Cleanup temporary hidden variable too

and use "___" instead of the more commonly used "_" to avoid any
potential naming collisions.

Tweak `test_requires_module_variable` to check that no output is
returned too.

Author: lagru

pytest_doctestplus/plugin.py

@@ -930,10 +930,10 @@ def _prepend_importorskip(self, test, *, module):
         """Prepends `pytest.importorskip` before the doctest."""
         source = (
             "import pytest; "
-            # Hide output of this statement in `_`, otherwise doctests fail
-            f"_ = pytest.importorskip({module!r}); "
+            # Hide output of this statement in `___`, otherwise doctests fail 
+            f"___ = pytest.importorskip({module!r}); "
             # Don't impact what's available in the namespace
-            "del pytest"
+            "del pytest; del ___"
         )
         importorskip = doctest.Example(source=source, want="")
         test.examples.insert(0, importorskip)

tests/test_doctestplus.py

@@ -1567,7 +1567,10 @@ def g():
 
 def test_requires_module_variable(testdir):
     p = testdir.makepyfile("""
-        __doctest_requires__ = {("f",): ["module_that_is_not_availabe"]}
+        __doctest_requires__ = {
+            ("f",): ["module_that_is_not_availabe"],
+            ("g",): ["pytest"],
+        }
 
         def f():
             '''