[core] Stop parent git repos from breaking ESP-IDF/PlatformIO builds (#16994)

tests/unit_tests/test_espidf_toolchain.py

@@ -150,6 +150,20 @@ def test_get_idedata_regenerates_on_corrupted_cache(setup_core: Path) -> None:
     assert result == {"cxx_path": "regen"}
 
 
+def test_get_idf_env_sets_git_ceiling_directories(setup_core: Path) -> None:
+    """The IDF env caps git's upward search at the config directory.
+
+    This stops ESP-IDF's `git describe` from walking into an uninitialized or
+    corrupt git repo in a parent directory and failing the build.
+    """
+    toolchain._cache().env.clear()
+    # Set IDF_PATH so the framework-install branch is skipped.
+    with patch.dict(os.environ, {"IDF_PATH": str(setup_core)}):
+        env = toolchain._get_idf_env(version="5.5.4")
+    assert CORE.config_dir == setup_core
+    assert str(CORE.config_dir) in env["GIT_CEILING_DIRECTORIES"].split(os.pathsep)
+
+
 def test_get_core_framework_version_from_core_data():
     """The version is read from CORE.data when validation populated it."""
     from esphome.components.esp32.const import KEY_ESP32, KEY_IDF_VERSION

tests/unit_tests/test_helpers.py

@@ -196,6 +196,33 @@ def test_is_ha_addon(monkeypatch, value, expected):
     assert actual == expected
 
 
+def test_add_git_ceiling_directory_sets_when_unset():
+    """An empty env gets GIT_CEILING_DIRECTORIES set to the directory."""
+    env: dict[str, str] = {}
+    directory = Path("/home/user/config")
+    helpers.add_git_ceiling_directory(env, directory)
+    assert env["GIT_CEILING_DIRECTORIES"] == str(directory)
+
+
+def test_add_git_ceiling_directory_appends_to_existing():
+    """An existing value is preserved and the new directory is appended."""
+    env = {"GIT_CEILING_DIRECTORIES": str(Path("/some/ceiling"))}
+    directory = Path("/home/user/config")
+    helpers.add_git_ceiling_directory(env, directory)
+    assert env["GIT_CEILING_DIRECTORIES"].split(os.pathsep) == [
+        str(Path("/some/ceiling")),
+        str(directory),
+    ]
+
+
+def test_add_git_ceiling_directory_skips_duplicate():
+    """A directory already in the list is not appended again."""
+    directory = Path("/home/user/config")
+    env = {"GIT_CEILING_DIRECTORIES": str(directory)}
+    helpers.add_git_ceiling_directory(env, directory)
+    assert env["GIT_CEILING_DIRECTORIES"] == str(directory)
+
+
 def test_walk_files(fixture_path):
     path = fixture_path / "helpers"
 

tests/unit_tests/test_platformio_toolchain.py

@@ -304,6 +304,11 @@ def test_run_platformio_cli_sets_environment_variables(
         )
         assert "PLATFORMIO_LIBDEPS_DIR" in os.environ
         assert "PYTHONWARNINGS" in os.environ
+        # Caps git's upward search at the config dir so an uninitialized or
+        # corrupt parent git repo can't break the framework's `git describe`.
+        assert str(CORE.config_dir) in os.environ["GIT_CEILING_DIRECTORIES"].split(
+            os.pathsep
+        )
 
         # Check command was called correctly — runs PlatformIO as a subprocess
         # via the esphome.platformio.runner entry point.