Make heartbeat unit tests a bit more robust.

test/unit/queue_worker/test_database_heartbeat.py

@@ -27,17 +27,38 @@ def test_database_heartbeat(heartbeat_app):
     active_processes = heartbeat_app.database_heartbeat.get_active_processes()
     assert len(active_processes) == 0
     heartbeat_app.database_heartbeat.start()
+
+    def one_active_process():
+        active_processes = heartbeat_app.database_heartbeat.get_active_processes()
+        assert len(active_processes) == 1
+        process = active_processes[0]
+        return process
+
     # thread needs to start
-    time.sleep(0.5)
-    active_processes = heartbeat_app.database_heartbeat.get_active_processes()
-    assert len(active_processes) == 1
-    process = active_processes[0]
+    process = wait_for_assertion(one_active_process)
     update_time = process.update_time
-    time.sleep(0.2)
-    heartbeat_app.model.context.refresh(process)
-    next_update_time = process.update_time
-    assert update_time < next_update_time
+
+    def process_updated():
+        heartbeat_app.model.context.refresh(process)
+        next_update_time = process.update_time
+        assert update_time < next_update_time
+
+    wait_for_assertion(process_updated)
+
     heartbeat_app.database_heartbeat.shutdown()
     time.sleep(0.5)
     assert len(heartbeat_app.database_heartbeat.get_active_processes(last_seen_seconds=5)) == 1
     assert len(heartbeat_app.database_heartbeat.get_active_processes(last_seen_seconds=0.4)) == 0
+
+
+def wait_for_assertion(assert_f):
+    assertion_error = None
+    for i in range(10):
+        try:
+            v = assert_f()
+            return v
+        except AssertionError as e:
+            assertion_error = e
+        time.sleep(.2)
+
+    raise assertion_error