MAINT-21: tests read and patch the Controller through tools/main_files.py

Prepares the split of app/main.py's Controller into files by job, with no app
change. tools/main_files.py gives a test the text and the AST of main.py plus
the files split from it, and `live`, which sets a global in every file whose
functions read it (and raises when none does). Tests that read main.py's
source, and tests and replay tools that patch a main global (datetime,
compute, resolve, _mono, WRITE_BUDGET_S, ...), go through it, so they pass on
this layout and on the split one. test_split_patches.py fails when a test or
tool patches an app.main attribute that main.py no longer reads, or that
another file also reads. tools/maint21_same_ast.py proves every function,
method and module-level assignment of main.py at the base is found unchanged
in its new file.

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/test_arbitrage.py

@@ -109,6 +109,8 @@ from app.validate import validate_startup_config
 
 UTC = timezone.utc
 HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, os.path.join(HERE, "tools"))
+import main_files  # noqa: E402
 
 # PRICE-02: `TariffPlan.arbitrage(now=...)` is required. This instant is before every
 # point these fixtures build, so no period has ended and the whole series counts.
@@ -779,9 +781,7 @@ check("...and cycle() calls it rather than inlining the conjunction, so a "
       "mutation back to a bare `engaged_now` is red rather than silent",
       "arbitrage.guard_state(self.peak_guard)" in
       ast.get_source_segment(
-          open(os.path.join(HERE, "app", "main.py"), encoding="utf-8").read(),
-          _fn(open(os.path.join(HERE, "app", "main.py"),
-                   encoding="utf-8").read(), "cycle")))
+          main_files.source(), _fn(main_files.source(), "cycle")))
 
 
 # --------------------------------------------------------------------------- #
@@ -907,8 +907,8 @@ check("a ZERO headroom does not cap a DISCHARGE. §9.1: 'discharge and export "
 # above calls decide() itself - and a required keyword-only parameter that no
 # caller fills is a TypeError only on the one path a suite does not run. Same
 # pin, same reason, as `weights=` in test_packshare.py part 10.
-_S45_MAIN = open(os.path.join(HERE, "app", "main.py"), encoding="utf-8").read()
-_S45_MAIN_TREE = ast.parse(_S45_MAIN)
+_S45_MAIN = main_files.source()
+_S45_MAIN_TREE = main_files.tree(_S45_MAIN)
 _s45_calls = [n for n in ast.walk(_S45_MAIN_TREE)
               if isinstance(n, ast.Call)
               and ast.unparse(n.func).endswith("arbitrage.decide")]
@@ -2215,8 +2215,7 @@ print()
 print("8. the background refresh - the tick must never await a fetch")
 
 
-_MAIN_SRC = derived(lambda: open(os.path.join(HERE, "app", "main.py"),
-                                 encoding="utf-8").read())
+_MAIN_SRC = derived(main_files.source)
 _cycle = derived(lambda: _fn(_MAIN_SRC, "cycle"))
 _refresh = derived(lambda: _fn(_MAIN_SRC, "run_tariff_refresh"))
 _read_inputs = derived(lambda: _fn(_MAIN_SRC, "read_inputs"))