Mockito allows us to create mock objects. Since static method belongs to the class, there is no way in Mockito to mock static methods. However, we can use PowerMock along with Mockito framework to mock static methods.
PowerMock provides different modules to extend Mockito framework and run JUnit and TestNG test cases. Note that PowerMock doesn’t support JUnit 5 yet, so we will create JUnit 4 test cases. We will also learn how to integrate TestNG with Mockito and PowerMock.
We need following PowerMock dependencies for mocking static methods in Mockito.
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.Below is the final pom.xml from our project.
<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.journaldev.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>
Note that I am using 2.0.0-beta.5
version of PowerMock. This version supports Java 10, however, it’s still in beta so there might be some issues present in complex cases. When I tried to use current stable version 1.7.x
, I got the following errors.
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)
Here are GitHub issues opened for this exception - issue1 and issue2. Let’s create a simple class with a static method.
package com.journaldev.mockito.staticmethod;
public class Utils {
public static boolean print(String msg) {
System.out.println("Printing "+msg);
return true;
}
}
We need to do the following to integrate PowerMock with Mockito and JUnit 4.
@RunWith(PowerMockRunner.class)
annotation.@PrepareForTest
and provide classed to be mocked using PowerMock.PowerMockito.mockStatic()
for mocking class with static methods.PowerMockito.verifyStatic()
for verifying mocked methods using Mockito.Here is a complete example of mocking static method using Mockito and PowerMock in JUnit test case.
package com.journaldev.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());
}
}
For TestNG test cases, we don’t need to use @RunWith
annotation. We need test classes to extend PowerMockTestCase
so that PowerMockObjectFactory
is used to create test class instance.
package com.journaldev.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());
}
}
PowerMock provides extended features for Mockito, one of them is the ability to test static methods. It’s easily integrated with JUnit 4 and TestNG. However, there is no near-term support plan for JUnit 5.
You can download the complete project from our GitHub Repository.
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Can you add static void method please.
- asdfsad
Nice but I want to know how can we do the same with spring boot 2.3 and higher version.
- amar
Hello Pankaj , For mocking static methods , if we use PowerMockito , it will increse the memory consumption and soon we will get outofmemory on the application For mocking the static methods we can also use the approach of wrapping the static methods call in a sub -method and mocking it using spy . Hope I am correct .
- Sukriti Shrivastava