Add mock for tests

python/grass/script/tests/conftest.py

@@ -0,0 +1,20 @@
+"""Fixtures for grass.script"""
+
+import pytest
+
+
+@pytest.fixture
+def mock_no_session(monkeypatch):
+    """Set the environment variables as if there would be no background session.
+
+    Use with usefixtures (not as a paramter) to avoid warnings about an unused
+    parameter::
+
+        @pytest.mark.usefixtures("mock_no_session")
+        def test_session_handling():
+            pass
+
+    There may or may not be a session in the background (we don't check either way).
+    """
+    monkeypatch.delenv("GISRC", raising=False)
+    monkeypatch.delenv("GISBASE", raising=False)