PYTHON-2447 Fix race in CMAP maxConnecting test (#529)

Author: ShaneHarvey

test/cmap/pool-checkout-maxConnecting-is-enforced.json

@@ -30,32 +30,31 @@
       "name": "start",
       "target": "thread1"
     },
-    {
-      "name": "checkOut",
-      "thread": "thread1"
-    },
     {
       "name": "start",
       "target": "thread2"
     },
     {
-      "name": "wait",
-      "thread": "thread2",
-      "ms": 100
+      "name": "start",
+      "target": "thread3"
     },
     {
       "name": "checkOut",
-      "thread": "thread2"
+      "thread": "thread1"
     },
     {
-      "name": "start",
-      "target": "thread3"
+      "name": "waitForEvent",
+      "event": "ConnectionCreated",
+      "count": 1
     },
     {
       "name": "wait",
-      "thread": "thread3",
       "ms": 100
     },
+    {
+      "name": "checkOut",
+      "thread": "thread2"
+    },
     {
       "name": "checkOut",
       "thread": "thread3"

test/test_cmap.py

@@ -172,6 +172,8 @@ def check_events(self, events, ignore):
         """Check the events of a test."""
         actual_events = self.actual_events(ignore)
         for actual, expected in zip(actual_events, events):
+            self.logs.append('Checking event actual: %r vs expected: %r' % (
+                actual, expected))
             self.check_event(actual, expected)
 
         if len(events) > len(actual_events):
@@ -196,6 +198,7 @@ def set_fail_point(self, command_args):
 
     def run_scenario(self, scenario_def, test):
         """Run a CMAP spec test."""
+        self.logs = []
         self.assertEqual(scenario_def['version'], 1)
         self.assertIn(scenario_def['style'], ['unit', 'integration'])
         self.listener = CMAPListener()
@@ -240,8 +243,7 @@ def cleanup():
             self.check_events(test['events'], test['ignore'])
         except Exception:
             # Print the events after a test failure.
-            print()
-            print('Failed test: %r' % (test['description'],))
+            print('\nFailed test: %r' % (test['description'],))
             print('Operations:')
             for op in self._ops:
                 print(op)
@@ -252,6 +254,9 @@ def cleanup():
             print('Events:')
             for event in self.listener.events:
                 print(event)
+            print('Log:')
+            for log in self.logs:
+                print(log)
             raise
 
     POOL_OPTIONS = {