Merge pull request #457 from gushil/fix-452-trigger-ref-hidden-question

Triggers referring to hidden question will produce an error.

pyxform/question.py

@@ -32,6 +32,16 @@ def xml_instance(self, **kwargs):
 
     def xml_control(self):
         if ("calculate" in self.bind or self.trigger) and not (self.label or self.hint):
+            nested_setvalues = self.get_root().get_setvalues_for_question_name(
+                self.name
+            )
+            if nested_setvalues:
+                for setvalue in nested_setvalues:
+                    msg = (
+                        "Trigger was added for ${%s} that refers to hidden question. This is not allowed."
+                        % setvalue[0]
+                    )
+                    raise PyXFormError(msg)
             return None
 
         xml_node = self.build_xml()

pyxform/tests_v1/test_trigger.py

@@ -158,6 +158,22 @@ def test_handling_trigger_column_with_no_calculation_no_label_no_hint(self):
             ],
         )
 
+    def test_trigger_refer_to_hidden_node_ref_gives_error(self):
+        self.assertPyxformXform(
+            name="trigger-invalid-ref",
+            md="""
+            | survey |           |        |                      |         |             |
+            |        | type      | name   | label                | trigger | calculation |
+            |        | calculate | one    |                      |         | 5 + 4       |
+            |        | calculate | one-ts |                      | ${one}  | now()       |
+            |        | note      | note   | timestamp: ${one-ts} |         |             |
+            """,
+            errored=True,
+            error__contains=[
+                "Trigger was added for ${one-ts} that refers to hidden question. This is not allowed."
+            ],
+        )
+
     def test_handling_trigger_column_in_group(self):
         md = """
         | survey |             |      |                    |             |         |