Better error message when users use THIS_MODULE in cases= instead of module=.

Author: Sylvain MARIE

docs/changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+### 1.11.3 IN PROGRESS - minor improvements
+
+Better error message when users use `THIS_MODULE` in `cases=` instead of `module=`.
+
 ### 1.11.2 - Increased tolerance to other plugins + bugfix
 
 Now when other plugins try to manipulate the fixture closure, warning messages are emitted but no error is raised. Fixed [#55](https://github.com/smarie/python-pytest-cases/issues/55).

pytest_cases/main_params.py

@@ -269,6 +269,8 @@ def get_all_cases(cases=None,               # type: Union[Callable[[Any], Any],
         if callable(cases):
             # single element
             _cases = [case_getter for case_getter in _get_case_getter_s(cases)]
+        elif cases is THIS_MODULE:
+            raise ValueError("`THIS_MODULE` should only be used in the `module` argument, not in the `cases` argument")
         else:
             # already a sequence
             _cases = [case_getter for c in cases for case_getter in _get_case_getter_s(c)]