Build Spring Unit test by using PowerMock with Mockito

sometimes we need to test final class or static class, at this time we need powermock.

1, update pom.xml to import powermock

<dependency>
		<groupId>org.powermock</groupId>
		<artifactId>powermock-core</artifactId>
		<scope>test</scope>
	</dependency>
	<dependency>
		<groupId>org.powermock</groupId>
		<artifactId>powermock-module-junit4</artifactId>
		<scope>test</scope>
	</dependency>
	<dependency>
		<groupId>org.powermock</groupId>
		<artifactId>powermock-api-mockito</artifactId>
		<scope>test</scope>
	</dependency>

 2. then we can use powermock in unit test like below:

in this example, ReadInputRegistersResponse is a final class.

@RunWith(PowerMockRunner.class)
@PrepareForTest(ReadInputRegistersResponse.class)
public class InverterDetailsResponseTest {

private ReadInputRegistersResponse mockModbusResp;

    @test
    public void test1() {
        mockModbusResp = mock(ReadInputRegistersResponse.class);
        // ......
}

but sometimes in unit test, we need have @RunWith(SpringJUnit4ClassRunner.class), when we still need powermock, we will avoid @RunWith(PowerMockRunner.class).

below is the example how to avoid @RunWith(PowerMockRunner.class), but still use powermock.

1. it is simple , just add : PowerMockAgent.initializeIfNeeded() method.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"/inverter-persistent-config.xml"})
public class TcpModbusServiceTest extends AbstractInverterTest {
    static {
        PowerMockAgent.initializeIfNeeded();
    }
}

Note:

at this time the mocked class should be a local variable like this:

private void mockModbusResponse() throws CommunicationException {
        ReadInputRegistersResponse mockModbusResp = mock(ReadInputRegistersResponse.class);
// ... ... ...
}

2. if you are using maven and want to run test by mvn test, then you need to add below lines in build config as well:

<build>
<plugins>
		    <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <excludes>
			          <exclude>**/*IT.java</exclude>
			          <exclude>**/Abstract*.java</exclude>
			        </excludes>
                    <argLine>
                        -javaagent:${settings.localRepository}/org/powermock/powermock-module-javaagent/${powermock.version}/powermock-module-javaagent-${powermock.version}.jar
                    </argLine>
                    <useSystemClassloader>true</useSystemClassloader>
                </configuration>
            </plugin>
</plugins>
</build>

3. in pom.xml dependency is a bit different:

<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4-rule-agent</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
            <groupId>org.powermock.tests</groupId>
            <artifactId>powermock-tests-utils</artifactId>
            <scope>test</scope>
        </dependency>		
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-core</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-api-mockito</artifactId>
			<scope>test</scope>
		</dependency>

that's it.