Add requirement that load_image sets a viewport

Author: mwcraig

src/astro_image_display_api/interface_definition.py

@@ -57,6 +57,13 @@ def load_image(self, data: Any, image_label: str | None = None) -> None:
         data : Any
             The data to load. This can be a FITS file, a 2D array,
             or an `astropy.nddata.NDData` object.
+
+        image_label : str, optional
+            The label for the image.
+
+        Notes
+        -----
+        Loading an image should also set the viewport for that image.
         """
         raise NotImplementedError
 

src/astro_image_display_api/widget_api_test.py

@@ -157,20 +157,30 @@ def test_set_get_viewport_errors(self, data, wcs):
         with pytest.raises(ValueError, match='[Ii]mage label.*not provided'):
             self.image.get_viewport()
 
-    def test_set_get_view_port_no_image_label(self, data):
-        # If there is only one image, the viewport should be able to be set
-        # and retrieved without an image label.
-
-        # Add an image without an image label
+    def test_viewport_is_defined_aster_loading_image(self, data):
+        # Check that the viewport is set to a default value when an image
+        # is loaded, even if no viewport is explicitly set.
         self.image.load_image(data)
 
         # Getting the viewport should not fail...
         vport = self.image.get_viewport()
+
         assert 'center' in vport
+        # No world, so center should be a tuple
+        assert isinstance(vport['center'], tuple)
         assert 'fov' in vport
+        # fov should be a float since no WCS
+        assert isinstance(vport['fov'], float)
         assert 'image_label' in vport
         assert vport['image_label'] is None
 
+    def test_set_get_view_port_no_image_label(self, data):
+        # If there is only one image, the viewport should be able to be set
+        # and retrieved without an image label.
+
+        # Add an image without an image label
+        self.image.load_image(data)
+
         # Set the viewport without an image label
         self.image.set_viewport(center=(10, 10), fov=100)