Running JUnitCore with instances instead of classes

Question

I'm looking to run JUnit 4.12+ programmatically, and a cursory search for doing so yielded (amongst many other similar posts) this answer, which prescribes the following basic solution:

@RunWith(Suite)
@Suite.SuiteClasses ({
    MyTestClass1.class,
    MyTestClass2.class
})
public class MyTestSuite {
}

Result testResults = JUnitCore.runClasses(MyTestSuite.class);

...and I was able to get this working, no sweat. So far so good!

Problem is: I have some pretty sophisticated test classes that need to be instantiated/injected with very specific properties at runtime...not something that can be done from inside a no-arg constructor. But the above method (specifying to just run any old instance of a set of classes) doesn't allow you to instantiate your test classes, configure them, and then run them.

Is there a way to do this? I couldn't find anything looking at the JUnit API. I am looking for something like:

MyTestClass1 mtc1 = new MyTestClass1(...);
MyTestClass2 mtc2 = new MyTestClass2(...);
Result testResults = JUnitCore.run(mtc1, mtc2);

Answer 1

I got this working with a custom Runner with sample (Groovy pseudo-code) as follows:

class MyRunner extends Runner {
    @Override
    Description getDescription() {
        return null
    }

    @Override
    void run(RunNotifier notifier) {
        // LoginTests.class is a test class I want to run
        LoginTests loginTests = new LoginTests(<my args here>)

        Description description = Description.createSuiteDescription(LoginTests)
        notifier.fireTestStarted(description)
        try {
            log.info("About to doSomething()...")
            loginTests.doSomething()
            log.info("Did it...")
            notifier.fireTestFinished(description)
        } catch(Throwable throwable) {
            log.info("doSomething() failed...")
            notifier.fireTestAssumptionFailed(new Failure(description, throwable))
        }
    }
}

Result testResults = new JUnitCore().run(Request.runner(new MyRunner()))