Use min trials, not arbitrary 0 (#2148)

Summary:
Pull Request resolved: #2148

I think this must have been a mistake

Reviewed By: esantorella

Differential Revision: D52847552

fbshipit-source-id: 3da6dbd2d45128f0bd5d748f10295c86991e7a84

ax/global_stopping/strategies/base.py

@@ -77,8 +77,12 @@ def should_stop_optimization(
             message = "There are pending trials in the experiment."
             return False, message
 
-        if len(experiment.trials_by_status[TrialStatus.COMPLETED]) == 0:
-            message = "There are no completed trials yet."
+        num_completed_trials = len(experiment.trials_by_status[TrialStatus.COMPLETED])
+        if num_completed_trials < self.min_trials:
+            message = (
+                f"There are only {num_completed_trials} completed trials, "
+                f"but {self} has a minumum of {self.min_trials}."
+            )
             return False, message
 
         return self._should_stop_optimization(experiment, **kwargs)

ax/global_stopping/tests/tests_strategies.py

@@ -51,7 +51,7 @@ def test_base_cases(self) -> None:
         self.assertFalse(stop)
         self.assertEqual(
             message,
-            "There are no completed trials yet.",
+            f"There are only 0 completed trials, but {gss_2} has a minumum of 2.",
         )
 
         # Insufficient trials to stop.
@@ -60,8 +60,7 @@ def test_base_cases(self) -> None:
         self.assertFalse(stop)
         self.assertEqual(
             message,
-            "There are not enough completed trials to "
-            "make a stopping decision (completed: 1, required: 3).",
+            f"There are only 1 completed trials, but {gss} has a minumum of 2.",
         )
 
         # Check that we properly count completed trials.
@@ -358,7 +357,7 @@ def test_safety_check(self) -> None:
         self.assertFalse(stop)
         self.assertEqual(
             message,
-            "There are no completed trials yet.",
+            f"There are only 0 completed trials, but {gss} has a minumum of 2.",
         )
 
     def test_constraint_satisfaction(self) -> None: