使用 power mockito 模拟方法调用 - org.powermock.api.mockito.ClassNot

问题描述

我有一个图像加载器类，我需要在其中测试一些静态方法.由于 Mockito 不支持静态方法，我切换到 Power Mockito.但是我正在测试的静态方法有一个方法调用

 Base64.encodeToString(byteArray, Base64.DEFAULT);

为了模拟这个，我使用 mockStatic 方法如下，带有@PrepareForTest 注释.

 PowerMockito.mockStatic(Base64.class);

但 Android Studio 正在返回我仍然返回如下错误.

org.powermock.api.mockito.ClassNotPreparedException:类android.util.Base64 未准备好进行测试.要准备这堂课，请添加'@PrepareForTest' 注释的类.

下面是我的完整代码.

要测试的代码:

导入android.graphics.Bitmap；导入android.graphics.BitmapFactory；导入 android.util.Base64；导入android.widget.ImageView；公共静态字符串 convertBitmapToBase64(位图 imageBitmap, boolean withCompression) {ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();imageBitmap.compress(Bitmap.CompressFormat.PNG, 120, byteArrayOutputStream);byte[] byteArray = byteArrayOutputStream.toByteArray();返回 Base64.encodeToString(byteArray, Base64.DEFAULT);}

测试类代码

导入android.graphics.Bitmap；导入 android.util.Base64；导入 org.junit.Before；导入 org.junit.runner.RunWith；导入 org.mockito.MockitoAnnotations；导入 org.powermock.api.mockito.PowerMockito；导入 org.powermock.core.classloader.annotations.PrepareForTest；导入 org.powermock.modules.junit4.PowerMockRunner；导入 org.testng.annotations.Test；@RunWith(PowerMockRunner.class)@PrepareForTest({Base64.class})公共类 ImageLoaderTest {@测试公共无效 testConvertBitmap(){字节[]数组=新字节[20]；PowerMockito.mockStatic(Base64.class);PowerMockito.when(Base64.encodeToString(array, Base64.DEFAULT)).thenReturn("asdfghjkl");位图 mockedBitmap=PowerMockito.mock(Bitmap.class);字符串输出 = ImageLoaderUtils.convertBitmapToBase64(mockedBitmap);断言 (!output.isEmpty());}

}

Gradle 依赖项

testCompile 'junit:junit:4.12'testCompile 'org.powermock:powermock:1.6.5'testCompile 'org.powermock:powermock-module-junit4:1.6.5'testCompile 'org.powermock:powermock-api-mockito:1.6.5'

简答你不能.这里来自 FAQ:

Mockito 有什么限制

• 无法模拟最终课程
• 无法模拟静态方法
• 不能模拟最终方法 - 它们的真实行为会毫无例外地执行.Mockito 无法警告您模拟最终方法，所以保持警惕.

有关此限制的更多信息:

我可以模拟静态方法吗?

没有.Mockito 更喜欢面向对象和依赖注入难以理解的静态程序代码改变.如果你处理可怕的遗留代码，你可以使用 JMockit 或 Powermock 来模拟静态方法.

如果你想使用 PowerMock 试试这样:

@RunWith(PowerMockRunner.class)@PrepareForTest( { Base64.class })公共类 YourTestCase {@测试公共无效测试静态(){模拟静态(Base64.class)；when(Base64.encodeToString(argument)).thenReturn("预期结果");}}

在 Mockito 2 现在可以模拟最终类和最终方法.这是一个可选的选项.您需要使用以下内容创建文件 src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker:

mock-maker-inline

编辑 2:由于 Mockito 3.4.0 现在可以 模拟静态方法:

try (MockedStatic mocked = mockStatic(Base64.class)) {mocked.when(() -> Base64.encodeToString(eq(array), eq(Base64.DEFAULT))).thenReturn("bar");assertEquals("bar", Base64.encodeToString(array, Base64.DEFAULT));mocked.verify(() -> Base64.encodeToString(any(), anyIn());}

此外，您可以直接添加为依赖项 org.mockito:mockito-inline:+ 并避免手动创建 or.mockito.plugins.MockMaker 文件

从 Mockito 3.5.0 开始，您还可以 模拟对象构造.

I have an image loader class and i need to test some static methods in it. Since Mockito does not support static methods i switched to Power Mockito. But the static method i am testing has a method call

 Base64.encodeToString(byteArray, Base64.DEFAULT);

To mock this i am using mockStatic method as below with @PrepareForTest annotation.

 PowerMockito.mockStatic(Base64.class);

But Android studio is returning me still returning me an error as below.

org.powermock.api.mockito.ClassNotPreparedException: The class android.util.Base64 not prepared for test. To prepare this class, add class to the '@PrepareForTest' annotation.

Below is my complete code.

Code to be tested:

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Base64;
import android.widget.ImageView;

  public static String convertBitmapToBase64(Bitmap imageBitmap, boolean withCompression) {
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    imageBitmap.compress(Bitmap.CompressFormat.PNG, 120, byteArrayOutputStream);
    byte[] byteArray = byteArrayOutputStream.toByteArray();
    return Base64.encodeToString(byteArray, Base64.DEFAULT);
}

Test class code

import android.graphics.Bitmap;
import android.util.Base64;
import org.junit.Before;
import org.junit.runner.RunWith;
import org.mockito.MockitoAnnotations;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import org.testng.annotations.Test;

@RunWith(PowerMockRunner.class)
@PrepareForTest({Base64.class})
public class ImageLoaderTest  {
@Test
   public void testConvertBitmap(){
    byte[] array = new byte[20];
    PowerMockito.mockStatic(Base64.class);
    PowerMockito.when(Base64.encodeToString(array, Base64.DEFAULT)).thenReturn("asdfghjkl");
    Bitmap mockedBitmap= PowerMockito.mock(Bitmap.class);
    String output = ImageLoaderUtils.convertBitmapToBase64(mockedBitmap);
    assert (!output.isEmpty());
}

}

Gradle dependencies

testCompile 'junit:junit:4.12'
testCompile 'org.powermock:powermock:1.6.5'
testCompile 'org.powermock:powermock-module-junit4:1.6.5'
testCompile 'org.powermock:powermock-api-mockito:1.6.5'

Short answer you can't. Here from the FAQ:

What are the limitations of Mockito

• Cannot mock final classes
• Cannot mock static methods
• Cannot mock final methods - their real behavior is executed without any exception. Mockito cannot warn you about mocking final methods so be vigilant.

Further information about this limitation:

Can I mock static methods?

No. Mockito prefers object orientation and dependency injection over static, procedural code that is hard to understand & change. If you deal with scary legacy code you can use JMockit or Powermock to mock static methods.

If you want to use PowerMock try like this:

@RunWith(PowerMockRunner.class)
@PrepareForTest( { Base64.class })
public class YourTestCase {
    @Test
    public void testStatic() {
        mockStatic(Base64.class);
        when(Base64.encodeToString(argument)).thenReturn("expected result");
    }
}

EDIT: In Mockito 2 it's now possible to mock final Class and final Method. It's an opt-in option. You need to create the file src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker with the following content:

mock-maker-inline

EDIT 2: Since Mockito 3.4.0 its now possible to mock static method too:

try (MockedStatic mocked = mockStatic(Base64.class)) {
    mocked.when(() -> Base64.encodeToString(eq(array), eq(Base64.DEFAULT))).thenReturn("bar");
    assertEquals("bar", Base64.encodeToString(array, Base64.DEFAULT));
    mocked.verify(() -> Base64.encodeToString(any(), anyIn());
}

Furthermore you can directly add as a dependency org.mockito:mockito-inline:+ and avoid manually create the or.mockito.plugins.MockMaker file

Since Mockito 3.5.0 you can also mock object construction.

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