JUnit and Surefire Parallel Tests - ForkCount & ThreadCount

Question

I'm running Selenium tests on the Selenium Grid using the Surefire Plugin to execute tests. In terms of my test breakdown I have several classes, some of which have 1 test in there and some more than one test.

So on my Grid i have 30 chrome web drivers and I want to execute all tests within all classes in parallel.

I've read how to do this using the parallel parameter which i have set as:

            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.17</version>
                <configuration>
                    <includes>
                        <include>${testSuite}</include>
                    </includes>
                    <parallel>all</parallel>
                    <useSystemClassLoader>false</useSystemClassLoader>
                    <perCoreThreadCount>false</perCoreThreadCount>
                    <threadCount>20</threadCount>
                    <browser>${browser_type}</browser>
                </configuration>
            </plugin>

However this doesnt seem to fill all the Chrome web drivers I have available.

If i then use forkCount, like:

<forkCount>20</forkCount>
<reuseForks>true</reuseForks>

Then when the test execution first starts, all web drivers are filled however it quickly starts dropping and behaving one at a time.

So my questions:

• Is there a relationship between forkCount and threadCount
• Is there anything additional I need to do to really get this running in parallel?

Thanks.

Answer 1

You have to provide explicit junit test provider:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.18.1</version>
    <dependencies>
        <dependency>
            <groupId>org.apache.maven.surefire</groupId>
            <artifactId>surefire-junit47</artifactId>
            <version>2.18.1</version>
        </dependency>
    </dependencies>
    <configuration>
        <parallel>all</parallel>
        <useUnlimitedThreads>true</useUnlimitedThreads>
        <useSystemClassLoader>false</useSystemClassLoader>
        <includes>
            <include>${testSuite}</include>
        </includes>
        <systemPropertyVariables>
            <browser>${browser_type}</browser>
        </systemPropertyVariables>
     </configuration>
</plugin>

And you should use JUnit 4.7+ as older versions does not work with parallel testing correctly.

Also you can omit fork-related parameters if your tests do NOT affect JVM runtime (usually it's not the case).

Or migrate your tests to TestNG - it is more elegant framework and it works with parallel testing much better, then JUnit (imo).