update tests for added methods

Author: eteq

src/astro_image_display_api/api_test.py

@@ -797,3 +797,24 @@ def test_save_overwrite(self, tmp_path):
 
         # Using overwrite should save successfully
         self.image.save(filename, overwrite=True)
+
+    def test_get_image_labels(self, data):
+        # the test viewer begins with a default empty image
+        assert len(self.image.get_image_labels()) == 1
+        assert self.image.get_image_labels()[0] == None
+        assert isinstance(self.image.get_image_labels(), tuple)
+
+        self.image.load_image(data, image_label="test")
+        assert len(self.image.get_image_labels()) == 2
+        assert self.image.get_image_labels()[-1] == 'test'
+
+    def test_get_image(self, data):
+        self.image.load_image(data, image_label="test")
+
+        # currently the type is not specified in the API
+        assert self.image.get_image() is not None
+        assert self.image.get_image(image_label="test") is not None
+        
+        with pytest.raises(ValueError, match="[Ii]mage label.*not found"):
+            self.image.get_image(image_label="not a valid label")
+

src/astro_image_display_api/image_viewer_logic.py

@@ -332,6 +332,18 @@ def load_image(
         # working with the new image.
         self._wcs = self._images[image_label].wcs
 
+
+    def get_image(self, image_label: str | None = None):
+        image_label = self._resolve_image_label(image_label)
+        if image_label not in self._images:
+            raise ValueError(
+                f"Image label '{image_label}' not found. Please load an image first."
+            )
+        return self._images[image_label]
+    
+    def get_image_labels(self):
+        return tuple(self._images.keys())
+
     def _determine_largest_dimension(self, shape: tuple[int, int]) -> int:
         """
         Determine which index is the largest dimension.

src/astro_image_display_api/interface_definition.py

@@ -80,13 +80,13 @@ def get_image(
     @abstractmethod
     def get_image_labels(
         self,
-    ) -> list[str]: 
+    ) -> tuple[str]: 
         """
         Get the labels of the loaded images.
 
         Returns
         -------
-        image_labels: list of str
+        image_labels: tuple of str
             The labels of the loaded images.
         """
         raise NotImplementedError