fix(gridgen): only add suffix for generated shpfiles

flopy/utils/gridgen.py

@@ -406,7 +406,7 @@ def add_refinement_features(self, features, featuretype, level, layers):
         """
         Parameters
         ----------
-        features : str, list, or collection object
+        features : str or list, or collection object
             features can be
                 a string containing the name of a shapefile
                 a list of points, lines, or polygons
@@ -435,15 +435,17 @@ def add_refinement_features(self, features, featuretype, level, layers):
 
         # Create shapefile or set shapefile to feature
         rfname = f"rf{len(self._rfdict)}"
-        if isinstance(features, list):
+        if isinstance(features, (str, os.PathLike)):
+            shapefile = features
+        elif isinstance(features, (list, tuple, np.ndarray)):
             rfname_w_path = os.path.join(self.model_ws, rfname)
             features_to_shapefile(features, featuretype, rfname_w_path)
-            shapefile = rfname
+            shapefile = f"{rfname}.shp"
         else:
-            shapefile = features
+            raise ValueError(f"Features must be path-like or array-like")
 
         self._rfdict[rfname] = [shapefile, featuretype, level]
-        sn = os.path.join(self.model_ws, f"{shapefile}.shp")
+        sn = os.path.join(self.model_ws, shapefile)
         assert os.path.isfile(sn), f"Shapefile does not exist: {sn}"
 
         for k in layers: