Fix bug in tests for fairlearn + 1 more test

We merged skops-dev#298 and skops-dev#310 shortly after each other but they contained an
incompatibility that broke the fairlearn tests (the code itself was
fine). This PR fixes this incompatibility.

On top, I added the description argument to add_fairlearn_metric_frame,
to be consistent with all the other methods, and also as a test for it.

Finally, 2 small fixes:

- Added type annotation to transpose argument
- Changed order of arguments in docstring to match order in signature

skops/card/_model_card.py

@@ -1236,7 +1236,8 @@ def add_fairlearn_metric_frame(
         self,
         metric_frame,
         table_name: str = "Fairlearn MetricFrame Table",
-        transpose=True,
+        transpose: bool = True,
+        description: str | None = None,
     ) -> Self:
         """
         Add a :class:`fairlearn.metrics.MetricFrame` table to the model card. The table contains
@@ -1247,11 +1248,15 @@ def add_fairlearn_metric_frame(
         metric_frame: MetricFrame
             The Fairlearn MetricFrame to add to the model card.
 
+        table_name: str
+            The desired name of the table section in the model card.
+
         transpose: bool, default=True
             Whether to transpose the table or not.
 
-        table_name: str
-            The desired name of the table section in the model card.
+
+        description : str | None (default=None)
+            An optional description to be added before the table.
 
         Returns
         -------
@@ -1277,7 +1282,9 @@ def add_fairlearn_metric_frame(
 
             frame_dict = pd.DataFrame(frame_dict).T
 
-        return self.add_table(folded=True, **{table_name: frame_dict})
+        return self.add_table(
+            folded=True, description=description, **{table_name: frame_dict}
+        )
 
     def _add_metrics(
         self,

skops/card/tests/test_card.py

@@ -1721,8 +1721,8 @@ def card(self):
         card = Card(model=model)
         return card
 
-    @pytest.mark.parametrize("transpose", [True, False])
-    def test_metric_table(self, card: Card, transpose):
+    @pytest.fixture
+    def metric_frame(self):
         metrics = import_or_raise(
             "fairlearn.metrics", "model card fairlearn metricframe"
         )
@@ -1734,13 +1734,17 @@ def test_metric_table(self, card: Card, transpose):
         metric_frame = metrics.MetricFrame(
             y_true=y_true, y_pred=y_pred, sensitive_features=sex, metrics=metric_dict
         )
+        return metric_frame
+
+    @pytest.mark.parametrize("transpose", [True, False])
+    def test_metric_table(self, card: Card, transpose, metric_frame):
         card.add_fairlearn_metric_frame(
             metric_frame=metric_frame,
             transpose=transpose,
             table_name="Metric Frame Table",
         )
 
-        actual_table = card.select("Metric Frame Table").content.format()
+        actual_table = card.select("Metric Frame Table").format()
 
         if transpose is True:
             expected_table = (
@@ -1757,3 +1761,19 @@ def test_metric_table(self, card: Card, transpose):
             )
 
         assert expected_table == actual_table
+
+    def test_metric_table_with_description(self, card: Card, metric_frame):
+        card.add_fairlearn_metric_frame(
+            description="An awesome table",
+            metric_frame=metric_frame,
+            table_name="Metric Frame Table",
+        )
+
+        actual_table = card.select("Metric Frame Table").format()
+        expected_table = (
+            "An awesome table\n\n"
+            "<details>\n<summary> Click to expand </summary>\n\n|   selection_rate"
+            " |\n|------------------|\n|              0.4 |\n|              0.8"
+            " |\n|              0.4 |\n|              0.5 |\n\n</details>"
+        )
+        assert expected_table == actual_table