Mockito Mocked Class returns Null

Question

我正在使用Mockito来模拟我的JUnit测试类中的类，如下所示：

@Before
public void initialize(){
    DescribeHiveTable mockObj = Mockito.mock(DescribeHiveTable.class);
    String tableName = "clslog_assessments";
    String parentDirectoryPath ="src/test/resources/TEST18/RunFiles";
    String[] mockFeaturesArray1 = {"user_id","event_id"};
    ArrayList<String> mockFeaturesList1 = new ArrayList<String> (Arrays.asList(mockFeaturesArray1));
    when(mockObj.describeTable(tableName, parentDirectoryPath)).thenReturn(mockFeaturesList1);

然后我有了我的 Test 方法，它随后从内部调用 describeTable 方法。我检查了调用describeTable时的参数：tableName和parentDirectoryPath与我在 initalize 方法中定义的参数相同。

但是，我仍然得到一个空返回值。我不明白这种行为。也许我没有正确使用Mockito？

编辑

我的测试方法是这样的：

@Test
public void testComplexFeaturesExistingRun() {
String[] args = {masterConfigPath, runFilesPath, rootDir};
DriverClass driver = new DriverClass();
driver.main(args);
}

所以driver.main调用了describeTable方法，我试图模拟它的行为。

编辑 2

我的描述蜂巢表类是：

public class DescribeHiveTable {
public ArrayList<String> describeTable(String tableName, String parentDirectoryPath){
    String hiveQuery = "'describe " + tableName + "';";
    String bashScriptFile = parentDirectoryPath + "/describeTable.sh";
    .
    .
    .
        final Process process = builder.start();
        InputStream is = process.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        String line;
        while((line=br.readLine())!=null) {
            String[] output = line.split("t");
            columnList.add(output[0]);
       }
       return columnList;

这就是我调用描述表的方式：

DescribeHiveTable describeTable;
describeTable = new DescribeHiveTable();
ArrayList<String> columnList = describeTable.describeTable(tableName, runFile.getParent());

Answer 1

使用 Mockito 的方法是

private DescribeHiveTable mockObj; // must be accessible to Test methods
@Before
public void initialize(){
    this.mockObj = Mockito.mock(DescribeHiveTable.class);
    <etc>
}
@Test
public void testComplexFeaturesExistingRun() {
    /* test the objects that are set up to use this.mockObj,
       and not the usual type of DescribeHiveTable */
}

请注意，

describeTable = new DescribeHiveTable();

意味着您使用的是新的、未模拟的DescribeHiveTable，而不是模拟的mockObj。

但看起来您无法控制DriverClass使用的DescribeHiveTable实例？ 如果是这种情况，那么要么

• Mockito不会帮助你 - 或者你至少也必须嘲笑DriverClass;或者
• 您必须使用反射将DriverClass中的describeTable替换为 mockObj 。

Answer 2

您可以使用模拟

DescribeHiveTable 初始化DriverClass（前提是DescribeHiveTable是 DriverClass 的实例变量），如下所示：

public class TestClass{
@Mock
DescribeHiveTable mockObj;
// This will create a new instance of DriverClass with a mock of DescribeHiveTable
@InjectMocks
DriverClass driver;
@Before
    public void init() {
        MockitoAnnotations.initMocks(this);
        tableName = "clslog_assessments";
        parentDirectoryPath = "src/test/resources/TEST18/RunFiles";
        mockFeaturesArray1 = new String[] { "user_id", "event_id" };
        mockFeaturesList1 = new ArrayList<String>(
                Arrays.asList(mockFeaturesArray1));
        when(mockObj.describeTable(tableName, parentDirectoryPath)).thenReturn(
                mockFeaturesList1);
}
@Test
public void test() {
    // when(methodCall)
    assertEquals(mockFeaturesList1, driver.main());
}
}