fix(coverage): broaden always-run-all and rung3 Fortran extension matching

Fix 3: ALWAYS_RUN_ALL_EXACT + prefixes enumerated only a handful of toolchain
files, missing case.py, build.py, common.py, state.py, sched.py, etc. Any
toolchain/mfc/*.py change (except cases.py) affects every test's generation
or execution, so under-enumeration was unsound. Replace with a catch-all:
any(f.startswith('toolchain/mfc/') and f.endswith('.py') and f != CASES_PY).
Drop the now-redundant individual file entries and toolchain/mfc/params/ and
toolchain/mfc/run/ prefixes (all subsumed). Keep CMakeLists.txt,
toolchain/cmake/, toolchain/bootstrap/, and src include rules.

Fix 4: rung 3 matched only .f90 and .f, missing .F90, .F95, .F03, .F08, .FOR
and all other uppercase/mixed variants. Changed files ending in those extensions
under src/ would fall through to per-test selection against a coverage map that
only tracks .fpp, causing silent under-inclusion. Fix: case-insensitive match
against the full tuple (.f90, .f, .f95, .f03, .f08, .for).

Tests: add three new unit tests covering the above fixes.

Author: sbryngelson

toolchain/mfc/test/coverage.py

@@ -47,19 +47,12 @@ def save_map(path: Path, entries: dict, *, n_tests: int, git_sha: str, gfortran_
 ALWAYS_RUN_ALL_EXACT = frozenset(
     [
         "CMakeLists.txt",
-        # Toolchain infra that affects EVERY test's generation/execution -> run all.
-        "toolchain/mfc/test/case.py",  # TestCase: how a case runs
-        "toolchain/mfc/test/test.py",  # the test runner
-        "toolchain/mfc/test/coverage.py",  # the selector itself
-        "toolchain/mfc/test/coverage_build.py",  # the map collector
     ]
 )
 ALWAYS_RUN_ALL_PREFIXES = (
     "src/common/include/",  # GPU/Fypp macro & include files (CPU map can't line-attribute)
     "toolchain/cmake/",  # build system
-    "toolchain/mfc/params/",  # parameter codegen -> emits Fortran broadly
     "toolchain/bootstrap/",  # build/run scripts
-    "toolchain/mfc/run/",  # .inp generation / case dicts -> affects every test's input
 )
 
 
@@ -69,6 +62,14 @@ def is_always_run_all(changed_files: set) -> bool:
         return True
     if any(f.startswith(ALWAYS_RUN_ALL_PREFIXES) for f in changed_files):
         return True
+    # Any toolchain/mfc/*.py change (params/, run/, test infra, case.py, common.py,
+    # build.py, state.py, sched.py, …) affects EVERY test's generation or execution and
+    # cannot be attributed to individual tests by the coverage map.  Treat the entire
+    # toolchain/mfc/ subtree as run-all EXCEPT cases.py, which is handled precisely by
+    # rung 5 (new/modified tests have a fresh param_hash absent from the map and run
+    # individually; unchanged tests have no .fpp overlap and are skipped).
+    if any(f.startswith("toolchain/mfc/") and f.endswith(".py") and f != CASES_PY for f in changed_files):
+        return True
     # gcov rolls #:include'd .fpp into the parent compilation unit, so include files
     # (inline_*.fpp, HardcodedIC, macros) are not reliably attributed in the map. Force a
     # full run for ANY src/**/include/ change so this attribution gap can never cause
@@ -112,8 +113,10 @@ def select_tests(cases, coverage_map, changed_files):
     if is_always_run_all(changed_files):
         return list(cases), [], "rung2: macro/codegen/build input changed"
 
-    # Rung 3: changed .f90/.f under src/ (map tracks .fpp only) -> run all.
-    if any(f.startswith("src/") and f.endswith((".f90", ".f")) for f in changed_files):
+    # Rung 3: changed hand-written Fortran source under src/ (map tracks .fpp only) -> run
+    # all.  Match case-insensitively to catch .F90, .F95, .FOR, etc.
+    _FORTRAN_EXTS = (".f90", ".f", ".f95", ".f03", ".f08", ".for")
+    if any(f.startswith("src/") and f.lower().endswith(_FORTRAN_EXTS) for f in changed_files):
         return list(cases), [], "rung3: hand-written .f90/.f changed"
 
     changed_fpp = {f for f in changed_files if f.endswith(".fpp")}

toolchain/mfc/test/test_coverage_unit.py

@@ -303,3 +303,22 @@ def test_docs_only_still_skips_all():
     cases = _cases("a")
     run, skip, reason = select_tests(cases, {"a": ["src/x.fpp"]}, {"README.md"})
     assert run == [] and len(skip) == 1 and "rung7" in reason
+
+
+def test_uppercase_fortran_extension_forces_all():
+    cases = _cases("a")
+    run, skip, reason = select_tests(cases, {"a": []}, {"src/common/m_x.F90"})
+    assert len(run) == 1 and reason.startswith("rung3")
+
+
+def test_toolchain_py_change_forces_all_except_cases():
+    assert is_always_run_all({"toolchain/mfc/case.py"})
+    assert is_always_run_all({"toolchain/mfc/build.py"})
+    assert is_always_run_all({"toolchain/mfc/common.py"})
+    assert not is_always_run_all({"toolchain/mfc/test/cases.py"})
+
+
+def test_empty_map_with_fpp_change_runs_all_rung4():
+    cases = _cases("a", "b")
+    run, skip, reason = select_tests(cases, {}, {"src/simulation/m_rhs.fpp"})
+    assert len(run) == 2 and reason.startswith("rung4")