Maven won't run tests from parent or child projects

Question

I got a multi-module project. Each project has its own unittest same for the parent project. When I use mvn test no tests are run and the target folder does not contain any test classes. Parent project doesn't even create a target folder

Structure looks like this:

|-module1-> pom.xml
|-module2-> pom.xml
|-module3-> pom.xml
|-src/main
|-src/test/java/MyTest.java
|-pom.xml

See poms below ( I omited standard pom boilerplate)

parent pom.xml

<groupId>com.tests</groupId>
<artifactId>unit-tests</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>

<modules>
    <module>module1</module>
    <module>module2</module>
    <module>module3</module>
</modules>

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <scope>test</scope>
        <version>RELEASE</version>
    </dependency>
<dependencies>

Child pom has:

<parent>
    <groupId>com.tests</groupId>
    <artifactId>unit-tests</artifactId>
    <version>1.0-SNAPSHOT</version>
</parent>

Whenever i run mvn clean test no tests are run and in the console i get something like:

[INFO] ------------------------------------------------------------------------
[INFO] Building unit-tests 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] ------------------------------------------------------------------------

Btw, parent project does not have any source code, just tests

Answer 1

You're using packaging pom. With that kind of packaging you're only allowed to run a small number of goals bound to phases (like install and deploy). In order to run the tests in the parent you must be explicit about your intentions, like this:

$mvn clean compiler:testCompile surefire:test

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.tests.unit_tests.TestModules
Test1!
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.016 s <<< FAILURE! - in com.tests.unit_tests.TestModules
[ERROR] test1(com.tests.unit_tests.TestModules)  Time elapsed: 0.003 s  <<< FAILURE!
java.lang.AssertionError
    at com.tests.unit_tests.TestModules.test1(TestModules.java:11)

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   TestModules.test1:11
[INFO] 
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] unit-tests ......................................... FAILURE [  1.262 s]
[INFO] module1 ............................................ SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.473 s
[INFO] Finished at: 2017-12-02T11:04:50-02:00
[INFO] Final Memory: 16M/207M
[INFO] ------------------------------------------------------------------------

That way you are telling maven that you want to compile (generate your target) and run your tests in the aggregator (which has the parent pom). Otherwise maven will only run the tests in the modules.

$mvn test

[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] unit-tests
[INFO] module1
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building unit-tests 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building module1 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ module1 ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 0 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.2:compile (default-compile) @ module1 ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ module1 ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 0 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.2:testCompile (default-testCompile) @ module1 ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-surefire-plugin:2.17:test (default-test) @ module1 ---
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] unit-tests ......................................... SUCCESS [  0.002 s]
[INFO] module1 ............................................ SUCCESS [  0.424 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.504 s
[INFO] Finished at: 2017-12-02T11:06:24-02:00
[INFO] Final Memory: 9M/241M
[INFO] ------------------------------------------------------------------------

I know that it is a hard reading, but you should check it out: http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html#Packaging

For example, a project that is purely metadata (packaging value is pom) only binds goals to the install and deploy phases (for a complete list of goal-to-build-phase bindings of some of the packaging types, refer to the Lifecycle Reference).

EDIT

As eis pointed out. Even though it's possible to do it, maven made it hard to do it because you SHOULDN't do it by default. Your unit tests should be in the module they are testing. It's not a good practice to scatter them.

The answer is: you can do it, yes. But you shouldn't! There are somethings in life that you can do, but shouldn't...

If we were talking about integration tests that would be a different story.. That's a different discussion.

Cheers!

Answer 2

multimodule parent has the packaging pom, and as such, can by definition only contain the pom, not any source code (not even test source code!). This is the reason your tests won't run and you don't get a target folder: there cannot be anything to run or compile on a project of type pom. A multimodule parent is only meant to group the modules together.

Answer 3

The maven surefire plugin runs all JUnit Test where the name of the testclass ends with Test - with a capital 'T'. According to your info your test class is named Mytest. Refactor that class to be named MyTest will make it work.