Automated java module checking

[marcingrzejszczak]

I've added a task called testModules that essentially calls

$ java -p module-name/build/libs/module-name-1.10.0-SNAPSHOT.jar --list-modules

If the module system is broken this task will fail.

The motivation to add this check is to catch issues like the one found in #3398.

TODO:

• I failed to retrieve JAVA_HOME from Java Toolchain from Gradle
• Maybe there's something smarter to test this?
• Plug in testModules to the whole build

[jonatan-ivanov]

This is failing for me because:

Error occurred during initialization of boot layer
java.lang.module.FindException: Unable to derive module descriptor for /.../micrometer/implementations/micrometer-registry-new-relic/build/libs/micrometer-registry-new-relic-1.10.0-SNAPSHOT.jar
Caused by: java.lang.module.FindException: Automatic-Module-Name: micrometer.registry.new.relic: Invalid module name: 'new' is not a Java identifier

[jonatan-ivanov]

Also, this way, this is executed against the bom, the samples and the benchmarks too, I think this also fails since the bom does not have a jar.

I think it is an easy fix, we just need to put a few lines below, after this section:

jar {
    manifest.attributes.put('Automatic-Module-Name', project.name.replace('-', '.'))
    metaInf {
        from "$rootDir/LICENSE"
        from "$rootDir/NOTICE"
    }
}

[shakuzen]

I made a separate issue for the new relic automatic module name: #3412

[jonatan-ivanov]

This: libs${File.separator}/ will cause: libs// but I would not bother building the path like this, since the jar task has a archivePath property. Also, you can get the java executable path programmatically and we can add some error handling so that we see why the command failed:

task testModules(type: Exec) {
    dependsOn jar
    String executablePath = javaToolchains.launcherFor { languageVersion = javaLanguageVersion }.get().executablePath
    commandLine "$executablePath", '-p', "$jar.archivePath", '--list-modules'
    standardOutput = new ByteArrayOutputStream()
    ignoreExitValue = true

    doLast {
        if (execResult.getExitValue() != 0) {
            throw new GradleException("Command finished with non-zero exit value ${execResult.getExitValue()}:\n$standardOutput")
        }
    }
}