🐛 fix(coverage): handle version-specific coverage gaps

On 3.10 the "venv" sysconfig scheme doesn't exist, making several code
paths unreachable. On 3.12 in CI tkinter is unavailable, skipping the
test body. Use version pragmas and pytest.importorskip accordingly.

Author: gaborbernat

src/py_discovery/_py_info.py

@@ -95,7 +95,7 @@ def abs_path(v):
 
         scheme_names = sysconfig.get_scheme_names()
 
-        if "venv" in scheme_names:
+        if "venv" in scheme_names:  # pragma: >=3.11 cover
             self.sysconfig_scheme = "venv"
             self.sysconfig_paths = {
                 i: sysconfig.get_path(i, expand=False, scheme=self.sysconfig_scheme) for i in sysconfig.get_path_names()
@@ -223,11 +223,11 @@ def _fast_get_system_executable(self):
             return None
 
         # We're not in a venv and base_executable exists; use it directly
-        if os.path.exists(base_executable):
+        if os.path.exists(base_executable):  # pragma: >=3.11 cover
             return base_executable
 
         # Try fallback for POSIX virtual environments
-        return self._try_posix_fallback_executable(base_executable)
+        return self._try_posix_fallback_executable(base_executable)  # pragma: >=3.11 cover
 
     def _try_posix_fallback_executable(self, base_executable):
         """Try to find a versioned Python binary as fallback for POSIX virtual environments.
@@ -266,7 +266,7 @@ def install_path(self, key: str) -> str:
 
         """
         result = self.distutils_install.get(key)
-        if result is None:  # pragma: no branch # distutils is empty when "venv" scheme is available
+        if result is None:  # pragma: >=3.11 cover # distutils is empty when "venv" scheme is available
             # set prefixes to empty => result is relative from cwd
             prefixes = self.prefix, self.exec_prefix, self.base_prefix, self.base_exec_prefix
             config_var = {k: "" if v in prefixes else v for k, v in self.sysconfig_vars.items()}

tests/conftest.py

@@ -25,5 +25,5 @@ def _ensure_py_info_cache_empty(session_cache: DiskCache) -> Generator[None]:
 @pytest.fixture
 def _skip_if_test_in_system(session_cache: DiskCache) -> None:
     current = PythonInfo.current(session_cache)
-    if current.system_executable is not None:  # pragma: no branch
+    if current.system_executable is not None:  # pragma: no cover
         pytest.skip("test not valid if run under system")

tests/test_py_info_extra.py

@@ -47,10 +47,7 @@ def test_get_tcl_tk_libs_returns_tuple() -> None:
 
 
 def test_get_tcl_tk_libs_tcl_error(mocker) -> None:
-    try:
-        import tkinter as tk
-    except ImportError:  # pragma: no cover
-        pytest.skip("tkinter not available")
+    tk = pytest.importorskip("tkinter")
 
     mock_tcl = MagicMock()
     mock_tcl.eval.side_effect = tk.TclError("fail")