Mockito通过PowerMock来模拟静态方法

2 年 ago
清, 宇
6 minutes

Mockito 允许我们创建模拟对象。由于静态方法属于类，Mockito 无法模拟静态方法。然而，我们可以使用 PowerMock 结合 Mockito 框架来模拟静态方法。

使用PowerMock进行Mockito对静态方法的模拟

PowerMock提供了不同的模块来扩展Mockito框架并运行JUnit和TestNG测试用例。请注意，PowerMock尚不支持JUnit 5，因此我们将创建JUnit 4测试用例。我们还将学习如何将TestNG与Mockito和PowerMock集成。

PowerMock的依赖项

为了在Mockito中模拟静态方法，我们需要以下PowerMock依赖。

  • powermock-api-mockito2: This is the core PowerMock dependency and used to extend Mockito2 mocking framework. If you are using Mockito 1.x versions then use powermock-api-mockito module.
  • powermock-module-junit4: For running JUnit 4 test cases using PowerMock.
  • powermock-module-testng: For running TestNG test cases and supporting PowerMock.

以下是我们项目的最终pom.xml文件。

<project xmlns="https://maven.apache.org/POM/4.0.0"
	xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.Olivia.powermock</groupId>
	<artifactId>PowerMock-Examples</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<testng.version>6.14.3</testng.version>
		<junit4.version>4.12</junit4.version>
		<mockito-core.version>2.19.0</mockito-core.version>
		<powermock.version>2.0.0-beta.5</powermock.version>
		<java.version>10</java.version>
	</properties>

	<dependencies>
		<!-- TestNG -->
		<dependency>
			<groupId>org.testng</groupId>
			<artifactId>testng</artifactId>
			<version>${testng.version}</version>
			<scope>test</scope>
		</dependency>
		<!-- JUnit 4 -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>${junit4.version}</version>
			<scope>test</scope>
		</dependency>
		<!-- Mockito 2 -->
		<dependency>
			<groupId>org.mockito</groupId>
			<artifactId>mockito-core</artifactId>
			<version>${mockito-core.version}</version>
			<scope>test</scope>
		</dependency>
		<!-- PowerMock TestNG Module -->
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-testng</artifactId>
			<version>${powermock.version}</version>
			<scope>test</scope>
		</dependency>
		<!-- PowerMock JUnit 4.4+ Module -->
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4</artifactId>
			<version>${powermock.version}</version>
			<scope>test</scope>
		</dependency>
		<!-- PowerMock Mockito2 API -->
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-api-mockito2</artifactId>
			<version>${powermock.version}</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.7.0</version>
				<configuration>
					<source>${java.version}</source>
					<target>${java.version}</target>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-surefire-plugin</artifactId>
				<version>2.22.0</version>
				<dependencies>
					<dependency>
						<groupId>org.apache.maven.surefire</groupId>
						<artifactId>surefire-junit47</artifactId>
						<version>2.22.0</version>
					</dependency>
					<dependency>
						<groupId>org.apache.maven.surefire</groupId>
						<artifactId>surefire-testng</artifactId>
						<version>2.22.0</version>
					</dependency>
				</dependencies>
				<configuration>
					<additionalClasspathElements>
						<additionalClasspathElement>src/test/java/</additionalClasspathElement>
					</additionalClasspathElements>
					<!-- TestNG Test Fails when executed from command line with message
						"Cannot use a threadCount parameter less than 1" 
						Works when threadCount is explicitly specified 
						https://gist.github.com/juherr/6eb3e93e2db33979b7e90b63ddadc888-->
					<threadCount>5</threadCount>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

请注意，我正在使用PowerMock的2.0.0-beta.5版本。这个版本支持Java 10，但是它仍处于测试版，所以在复杂情况下可能会存在一些问题。当我尝试使用当前稳定版本1.7.x时，出现了以下错误。

java.lang.NoSuchMethodError: org.mockito.internal.handler.MockHandlerFactory.createMockHandler(Lorg/mockito/mock/MockCreationSettings;)Lorg/mockito/internal/InternalMockHandler;
	at org.powermock.api.mockito.internal.mockcreation.DefaultMockCreator.createMethodInvocationControl(DefaultMockCreator.java:114)
	at org.powermock.api.mockito.internal.mockcreation.DefaultMockCreator.createMock(DefaultMockCreator.java:69)
	at org.powermock.api.mockito.internal.mockcreation.DefaultMockCreator.mock(DefaultMockCreator.java:46)
	at org.powermock.api.mockito.PowerMockito.mockStatic(PowerMockito.java:73)

以下是为这个异常打开的GitHub问题 – 问题1和问题2。让我们创建一个简单的类，其中包含一个静态方法。

package com.Olivia.mockito.staticmethod;

public class Utils {

	public static boolean print(String msg) {
		System.out.println("Printing "+msg);
		return true;
	}
}

JUnit Mockito PowerMock 示例

我们需要做以下几步来将PowerMock与Mockito和JUnit 4进行集成。

  • Annotate test class with @RunWith(PowerMockRunner.class) annotation.
  • Annotate test class with @PrepareForTest and provide classed to be mocked using PowerMock.
  • Use PowerMockito.mockStatic() for mocking class with static methods.
  • Use PowerMockito.verifyStatic() for verifying mocked methods using Mockito.

这是一个在JUnit测试用例中使用Mockito和PowerMock来模拟静态方法的完整示例。

package com.Olivia.mockito.staticmethod;

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.mockito.ArgumentMatchers.anyString;
import static org.mockito.Mockito.atLeast;
import static org.mockito.Mockito.when;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Utils.class)
public class JUnit4PowerMockitoStaticTest{

	@Test
	public void test_static_mock_methods() {
		PowerMockito.mockStatic(Utils.class);
		when(Utils.print("Hello")).thenReturn(true);
		when(Utils.print("Wrong Message")).thenReturn(false);
		
		assertTrue(Utils.print("Hello"));
		assertFalse(Utils.print("Wrong Message"));
		
		PowerMockito.verifyStatic(Utils.class, atLeast(2));
		Utils.print(anyString());
	}
}

TestNG Mockito PowerMock 实例

在TestNG测试用例中，我们不需要使用@RunWith注解。我们需要测试类扩展PowerMockTestCase，这样才能使用PowerMockObjectFactory来创建测试类的实例。

package com.Olivia.mockito.staticmethod;

import static org.testng.Assert.assertFalse;
import static org.testng.Assert.assertTrue;

import static org.mockito.Mockito.*;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.testng.PowerMockTestCase;
import org.testng.annotations.Test;

@PrepareForTest(Utils.class)
public class TestNGPowerMockitoStaticTest extends PowerMockTestCase{

	@Test
	public void test_static_mock_methods() {
		PowerMockito.mockStatic(Utils.class);
		when(Utils.print("Hello")).thenReturn(true);
		when(Utils.print("Wrong Message")).thenReturn(false);
		
		assertTrue(Utils.print("Hello"));
		assertFalse(Utils.print("Wrong Message"));
		
		PowerMockito.verifyStatic(Utils.class);
		Utils.print("Hello");
		PowerMockito.verifyStatic(Utils.class, times(2));
		Utils.print(anyString());
	}
}

请用中文简述以下内容。

PowerMock提供了Mockito的扩展功能之一，就是能够测试静态方法。它可以轻松与JUnit 4和TestNG整合。然而，目前还没有针对JUnit 5的支持计划。

您可以从我们的GitHub代码库中下载完成的项目。

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