使用doReturn部分模拟PowerMockito的静态方法

Question

当我无法使用Mockito.when()时,如何使用PowerMockito中的doReturn模式来模拟静态方法？

我想测试以下静态方法:

public static PrintWriter openWriter(File file, Charset charset, boolean autoflush) throws FileNotFoundException {
      return openWriterHelper(new FileOutputStream(file), charset, autoflush);
   }

这是我的testMethod:

@Test
public void testOpenWriter_file_charset_autoflush() throws Throwable {
      Charset charset = mock(Charset.class);
      PrintWriter expected = mock(PrintWriter.class);
      File file = mock(File.class);
      FileOutputStream fos = mock(FileOutputStream.class);

      spy(IOHelper.class);
      whenNew(FileOutputStream.class).withArguments(file).thenReturn(fos);
      when(IOHelper.openWriterHelper(fos, charset, true)).thenReturn(expected);

      PrintWriter observed = IOHelper.openWriter(file, charset, true);
      assertEquals(expected, observed);

      verifyStatic();
      IOHelper.openWriterHelper(fos, charset, true);

}

问题是我无法在调用when时调用openWriterHelper,因为该方法在传递模拟OutputStream时会引发异常.

如果重要,这是openWriterHelper的代码:

public static PrintWriter openWriterHelper(OutputStream stream, Charset charset,
                                    boolean autoflush) {
  return new PrintWriter(new java.io.BufferedWriter(
        new java.io.OutputStreamWriter(stream, charset)), autoflush);

}

Answer 1

尝试

doReturn(expected).when(IOHelper.class, "openWriterHelper", file, charset, true);

或者

when(IOHelper.class, "openWriterHelper", file, charset, true).thenReturn(expected);

请参阅以下示例：http : //code.google.com/p/powermock/source/browse/trunk/modules/module-test/powermockito/junit4/src/test/java/samples/powermockito/junit4/partialmocking/StaticPartialMockingTest。 java?r=1366

Answer 2

替换这行代码：

when(IOHelper.openWriterHelper(fos, charset, true)).thenReturn(expected);

和

 doReturn(expected).when(IOHelper.class);
 IOHelper.openWriter(fos,charset, true);