Test Driven Detectors 4 FindBugs

Utility for test driving development of FindBugs plugins. Allows writing unit tests which run your custom detector against a given class, and assert on bugs, if any, reported by the detector.

Installation

Add test-driven-detectors4findbugs as a dependency for use in unit tests. The dependency can be downloaded directly, or listed in Maven-compatible build tools with the following information:

groupId	artifactId	version	scope
com.youdevise	test-driven-detectors4findbugs	1.0	test

(it may take a little while to sync to Maven Central, revert to version 0.2.1 if necessary)

test-driven-detectors4findbugs depends on Hamcrest 1.1+, and FindBugs 1.3.9 to 2.0.2. Custom detectors developed against 1.3.9 will work with 2.0+ versions of FindBugs, despite differences in the detector API.

How To Use

An example would best illustrate how to use test your custom detectors.

Consider that you want to write a FindBugs plugin which will report a bug against classes whose type names are too long (not that you'd want to do that, of course).

Start with two code examples (or 'benchmarks'), one which you wish to report a bug for, and one which would you don't.

E.g:

public class ExampleClassWithAnAllowedName {

}

public class ExampleClassWithANameThatIsTooLongForThisSillyDetector {

}

Next write the template for your custom FindBugs detector:

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.ba.ClassContext;

public class CustomClassNameLengthDetector implements Detector {
	
	private final BugReporter bugReporter;

    // Every custom detector requires a constructor with this signature.
	public CustomClassNameLengthDetector(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
	}
	
	@Override public void report() { }

	@Override public void visitClassContext(ClassContext classContext) { }

}

Now write a failing test to develop against:

import static com.youdevise.fbplugins.tdd4fb.DetectorAssert.ofType;
import com.youdevise.fbplugins.tdd4fb.DetectorAssert;

import org.junit.Test;

import edu.umd.cs.findbugs.BugReporter;

public class CustomClassNameLengthDetectorTest {

	@Test public void
	raisesAnyBugAgainstClassWithLongName() throws Exception {
	
	    // Must obtain a BugReporter instance from this method
		BugReporter bugReporter = DetectorAssert.bugReporterForTesting();
		
		// And pass the same BugReporter to your detector
		CustomClassNameLengthDetector detector = new CustomClassNameLengthDetector(bugReporter);
		
		// Next assert that your detector has raised a bug against a specific class
		DetectorAssert.assertBugReported(ExampleClassWithANameThatIsTooLongForThisSillyDetector.class, 
										 detector, 
										 bugReporter);
	}
}

Since the detector never reports a bug, this predictably fails. You can now begin to develop your custom detector with the tight feedback loop of test-driven development!

All assertion methods, and other functionality is accessed through the static methods of DetectorAssert.

Building from source

The project can be built with Maven.

Run 'mvn package' to build the JAR.

License

Open source under the very permissive MIT license. Copyright 2010 TIM Group.

Acknowledgements

A project of youDevise.