The gdbusproxy async test creates a proxy asynchronously and then immediately returns. The test framework then takes down the connection, so the async test's callback may never be called. If it is called, it can fail because it expects no error, while an error is set because the connection has since been closed by the test framework. If I modify the test to start a main loop, it then fails because some of the property tests fail because a previous test modified the value of the properties. I talked with davidz on irc, and he feels that the test is broken because it relies on the gdbusproxy test setting up the server, and tests should be able to run in any order and independently of other tests.