PowerMockito无法模拟FileInputStream的构造函数

Question

I am trying to mock the constructor for the FileInputStream and I have the following code:

@RunWith(PowerMockRunner.class)
@PrepareForTest(FileInputStream.class)
public class DBUtilsTest {

    @Test(expected = FileNotFoundException.class)
    public void readTableMetadataFileNotFoundException() throws Exception {
        try {
            PowerMockito.whenNew(FileInputStream.class)
                    .withParameterTypes(String.class)
                    .withArguments(Matchers.any(String.class))
                    .thenThrow(FileNotFoundException.class);

            PowerMock.replayAll();

            TableMetadata tableMeta = DBUtils
                    .readTableMetadata(path);
        } finally {
            PowerMock.verifyAll();
        }
    }
}
public class DBUtils {
    public static TableMetadata readTableMetadata(String metadataPath)
            throws FileNotFoundException, IOException {

        Properties properties = new Properties();
        FileInputStream is = new FileInputStream(metadataPath); 
        properties.load(is);
        .....
    }
}

Though, the test fails with java.lang.AssertionError: Expected exception: java.io.FileNotFoundException

It seems that the constructor isn't really mocked and the exception does not get thrown. Can anyone give any help with this issue?

Answer 1

I found out that I should prepare for test the tested class, meaning DBUtils, and not the FileInputStream class.

@PrepareForTest(DBUtils.class)

some useful examples can be found here .