Fix inverted logic in TracebackHandler.abort

Author: domdfcoding

consolekit/tracebacks.py

@@ -103,7 +103,7 @@ def abort(self, msg: Union[str, List[str]]) -> "NoReturn":
 			If a list of strings the strings are concatenated (i.e. ``''.join(msg)``).
 		"""
 
-		if isinstance(msg, str):
+		if not isinstance(msg, str):
 			msg = ''.join(msg)
 
 		if msg:

tests/test_tracebacks.py

@@ -186,3 +186,18 @@ def main(show_traceback: bool):
 	result = cli_runner.invoke(main, args="-h")
 	result.check_stdout(file_regression)
 	assert result.exit_code == 0
+
+
+def test_traceback_handler_abort(capsys):
+
+	TH = TracebackHandler(ValueError("foo"))
+
+	with pytest.raises(ValueError, match="foo$"):
+		TH.abort("Hello World")
+
+	assert capsys.readouterr().err == "Hello World\n"
+
+	with pytest.raises(ValueError, match="foo$"):
+		TH.abort(["Hello", "Everybody"])
+
+	assert capsys.readouterr().err == "HelloEverybody\n"