Allow BrambleTestCase to handle background thread exceptions gracefully during after()

bramble-api/src/test/java/org/briarproject/bramble/test/BrambleTestCase.java

@@ -4,31 +4,37 @@ import org.junit.After;
 import org.junit.Before;
 
 import java.lang.Thread.UncaughtExceptionHandler;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
+import static java.util.logging.Logger.getLogger;
 import static org.junit.Assert.fail;
 
 public abstract class BrambleTestCase {
 
-	private volatile boolean exceptionInBackgroundThread = false;
+	private static final Logger LOG =
+			getLogger(BrambleTestCase.class.getName());
+
+	protected volatile boolean exceptionInBackgroundThread = false;
 
 	public BrambleTestCase() {
 		// Ensure exceptions thrown on worker threads cause tests to fail
 		UncaughtExceptionHandler fail = (thread, throwable) -> {
-			throwable.printStackTrace();
+			LOG.log(Level.WARNING, "Caught unhandled exception", throwable);
 			exceptionInBackgroundThread = true;
 		};
 		Thread.setDefaultUncaughtExceptionHandler(fail);
 	}
 
 	@Before
-	public void before() {
+	public void beforeBrambleTestCase() {
 		exceptionInBackgroundThread = false;
 	}
 
 	@After
-	public void after() {
+	public void afterBrambleTestCase() {
 		if (exceptionInBackgroundThread) {
-			fail("background thread has thrown an exception");
+			fail("background thread has thrown an exception unexpectedly");
 		}
 	}
 }

bramble-api/src/test/java/org/briarproject/bramble/test/ThreadExceptionTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.test;
 
+import org.junit.Assert;
 import org.junit.Test;
 
 import static org.junit.Assert.fail;
@@ -27,7 +28,9 @@ public class ThreadExceptionTest extends BrambleTestCase {
 			System.out.println("interrupted while joining thread");
 			fail();
 		}
+
+		Assert.assertTrue(exceptionInBackgroundThread);
+		exceptionInBackgroundThread = false;
 	}
 
-
 }