In my maven project, I have added testng with test scope.

    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>7.1.0</version>
        <scope>test</scope>
    </dependency> 

I observed that class files from the guava version which testng depends on has ended up in my fat jar (I build the fat jar with maven-assembly-plugin).

Guava is not added directly as a dependency to my project, instead it is depended by protobuf-java-util dependency which I have added in my project. What I have observed is that the guava class files included in the fat jar are from the guava version depended by testng instead of the version depended by protobuf-java-util

When I excluded guava from testng, I can observe that the correct version of guava is picked up transitively from protobuf-java-util.

    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>7.1.0</version>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>com.google.guava</groupId>
                <artifactId>guava</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

Note that the module I am observing this is a nested sub module two levels deep from the root pom, and the testng dependency is in the root pom. I also observed that if I change the place which protobuf-java-util dependency is added, it gets precedence over the version derived from testng.

I also observed the same in the mvn:dependency-tree output, where guava is not shown under protobuf-java-util but under testng (with test scope), and when I added the exclusion above, it is correctly shown under protobuf-java-util.

What is the reason for this? From what I understood reading the documentation, the test scoped dependencies are only for test execution, so I wouldn’t expect them to see in my fat jar.