Jail doctestplus outputs in tmpdir.

Co-authored-by: James Davies <[email protected]>

pytest_doctestplus/plugin.py

@@ -51,6 +51,23 @@ def __exit__(self, *args, **kwargs):
 """.lstrip()
 
 
+@pytest.fixture(autouse=True)
+def _docdir(request):
+    """Run doctests in isolated tmpdir so outputs do not end up in repo"""
+    # Trigger ONLY for doctestplus
+    doctest_plugin = request.config.pluginmanager.getplugin("doctestplus")
+    if isinstance(request.node, doctest_plugin._doctest_textfile_item_cls):
+        # Don't apply this fixture to io.rst.  It reads files and doesn't write
+        if "io.rst" not in request.node.name:
+            tmpdir = request.getfixturevalue('tmpdir')
+            with tmpdir.as_cwd():
+                yield
+        else:
+            yield
+    else:
+        yield
+
+
 # these pytest hooks allow us to mark tests and run the marked tests with
 # specific command line options.
 def pytest_addoption(parser):