Mockito之使用Answer

比眉伴天荒 2023-06-09 03:57 26阅读 0赞

**目录**

Answer的基本用法：

被测试类：DataSet.java

使用场景一:模拟Cursor

使用场景二：获取方法传入的参数，及验证参数或对参数断言

使用场景三：获取匿名内部类，对匿名内部类进行单元测试

--------------------

### Answer的基本用法： ###

Subject.java

public class Subject{
            public int getInt(){
                return 1;
            }
        }

测试用例

Answer answer = new Answer() {
                @Override
                public Object answer(InvocationOnMock invocation) throws Throwable {
                    String method = invocation.getMethod().getName();
                    if(method == "getInt"){
                        return 0;
                    }
                    return null;
                }
            };
            Subject subject = mock(Subject.class);
            when(subject.getInt()).thenAnswer(answer);
            System.out.println(subject.getInt());

输出结果：0

###  **被测试类：DataSet.java** ###

public class DataSet {
        private List<String> mData = new ArrayList(4);
        private static String TAG = "DataSet";
        ExecutorService mService;
        public List<String> getData(ContentResolver resolver){
            Uri uri = Uri.parse("uriString");
            List<String> data = new ArrayList(8);
            Cursor cursor = resolver.query(uri, null, null, null, null);
            if(cursor != null && cursor.getCount() > 0){
                while(cursor.moveToNext()){
                    data.add(cursor.getString(0));
                }
                mData = data;
                return data;
            }
            return null;
        }
    
        public void add(String s){
            if(s.startsWith("a")){
                mData.add(s);
                print(TAG, "info", s);
            }
        }
    
        public void print(String tag, String level, String info){
            System.out.println(tag + "    " + level + " : " + info);
        }
    
        public void saveData(){
            StringBuilder sb = new StringBuilder(64);
            for(String s : mData){
                sb.append(s);
            }
            final String data = sb.toString();
            if(data.length() > 0){
                Runnable runnable = new Runnable() {
                    @Override
                    public void run() {
                        File file = new File("data.txt");
                        if(file.exists()){
                            if(!file.delete()){
                                Log.e(TAG, "delete file failed!!!");
                                return;
                            }
                        }
                        FileWriter writer =  null;
                        try {
                            writer = new FileWriter(file);
                            BufferedWriter bw = new BufferedWriter(writer);
                            bw.write(data);
                            print(TAG, "info", "save data successed!!!");
                        } catch (FileNotFoundException e) {
                            e.printStackTrace();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }finally {
                            if(writer != null){
                                try {
                                    writer.close();
                                } catch (IOException e) {
                                    e.printStackTrace();
                                }
                            }
                        }
    
                    }
                };
                execute(runnable);
            }
    
    
        }
    
        public void execute(Runnable task){
            if(mService == null){
                mService = Executors.newSingleThreadExecutor();
            }
            mService.execute(task);
        }
    }

### 使用场景一:模拟Cursor ###

测试用例

final String[] arr = new String[]{"a", "b", "c", "d"};
            final int count = 8;
            Answer answer = new Answer() {
                int size = count;
                int pos = -1;
                String[] data = arr;
                @Override
                public Object answer(InvocationOnMock invocation) throws Throwable {
                    String method = invocation.getMethod().getName();
                    switch(method){
                        case "moveToNext":
                            return ++pos < size;
                        case "getCount":
                            return size;
                        case "getString":
                            int index = invocation.getArgument(0);
                            if(index == 0){
                                return String.valueOf(data[pos%data.length]);
                            }
                    }
                    return null;
                }
            };
            Cursor cursor = mock(Cursor.class, answer);
            ContentResolver contentResolver = mock(ContentResolver.class);
            when(contentResolver.query(any(Uri.class), (String[])isNull(), (String)isNull(),
                    (String[])isNull(), (String) isNull())).thenReturn(cursor);
    
            DataSet dataSet = new DataSet();
            //invoke getData()
            List result = dataSet.getData(contentResolver);
            //assert
            assertEquals(count, result.size());

### 使用场景二：获取方法传入的参数，及验证参数或对参数断言 ###

测试用例

String mStr;
        @Test
        public void should_str_equalsTo_mStr_when_add_with_str_startWith_a(){
            Answer answer = new Answer() {
                @Override
                public Object answer(InvocationOnMock invocation) throws Throwable {
                    int indexOfInfo = 2;
                    mStr = invocation.getArgument(indexOfInfo);
                    return null;
                }
            };
            DataSet dataSet = new DataSet();
            dataSet = spy(dataSet);
            doAnswer(answer).when(dataSet).print(anyString(), anyString(), anyString());
            String str = "ad";
            dataSet.add(str);
            //验证是否走入if分支
            assertEquals(str, mStr);
        }

### 使用场景三：获取匿名内部类，对匿名内部类进行单元测试 ###

测试用例

@Test
        public void should_call_print_with_String_contains_successed_when_saveData_with_mData_not_empty(){
            Answer answer = new Answer() {
                @Override
                public Object answer(InvocationOnMock invocation) throws Throwable {
                    //因为无法与runnable同步，无法验证run方法什么时候跑完，
                    // 所以就使用answer获取Runnable,并调用run方法
                    Runnable runnable = invocation.getArgument(0);
                    runnable.run();
                    return null;
                }
            };
            DataSet dataSet = new DataSet();
            dataSet = spy(dataSet);
            //string startWith "a",init DataSet#mData
            String data = "abb";
            dataSet.add(data);
            doAnswer(answer).when(dataSet).execute(any(Runnable.class));
            //invoke saveData()
            dataSet.saveData();
            //验证成功写完数据
            verify(dataSet, times(1)).print(anyString(), anyString(), contains("successed"));
        }