test results of ForumSharingIntegrationTest depend on test execution order

I came across this by chance, but the changes (diff below) make the problem reproducible.

Steps to reproduce:

Running testInviteeLeavesAfterFinished before testSharerLeavesAfterFinished will lead to the following test failure:

java.lang.AssertionError: expected:<1> but was:<0>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:834)
	at org.junit.Assert.assertEquals(Assert.java:645)
	at org.junit.Assert.assertEquals(Assert.java:631)
	at org.briarproject.briar.sharing.ForumSharingIntegrationTest.testSharerLeavesBeforeResponse(ForumSharingIntegrationTest.java:396)
...

(just one example, there are more test orders to reproduce this)

code to reproduce:

index 987a78d20..2b042455f 100644
--- a/briar-core/src/test/java/org/briarproject/briar/sharing/ForumSharingIntegrationTest.java
+++ b/briar-core/src/test/java/org/briarproject/briar/sharing/ForumSharingIntegrationTest.java
@@ -43,6 +43,8 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import org.junit.FixMethodOrder;
+import org.junit.runners.MethodSorters;@FixMethodOrder(MethodSorters.NAME_ASCENDING)
 public class ForumSharingIntegrationTest
                extends BriarIntegrationTest<BriarIntegrationTestComponent> {
 
@@ -235,7 +237,7 @@ public class ForumSharingIntegrationTest
        }
 
        @Test
-       public void testInviteeLeavesAfterFinished() throws Exception {
+       public void test1InviteeLeavesAfterFinished() throws Exception {
                // initialize and let invitee accept all requests
                listenToEvents(true);
 
@@ -292,7 +294,7 @@ public class ForumSharingIntegrationTest
        }
 
        @Test
-       public void testSharerLeavesAfterFinished() throws Exception {
+       public void test2SharerLeavesAfterFinished() throws Exception {
                // initialize and let invitee accept all requests
                listenToEvents(true);

Suggestion: prepare each test in ForumSharingIntegrationTest without relying on any state created by other tests.