[ci] Stop the toolchain tests from installing ESP-IDF (#20413)

tests/unit_tests/conftest.py

@@ -18,6 +18,7 @@ from unittest.mock import Mock, patch
 import pytest
 
 from esphome.core import CORE
+from esphome.espidf import toolchain
 
 here = Path(__file__).parent
 
@@ -26,6 +27,21 @@ package_root = here.parent.parent
 sys.path.insert(0, package_root.as_posix())
 
 
+@pytest.fixture(autouse=True)
+def _no_idf_install(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Fail any test that would install ESP-IDF for real.
+
+    An unmocked ``_get_idf_env`` reaches ``check_esp_idf_install``, which
+    downloads the framework on a bare CI runner (minutes on Windows). The
+    install path's own tests call it through ``esphome.espidf.framework``.
+    """
+
+    def refuse(*args: object, **kwargs: object) -> None:
+        raise AssertionError("test would install ESP-IDF; mock _get_idf_env")
+
+    monkeypatch.setattr(toolchain, "check_esp_idf_install", refuse)
+
+
 @pytest.fixture(autouse=True)
 def reset_core():
     """Reset CORE after each test."""

tests/unit_tests/test_espidf_toolchain.py

@@ -1519,6 +1519,7 @@ def test_run_reconfigure_flip_into_skip_mode_cleans_up(setup_core: Path) -> None
     with (
         patch.object(toolchain, "_skip_bootloader", return_value=True),
         patch.object(toolchain, "_get_idf_tool", side_effect=lambda n: f"/tools/{n}"),
+        patch.object(toolchain, "_get_idf_env", return_value={}),
         patch.object(toolchain, "_tool_env", return_value={}),
         patch.object(toolchain, "run_build_tool", return_value=0),
         patch.object(toolchain, "_idf_py") as mock_idf_py,
@@ -1542,6 +1543,7 @@ def test_run_reconfigure_skip_steady_state_cleans_nothing(setup_core: Path) -> N
     with (
         patch.object(toolchain, "_skip_bootloader", return_value=True),
         patch.object(toolchain, "_get_idf_tool", side_effect=lambda n: f"/tools/{n}"),
+        patch.object(toolchain, "_get_idf_env", return_value={}),
         patch.object(toolchain, "_tool_env", return_value={}),
         patch.object(toolchain, "run_build_tool", return_value=0),
         patch.object(toolchain, "_idf_py") as mock_idf_py,