莫基托 | JUnit | Avro：模拟 void 方法不起作用

Question

我写了一个avro序列化的方法，我想测试一下。

方法

@SneakyThrows
@Override
public byte[] serialize(String topic, T data) {
    try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
        writeSerializedAvro(stream, data, data.getSchema());
        return stream.toByteArray();
    } catch (IOException e) {
        throw new AvroSerializationException(e.getMessage(), e);
    }
}

private void writeSerializedAvro(ByteArrayOutputStream stream, T data, Schema schema) throws IOException {
    binaryEncoder = EncoderFactory.get().binaryEncoder(stream, binaryEncoder);
    DatumWriter<T> datumWriter = new GenericDatumWriter<>(schema);
    datumWriter.write(data, binaryEncoder);
    binaryEncoder.flush();
}

datumWriter.write 或binaryEncoder.flush() 可以抛出IOException。

在测试中，我想看看IOException是否被抛出，我的方法捕获它并将其包装在AvroSerializationException（我编写的一个类）中。

单元测试

    @Test(expected = AvroSerializationException.class)
public void testSerializeException() throws IOException {
    // Given 
// need to mock here

    // When
    serializer.serialize("", avroObject);
}

我尝试使用 doThrow().when() 方法模拟 GenericDatumWriter、BufferedBinaryEncoder 和 EncoderFactory，但对我没有任何效果。

BufferedBinaryEncoder binaryEncoder = Mockito.mock(BufferedBinaryEncoder.class);
Mockito.doThrow(new IOException()).when(binaryEncoder).flush();

和

    GenericDatumWriter datumWriter = Mockito.mock(GenericDatumWriter.class);
    Mockito.doThrow(new IOException()).when(datumWriter).write(any(), any());

但问题又回到了，我应该如何将这些对象传递给我的序列化程序，同时牢记最佳实践？

Answer 1

您需要首先使用 Mockito 模拟对象并在您的类中使用它，然后将引发异常，如下所示：

您的代码：

private DatumWriter<T> datumWriter = new GenericDatumWriter<>(schema);

@SneakyThrows
@Override
public byte[] serialize(String topic, T data) {
    try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
        writeSerializedAvro(stream, data, data.getSchema());
        return stream.toByteArray();
    } catch (IOException e) {
        throw new AvroSerializationException(e.getMessage(), e);
    }
}

private void writeSerializedAvro(ByteArrayOutputStream stream, T data, Schema schema) throws IOException {
    binaryEncoder = EncoderFactory.get().binaryEncoder(stream, binaryEncoder);
    datumWriter.write(data, binaryEncoder);
    binaryEncoder.flush();
}

public void setDatumWriter (DatumWriter datumWriter){
   this.datumWriter=datumWriter;
}

您的测试代码：

@Test(expected = AvroSerializationException.class)
public void testSerializeException() throws IOException {
    // Given 
    DatumWriter<YourClass> datumWriter = Mockito.mock(DatumWriter<YourClass>.class);
    when(datumWriter.write(anyObject(), anyObject())).thenThrow(IOException.class);
    
    serializer.setDatumWriter(datumWriter);  
   
    serializer.serialize("", avroObject);
}