Adding QueueBoundedDatabase test

Author: apetenchea

tests/test_queue_bounded.py

@@ -0,0 +1,43 @@
+import warnings
+
+from arango.exceptions import QueueBoundedExecutorError
+
+
+def flood_with_requests(bounded_db, async_db):
+    """
+    Flood the database with requests.
+    It is impossible to predict what the last recorded queue time will be.
+    We can only try and make it as large as possible. However, if the system
+    is fast enough, it may still be 0.
+    """
+    for _ in range(3):
+        for _ in range(500):
+            async_db.aql.execute("RETURN SLEEP(0.5)", count=True)
+        for _ in range(3):
+            bounded_db.aql.execute("RETURN SLEEP(0.5)", count=True)
+        if bounded_db.last_queue_time >= 0:
+            break
+
+
+def test_queue_bounded(db):
+    bounded_db = db.begin_queue_bounded_execution(100)
+    async_db = db.begin_async_execution(return_result=True)
+
+    flood_with_requests(bounded_db, async_db)
+    assert bounded_db.last_queue_time >= 0
+
+    # We can only emit a warning here. The test will still pass.
+    if bounded_db.last_queue_time == 0:
+        warnings.warn("last_queue_time is 0, test may be unreliable")
+
+    bounded_db.adjust_max_queue_time(0.0001)
+    try:
+        flood_with_requests(bounded_db, async_db)
+        assert bounded_db.last_queue_time >= 0
+    except QueueBoundedExecutorError as e:
+        assert e.http_code == 412
+        assert e.error_code == 21004
+    else:
+        warnings.warn(
+            f"last queue time is {bounded_db.last_queue_time}, test may be unreliable"
+        )