Make figure directly accesable through CodeExercise

If one output is only given that is translated to a `CueFigure` then it
can be accessed with `code_exercise.figure` instead of
`code_exercise.output.figure`

src/scwidgets/exercise/_widget_code_exercise.py

@@ -687,6 +687,15 @@ def output(self) -> CueOutput | None:
     def outputs(self) -> List[CueOutput]:
         return self._cue_outputs
 
+    @property
+    def figure(self) -> Figure | None:
+        return (
+            self._cue_outputs[0].figure
+            if len(self._cue_outputs) > 0
+            and isinstance(self._cue_outputs[0], CueFigure)
+            else None
+        )
+
     def _on_click_update_action(self) -> bool:
         self._output.clear_output(wait=True)
         raised_error = False

tests/test_code.py

@@ -1,9 +1,11 @@
 import os
 from typing import Callable, List, Literal, Union
 
+import matplotlib.pyplot as plt
 import numpy as np
 import pytest
 from ipywidgets import fixed
+from matplotlib.figure import Figure
 from widget_code_input.utils import CodeValidationError
 
 from scwidgets.check import Check, CheckRegistry, CheckResult
@@ -345,3 +347,11 @@ def failing_update(a, b):
                 code=TestCodeInput.mock_function_0,
                 update_func=failing_update,
             )
+
+    def test_figure(self):
+        """Test figure"""
+
+        code_ex = CodeExercise(outputs=plt.figure())
+        assert isinstance(code_ex.figure, Figure)
+        assert code_ex.output.figure is code_ex.figure
+        assert code_ex.outputs[0] is code_ex.output