Improve airq test coverage (#90192)

* Add a missing test for aborting with "already_configured"

Test that config_flow aborts with "already_configured" when the
integration has already been configured

* Don't copy test data

Since #90232 is merged, it is no longer needed

* Split the initialisation into two steps, as it should be

tests/components/airq/test_config_flow.py

@@ -11,6 +11,8 @@ from homeassistant.const import CONF_IP_ADDRESS, CONF_PASSWORD
 from homeassistant.core import HomeAssistant
 from homeassistant.data_entry_flow import FlowResultType
 
+from tests.common import MockConfigEntry
+
 pytestmark = pytest.mark.usefixtures("mock_setup_entry")
 
 TEST_USER_DATA = {
@@ -91,3 +93,25 @@ async def test_form_invalid_input(hass: HomeAssistant) -> None:
 
     assert result2["type"] == FlowResultType.FORM
     assert result2["errors"] == {"base": "invalid_input"}
+
+
+async def test_duplicate_error(hass: HomeAssistant) -> None:
+    """Test that errors are shown when duplicates are added."""
+    MockConfigEntry(
+        data=TEST_USER_DATA,
+        domain=DOMAIN,
+        unique_id=TEST_DEVICE_INFO["id"],
+    ).add_to_hass(hass)
+
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": config_entries.SOURCE_USER}
+    )
+
+    with patch("aioairq.AirQ.validate"), patch(
+        "aioairq.AirQ.fetch_device_info", return_value=TEST_DEVICE_INFO
+    ):
+        result2 = await hass.config_entries.flow.async_configure(
+            result["flow_id"], TEST_USER_DATA
+        )
+    assert result2["type"] == FlowResultType.ABORT
+    assert result2["reason"] == "already_configured"