Use the shared zeroconf instance when attempting to create another Zeroconf instance (#38744)

tests/components/zeroconf/test_usage.py

@@ -0,0 +1,56 @@
+"""Test Zeroconf multiple instance protection."""
+import zeroconf
+
+from homeassistant.components.zeroconf import async_get_instance
+from homeassistant.components.zeroconf.usage import install_multiple_zeroconf_catcher
+
+from tests.async_mock import Mock, patch
+
+
+async def test_multiple_zeroconf_instances(hass, mock_zeroconf, caplog):
+    """Test creating multiple zeroconf throws without an integration."""
+
+    zeroconf_instance = await async_get_instance(hass)
+
+    install_multiple_zeroconf_catcher(zeroconf_instance)
+
+    new_zeroconf_instance = zeroconf.Zeroconf()
+    assert new_zeroconf_instance == zeroconf_instance
+
+    assert "Zeroconf" in caplog.text
+
+
+async def test_multiple_zeroconf_instances_gives_shared(hass, mock_zeroconf, caplog):
+    """Test creating multiple zeroconf gives the shared instance to an integration."""
+
+    zeroconf_instance = await async_get_instance(hass)
+
+    install_multiple_zeroconf_catcher(zeroconf_instance)
+
+    correct_frame = Mock(
+        filename="/config/custom_components/burncpu/light.py",
+        lineno="23",
+        line="self.light.is_on",
+    )
+    with patch(
+        "homeassistant.helpers.frame.extract_stack",
+        return_value=[
+            Mock(
+                filename="/home/dev/homeassistant/core.py",
+                lineno="23",
+                line="do_something()",
+            ),
+            correct_frame,
+            Mock(
+                filename="/home/dev/homeassistant/components/zeroconf/usage.py",
+                lineno="23",
+                line="self.light.is_on",
+            ),
+            Mock(filename="/home/dev/mdns/lights.py", lineno="2", line="something()",),
+        ],
+    ):
+        assert zeroconf.Zeroconf() == zeroconf_instance
+
+    assert "custom_components/burncpu/light.py" in caplog.text
+    assert "23" in caplog.text
+    assert "self.light.is_on" in caplog.text