run each test on its own temp dir

tests/conftest.py

@@ -1,8 +1,21 @@
+import sys
 from pathlib import Path
 
 import pytest
 
 
+# each test runs on cwd to its temp dir
+@pytest.fixture(autouse=True)
+def go_to_tmpdir(request):
+    # Get the fixture dynamically by its name.
+    tmpdir = request.getfixturevalue("tmpdir")
+    # ensure local test created packages can be imported
+    sys.path.insert(0, str(tmpdir))
+    # Chdir only for the duration of the test.
+    with tmpdir.as_cwd():
+        yield
+
+
 @pytest.fixture
 def temp_dir(tmp_path: Path):
     """Create a temporary directory with some files inside it.