scripts: tests: twister: Add error testing

Errors did not have their dedicated test file.
This change adds it to the repo and
checks the only non-def statement there.

Signed-off-by: Lukasz Mrugala <lukaszx.mrugala@intel.com>

scripts/tests/twister/test_errors.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+"""
+Tests for the error classes
+"""
+
+import os
+import pytest
+
+from pathlib import Path
+from twisterlib.error import ConfigurationError
+
+def test_configurationerror():
+    cfile = Path('some') / 'path'
+    message = 'dummy message'
+
+    expected_err = f'{os.path.join("some", "path")}: dummy message'
+
+    with pytest.raises(ConfigurationError, match=expected_err):
+        raise ConfigurationError(cfile, message)