我有这个代码，我想测试，并获得最大坑覆盖率，但我不能杀死的否定条件，如果（关闭）变种。我还使用mockito抛出一些异常。

public static void copyBytes(InputStream in, OutputStream out, int buffSize, boolean close) throws IOException {
        try {
            copyBytes(in, out, buffSize);
            if (close) {
                out.close();
                out = null;
                in.close();
                in = null;
            }
        } finally {
            if (close) {
                closeStream(out);
                closeStream(in);
            }
        }
    }

这是我的案例测试：

@Test
        public void mockOutputCopyBytes1False(){
            try{
                OutputStream outputStream = Mockito.mock(OutputStream.class);
                doThrow(new IOException()).when(outputStream).close();
                copyBytes(createInputStream(), outputStream, 50, false);
                outputStream.write(10);
            }catch (Exception e){
                e.printStackTrace();
                Assert.assertEquals(IOException.class, e.getClass());
            }
        }

    @Test
    public void mockOutputCopyBytes1True(){
        try{
            OutputStream outputStream = Mockito.mock(OutputStream.class);
            doThrow(new IOException()).when(outputStream).close();
            copyBytes(createInputStream(), outputStream, 50, true);
            outputStream.write(10);
        }catch (Exception e){
            e.printStackTrace();
            Assert.assertEquals(IOException.class, e.getClass());
        }
    }