https://github.com/tox-dev/toml-fmt/issues/120

--- pyproject_fmt-2.11.1/pyproject.toml.orig
+++ pyproject_fmt-2.11.1/pyproject.toml
@@ -95,7 +95,7 @@
 
 [tool.pytest]
 ini_options.testpaths = [
-  "tests",
+  "pyproject-fmt/tests",
 ]
 
 [tool.coverage]