PowerMockito.mockStatic(Files.class);
        PowerMockito.doNothing().when(Files.class,
                PowerMockito.method(Files.class, "delete", Path.class));

        DeleteDirVisitor visitor = new DeleteDirVisitor(false);
        Assert.assertEquals("The was a problem visiting the file",
                FileVisitResult.CONTINUE,
                visitor.postVisitDirectory(mockedPath, null));
    }

Any idea what is wrong?

this is the content of the method visitor.postVisitDirectory

[...]
if (e == null) {
            Files.delete(dir);
            return FileVisitResult.CONTINUE;
        }
[...]

Thanks,

Answer 1

Did you add

@RunWith(PowerMockRunner.class)
@PrepareForTest(Files.class)

to your junit test class containing that method?

See powermock docs, the Writing tests section.

EDIT:

Hmmm, it seems like you’re doing everything right. Here’s what I’m running:

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;

import org.junit.Assert;
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(Files.class)
public class TestVisitor {
  public class PrintingVisitor extends SimpleFileVisitor<Path> {
    @Override
    public FileVisitResult postVisitDirectory(final Path dir, final IOException exc) throws IOException {
      Files.delete(dir);
      return FileVisitResult.CONTINUE;
    }
  }

  @Test
  public void testPostVisitDirectory() throws Exception {
    final Path mockedPath = Paths.get("sample path");

    /* Mocking */
    PowerMockito.mockStatic(Files.class);
    PowerMockito.doNothing().when(Files.class, PowerMockito.method(Files.class, "delete", Path.class));
    /* End Mocking */

    final PrintingVisitor visitor = new PrintingVisitor();
    Assert.assertEquals("The was a problem visiting the file", FileVisitResult.CONTINUE, visitor.postVisitDirectory(mockedPath, null));
  }
}

If I comment out the section labeled Mocking I get the NoSuchFileException. If I leave it, the test passes.

Perhaps post complete example which produces the error?