Function render_mock_server_setup 

pub fn render_mock_server_setup(
    out: &mut String,
    fixture: &Fixture,
    e2e_config: &E2eConfig,
)

Emit mock server setup lines into a test function body.

Builds MockRoute objects from the fixture’s mock_response and starts the server. The resulting mock_server variable is in scope for the rest of the test function.