Merge branch '3.x'

1 files changed, 12 insertions, 0 deletions

diff --git a/sphinx/testing/fixtures.py b/sphinx/testing/fixtures.py
index 1008ea1b8..906163d56 100644
--- a/sphinx/testing/fixtures.py
+++ b/sphinx/testing/fixtures.py
@@ -245,3 +245,15 @@ def tempdir(tmpdir: str) -> "util.path":
     this fixture is for compat with old test implementation.
     """
     return util.path(tmpdir)
+
+
+@pytest.fixture
+def rollback_sysmodules():
+    """Rollback sys.modules to before testing to unload modules during tests."""
+    try:
+        sysmodules = list(sys.modules)
+        yield
+    finally:
+        for modname in list(sys.modules):
+            if modname not in sysmodules:
+                sys.modules.pop(modname)