test(termux): exercise shared extensions and reject stale scratch data

tests/test_termux_python_linkage.py

@@ -14,11 +14,11 @@ from scripts.termux import python_linkage
 
 @pytest.mark.platforms("linux")
 def test_python_symbols_gain_an_explicit_library_dependency(tmp_path):
-    import _ctypes
+    import _cffi_backend
 
     library = Path(sysconfig.get_config_var("LIBDIR")) / sysconfig.get_config_var("LDLIBRARY")
-    extension = tmp_path / Path(_ctypes.__file__).name
-    shutil.copy2(_ctypes.__file__, extension)
+    extension = tmp_path / Path(_cffi_backend.__file__).name
+    shutil.copy2(_cffi_backend.__file__, extension)
     original = subprocess.check_output(["patchelf", "--print-needed", str(extension)], text=True).splitlines()
     for name in original:
         if name.startswith("libpython"):
@@ -29,7 +29,7 @@ def test_python_symbols_gain_an_explicit_library_dependency(tmp_path):
     assert soname in needed
     assert not python_linkage.link_extension(extension, library), "a second pass must not edit a correct extension"
     subprocess.run(
-        [sys.executable, "-c", "import _ctypes; print(_ctypes.__file__)"],
+        [sys.executable, "-c", "import _cffi_backend; print(_cffi_backend.__file__)"],
         cwd=tmp_path, check=True,
     )
 

tests/test_termux_runtime_libs.py

@@ -160,8 +160,6 @@ def test_stage_cache_correctness(tmp_path, lib_source, corruption):
 
     # True cache hit: source deleted, no downloads possible.
     server.stop()
-    for p in (tmp_path / "payload" / ".work").rglob("*"):
-        pass
     import shutil
     shutil.rmtree(tmp_path / "payload" / ".work")
     assert srl.stage(tmp_path / "payload", table) == out
@@ -207,9 +205,12 @@ def test_collision_identical_ok_conflicting_raises(tmp_path, lib_source):
         srl.stage(tmp_path / "payload", table)
 
 
-def test_main_thin_caller(tmp_path):
-    """main() is a thin wrapper over stage() reading runtime_libs.json."""
-    import importlib
-    mod = importlib.reload(srl)
-    assert callable(mod.stage)
-    assert callable(mod.main)
+def test_stale_scratch_cannot_poison_a_rebuilt_cache(tmp_path, lib_source):
+    _, table = lib_source
+    out = _stage(tmp_path, table)
+    expected = (out / "liba.so").read_bytes()
+    scratch = tmp_path / "payload/.work/runtime-libs/extract/liba" / PREFIX / "lib/liba.so"
+    scratch.write_bytes(b"corrupted scratch bytes")
+    (out / "liba.so").unlink()
+    srl.stage(tmp_path / "payload", table)
+    assert (out / "liba.so").read_bytes() == expected