session/test_env_select: Move direct tests to the top of the file

All but one of the tests in this test module are actually testing
env_select functionality through calling other code that in turn
uses env_select (CliEnv, EnvSelector and register_env_select_flags).

We move that one test to the top of the file, but we do not indicate
the boundary between the groups (or even explain that the grouping
exists) at the request of @gaborbernat.

Author: 0cjs

tests/session/test_env_select.py

@@ -16,6 +16,14 @@
 CURRENT_PY_ENV = f"py{sys.version_info[0]}{sys.version_info[1]}"  # e.g. py310
 
 
+def test_env_select_lazily_looks_at_envs() -> None:
+    state = State(get_options(), [])
+    env_selector = EnvSelector(state)
+    # late-assigning env should be reflected in env_selector
+    state.conf.options.env = CliEnv("py")
+    assert set(env_selector.iter()) == {"py"}
+
+
 def test_label_core_can_define(tox_project: ToxProjectCreator) -> None:
     ini = """
         [tox]
@@ -130,14 +138,6 @@ def test_tox_skip_env_logs(tox_project: ToxProjectCreator, monkeypatch: MonkeyPa
     outcome.assert_out_err("ROOT: skip environment mypy, matches filter 'm[y]py'\npy310\npy39\n", "")
 
 
-def test_env_select_lazily_looks_at_envs() -> None:
-    state = State(get_options(), [])
-    env_selector = EnvSelector(state)
-    # late-assigning env should be reflected in env_selector
-    state.conf.options.env = CliEnv("py")
-    assert set(env_selector.iter()) == {"py"}
-
-
 def test_cli_env_can_be_specified_in_default(tox_project: ToxProjectCreator) -> None:
     proj = tox_project({"tox.ini": "[tox]\nenv_list=exists"})
     outcome = proj.run("r", "-e", "exists")