BUG: Fix bug in tests for fairlearn + 1 more test (#313)

We merged #298 and #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.

To be clear, the only change needed to fix the tests is the following:

```python
- actual_table = card.select("Metric Frame Table").content.format()
+ actual_table = card.select("Metric Frame Table").format()
```

On top, I added the `description` argument to `add_fairlearn_metric_frame`, to be consistent with all the other methods (also changed in #310), and I also added as a test for it. Since we now have 2 tests, I moved the `metric_frame` variable to a fixture.

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