Auto-discover pytest paths

Look for pytest paths in the `pyproject.toml` file and add them to
`extra_paths` automatically.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/repo/config/nox/config.py

@@ -84,6 +84,15 @@ class Config:
     tools invoked by the sessions.
     """
 
+    def __post_init__(self) -> None:
+        """Initialize the configuration object.
+
+        This will add extra paths discovered in config files and other sources.
+        """
+        for path in util.discover_paths():
+            if path not in self.extra_paths:
+                self.extra_paths.append(path)
+
     def copy(self, /) -> Self:
         """Create a new object as a copy of self.
 

src/frequenz/repo/config/nox/util.py

@@ -170,3 +170,30 @@ def min_dependencies() -> list[str]:
         else:
             raise RuntimeError(f"Minimum requirement is not set: {dep}")
     return min_deps
+
+
+def discover_paths() -> list[str]:
+    """Discover paths to check.
+
+    Discover the paths to check by looking into different sources, like the
+    `pyproject.toml` file.
+
+    Currently the following paths are discovered:
+
+    - The `testpaths` option in the `tools.pytest.ini_options` section of
+      `pyproject.toml`.
+
+    Returns:
+        The discovered paths to check.
+    """
+    with open("pyproject.toml", "rb") as toml_file:
+        data = tomllib.load(toml_file)
+
+    testpaths = (
+        data.get("tool", {})
+        .get("pytest", {})
+        .get("ini_options", {})
+        .get("testpaths", [])
+    )
+
+    return testpaths