add error tests

tests/test_errors.py

@@ -0,0 +1,26 @@
+import pytest
+
+import vban_cmd
+from tests import data, vban
+
+
+class TestErrors:
+    __test__ = True
+
+    def test_it_tests_an_unknown_kind(self):
+        with pytest.raises(
+            vban_cmd.error.VBANCMDError,
+            match=f"Unknown Voicemeeter kind 'unknown_kind'",
+        ):
+            vban_cmd.api("unknown_kind")
+
+    def test_it_tests_an_invalid_config(self):
+        EXPECTED_MSG = (
+            f"No config with name 'unknown' is loaded into memory",
+            f"Known configs: {list(vban.configs.keys())}",
+        )
+        with pytest.raises(vban_cmd.error.VBANCMDError) as exc_info:
+            vban.apply_config("unknown")
+
+        e = exc_info.value
+        assert e.message == "\n".join(EXPECTED_MSG)