[uart_mux] New component to share a UART between a CDC-ACM bridge and local consumers (#19066)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: J. Nick Koston <nick@koston.org>

tests/component_tests/uart_mux/test_init.py

@@ -0,0 +1,42 @@
+"""Tests for the uart_mux component's final validation."""
+
+import pytest
+
+from esphome import config_validation as cv
+from esphome.const import CONF_ID, PlatformFramework
+from esphome.core import ID
+from esphome.types import ConfigType
+from tests.component_tests.types import SetCoreConfigCallable
+
+CONF_BRIDGE_ID = "bridge_id"
+
+
+def _set_esp32_s3(set_core_config: SetCoreConfigCallable) -> None:
+    from esphome.components.esp32 import KEY_VARIANT, VARIANT_ESP32S3
+
+    set_core_config(
+        PlatformFramework.ESP32_IDF, platform_data={KEY_VARIANT: VARIANT_ESP32S3}
+    )
+
+
+def _mux_conf(mux_id: str, bridge_id: str) -> ConfigType:
+    return {CONF_ID: ID(mux_id), CONF_BRIDGE_ID: ID(bridge_id)}
+
+
+def test_accepts_one_mux_per_bridge(set_core_config: SetCoreConfigCallable) -> None:
+    _set_esp32_s3(set_core_config)
+    from esphome.components import uart_mux
+
+    uart_mux._final_validate(_mux_conf("mux_0", "bridge_0"))
+    uart_mux._final_validate(_mux_conf("mux_1", "bridge_1"))
+
+
+def test_rejects_two_muxes_on_one_bridge(
+    set_core_config: SetCoreConfigCallable,
+) -> None:
+    _set_esp32_s3(set_core_config)
+    from esphome.components import uart_mux
+
+    uart_mux._final_validate(_mux_conf("mux_0", "bridge_0"))
+    with pytest.raises(cv.Invalid, match="already routed by another 'uart_mux'"):
+        uart_mux._final_validate(_mux_conf("mux_1", "bridge_0"))