deprecate get_fileext (#363)

changes/363.removal.rst

@@ -0,0 +1 @@
+Deprecate DataModel.get_fileext.

src/stdatamodels/model_base.py

@@ -1001,6 +1001,10 @@ def schema(self):
         return self._schema
 
     def get_fileext(self):
+        warnings.warn(
+            "get_fileext always returns 'fits' and will be removed in an upcoming release",
+            DeprecationWarning
+        )
         return 'fits'
 
     @property

tests/test_models.py

@@ -326,3 +326,9 @@ def find_gen_by_id(object_id):
             # many models which would indicate they are difficult to garbage
             # collect.
             assert len(mids) < 2
+
+
+def test_get_fileext_deprecation():
+    m = DataModel()
+    with pytest.warns(DeprecationWarning):
+        assert m.get_fileext() == 'fits'