Only allow big-image if image is specified

pyxform/survey_element.py

@@ -428,10 +428,15 @@ def xml_label_and_hint(self) -> "List[DetachableElement]":
         msg = "The survey element named '%s' " "has no label or hint." % self.name
         if len(result) == 0:
             raise PyXFormError(msg)
+
         # Guidance hint alone is not OK since they may be hidden by default.
         if not any((self.label, self.media, self.hint)) and self.guidance_hint:
             raise PyXFormError(msg)
 
+        # big-image must combine with image
+        if not ("image" in self.media) and "big-image" in self.media:
+            raise PyXFormError("You must specify an image in order to use big-image.")
+
         return result
 
     def xml_bindings(self):

tests/test_sheet_columns.py

@@ -29,7 +29,7 @@ def test_missing_name_but_has_alias_of_name(self):
             errored=False,
         )
 
-    def test_missing_label(self):
+    def test_label_or_hint__must_be_provided(self):
         self.assertPyxformXform(
             name="invalidcols",
             ss_structure={"survey": [{"type": "text", "name": "q1"}]},
@@ -63,6 +63,18 @@ def test_label_node_added_when_hint_given_but_no_label_value(self):
             xml__contains=prep_for_xml_contains(expected),
         )
 
+    def test_big_image_invalid_if_no_image(self):
+        self.assertPyxformXform(
+            name="data",
+            md="""
+            | survey |      |      |                  |
+            |        | type | name | media::big-image |
+            |        | text | c    | m.png            |
+            """,
+            errored=True,
+            error__contains=["must specify an image"],
+        )
+
     def test_column_case(self):
         """
         Ensure that column name is case insensitive