adding tests to fix coverage and touch new code

tests/test_discovery.py

@@ -11,6 +11,19 @@ async def test_discovery(inverters_fixture):
     assert rt_api.inverter.__class__ == inverter_class
 
 
+@pytest.mark.asyncio
+async def test_discovery_with_model(inverters_fixture):
+    conn, inverter_class, _ = inverters_fixture
+    rt_api = await solax.real_time_api(*conn, "", inverter_class.__name__)
+    assert rt_api.inverter.__class__ == inverter_class
+
+
+@pytest.mark.asyncio
+async def test_discovery_unsupported_inverter():
+    with pytest.raises(DiscoveryError):
+        await solax.real_time_api("localhost", 2, "", "doesnotexist")
+
+
 @pytest.mark.asyncio
 async def test_discovery_no_host():
     with pytest.raises(DiscoveryError):