fix: Raise an error when CrossValidationReport fails before at least one estimator is fitted

skore/src/skore/sklearn/_cross_validation/report.py

@@ -213,6 +213,11 @@ def _fit_estimator_reports(self) -> list[EstimatorReport]:
                     "might not contain all the expected results. "
                     f"Traceback: \n{e}"
                 )
+            if len(estimator_reports) == 0:
+                raise RuntimeError(
+                    "Cross-validation failed: no estimators were successfully fitted. "
+                    "Please check your data, estimator, or cross-validation setup."
+                ) from e
 
             console.print(
                 Panel(
@@ -222,7 +227,6 @@ def _fit_estimator_reports(self) -> list[EstimatorReport]:
                     border_style="cyan",
                 )
             )
-
         return estimator_reports
 
     def clear_cache(self) -> None:

skore/tests/unit/sklearn/test_cross_validation.py

@@ -988,3 +988,19 @@ def test_cross_validation_timings(
         "Predict time test",
     ]
     assert timings.columns.tolist() == expected_columns
+
+
+class BrokenEstimator(ClassifierMixin, BaseEstimator):
+    def fit(self, X, y):
+        raise ValueError("Intentional failure for testing")
+
+    def predict(self, X):
+        return [0] * len(X)
+
+
+def test_cross_validation_report_with_zero_estimators():
+    X, y = make_classification(n_samples=100, n_features=10, random_state=42)
+
+    err_msg = "Cross-validation failed: no estimators were successfully fitted"
+    with pytest.raises(RuntimeError, match=err_msg):
+        CrossValidationReport(BrokenEstimator(), X, y)