pytest Fixtures and Plugin Interoperability: Managing Session-Scoped State

When integrating custom pytest plugins with session-scoped fixtures, there is a potential for state leakage across disparate test modules. While pytest ensures that session-scoped fixtures persist for the duration of the test run, the interaction between plugin-defined fixtures and local conftest.py definitions can create implicit dependencies.

The primary goal is to ensure that session-level state managed by a plugin remains isolated or predictably reset when multiple plugins attempt to modify the same global resource. This becomes complex when parameterized fixtures are used to inject different configurations into a shared session resource.

• How does pytest resolve naming conflicts when a plugin and a local conftest.py both define a session-scoped fixture with the same name?
• What is the deterministic behavior for the teardown order when a session-scoped plugin fixture depends on a session-scoped local fixture?