[esp32] Restrict toolchain validation to supported values (#17972)

esphome/components/esp32/__init__.py

@@ -1031,7 +1031,9 @@ def _check_esp_idf_versions(config: ConfigType) -> ConfigType:
 
 
 def _validate_toolchain(value) -> Toolchain:
-    return Toolchain(cv.one_of(*(t.value for t in Toolchain), lower=True)(value))
+    return Toolchain(
+        cv.one_of(Toolchain.PLATFORMIO, Toolchain.ESP_IDF, lower=True)(value)
+    )
 
 
 def _resolve_toolchain(value: ConfigType) -> ConfigType:

tests/component_tests/esp32/test_esp32.py

@@ -108,6 +108,24 @@ def test_esp32_default_toolchain_is_esp_idf(
     assert CORE.toolchain == expected
 
 
+@pytest.mark.parametrize(
+    "config_toolchain",
+    [Toolchain.SDK_NRF.value, "nonsense"],
+)
+def test_esp32_rejects_unsupported_toolchains(
+    set_core_config: SetCoreConfigCallable,
+    config_toolchain: str,
+) -> None:
+    """Toolchains esp32 does not support are rejected at validation time."""
+    set_core_config(PlatformFramework.ESP32_IDF)
+
+    from esphome.components.esp32 import CONFIG_SCHEMA
+
+    CORE.toolchain = None
+    with pytest.raises(cv.Invalid, match="Unknown value"):
+        CONFIG_SCHEMA({"variant": VARIANT_ESP32, "toolchain": config_toolchain})
+
+
 @pytest.mark.parametrize(
     ("config", "error_match"),
     [