[TESTING] new exceptions file in tests (- WIP #157 -).

New file tests/exceptions.py:
  - initial implementation of `CommandExecutionError`

Author: reactive-firewall

tests/exceptions.py

@@ -0,0 +1,8 @@
+# header placeholder
+
+__module__ = "tests.exceptions"
+
+class CommandExecutionError(RuntimeError):
+	def __init__(self, message, exit_code, *args, **kwargs):
+		super().__init__(message, *args, **kwargs)
+		self.exit_code = exit_code