Improve dispatcher typing (#106872)

tests/helpers/test_dispatcher.py

@@ -5,6 +5,7 @@ import pytest
 
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.helpers.dispatcher import (
+    SignalType,
     async_dispatcher_connect,
     async_dispatcher_send,
 )
@@ -30,6 +31,32 @@ async def test_simple_function(hass: HomeAssistant) -> None:
     assert calls == [3, "bla"]
 
 
+async def test_signal_type(hass: HomeAssistant) -> None:
+    """Test dispatcher with SignalType."""
+    signal: SignalType[str, int] = SignalType("test")
+    calls: list[tuple[str, int]] = []
+
+    def test_funct(data1: str, data2: int) -> None:
+        calls.append((data1, data2))
+
+    async_dispatcher_connect(hass, signal, test_funct)
+    async_dispatcher_send(hass, signal, "Hello", 2)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2)]
+
+    async_dispatcher_send(hass, signal, "World", 3)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2), ("World", 3)]
+
+    # Test compatibility with string keys
+    async_dispatcher_send(hass, "test", "x", 4)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2), ("World", 3), ("x", 4)]
+
+
 async def test_simple_function_unsub(hass: HomeAssistant) -> None:
     """Test simple function (executor) and unsub."""
     calls1 = []