Clarify equal opportunity warning message

sklego/metrics.py

@@ -166,14 +166,16 @@ def impl(estimator, X, y_true):
         # fair so we return 0
         if len(y_given_z1_y1) == 0:
             warn(
-                f"No samples with y_hat == {positive_target} for {sensitive_column} == 1, returning 0",
+                f"No samples with y_true == {positive_target} and y_hat == {positive_target} "
+                f"for {sensitive_column} == 1, returning 0",
                 RuntimeWarning,
             )
             return 0
 
         if len(y_given_z0_y1) == 0:
             warn(
-                f"No samples with y_hat == {positive_target} for {sensitive_column} == 0, returning 0",
+                f"No samples with y_true == {positive_target} and y_hat == {positive_target} "
+                f"for {sensitive_column} == 0, returning 0",
                 RuntimeWarning,
             )
             return 0

tests/test_metrics/test_equal_opportunity.py

@@ -81,3 +81,4 @@ def test_warning_is_logged(sensitive_classification_dataset):
         # Trigger a warning.
         equal_opportunity_score("x2", positive_target=2)(mod_fair, X, y)
         assert issubclass(w[-1].category, RuntimeWarning)
+        assert "y_true == 2 and y_hat == 2" in str(w[-1].message)