Make BrambleTestCase fail if background thread throws an exception

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

@@ -1,17 +1,34 @@
 package org.briarproject.bramble.test;
 
+import org.junit.After;
+import org.junit.Before;
+
 import java.lang.Thread.UncaughtExceptionHandler;
 
 import static org.junit.Assert.fail;
 
 public abstract class BrambleTestCase {
 
+	private volatile boolean exceptionInBackgroundThread = false;
+
 	public BrambleTestCase() {
 		// Ensure exceptions thrown on worker threads cause tests to fail
 		UncaughtExceptionHandler fail = (thread, throwable) -> {
 			throwable.printStackTrace();
-			fail();
+			exceptionInBackgroundThread = true;
 		};
 		Thread.setDefaultUncaughtExceptionHandler(fail);
 	}
+
+	@Before
+	public void before() {
+		exceptionInBackgroundThread = false;
+	}
+
+	@After
+	public void after() {
+		if (exceptionInBackgroundThread) {
+			fail("background thread has thrown an exception");
+		}
+	}
 }

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

@@ -12,7 +12,7 @@ public class ThreadExceptionTest extends BrambleTestCase {
 		fail();
 	}
 
-	@Test(expected = AssertionError.class)
+	@Test
 	public void testExceptionInThreadMakesTestCaseFail() {
 		Thread t = new Thread(() -> {
 			System.out.println("thread before exception");
@@ -24,7 +24,8 @@ public class ThreadExceptionTest extends BrambleTestCase {
 			t.join();
 			System.out.println("joined thread");
 		} catch (InterruptedException e) {
-			e.printStackTrace();
+			System.out.println("interrupted while joining thread");
+			fail();
 		}
 	}