added test for error_handler

tests/test_error_handler.py

@@ -0,0 +1,50 @@
+import sys
+from unittest.mock import Mock
+
+import pytest
+
+from broqer.error_handler import default_error_handler
+
+
+def test_default(capsys):
+    try:
+        0/0
+    except:
+        exc = sys.exc_info()
+
+    default_error_handler(*exc)
+
+    captured = capsys.readouterr()
+
+    assert captured.err.startswith('Traceback (most recent call last):')
+    assert 'ZeroDivisionError: division by zero' in captured.err
+    assert __file__ in captured.err
+
+    assert captured.out == ''
+
+
+def test_set_errorhandler(capsys):
+    mock = Mock()
+    default_error_handler.set(mock)
+
+    try:
+        0/0
+    except:
+        exc = sys.exc_info()
+
+    default_error_handler(*exc)
+
+    mock.assert_called_once_with(*exc)
+
+    captured = capsys.readouterr()
+
+    assert captured.err == ''
+    assert captured.out == ''
+
+    # reset
+    default_error_handler.reset()
+
+    default_error_handler(*exc)
+
+    captured = capsys.readouterr()
+    assert captured.err.startswith('Traceback (most recent call last):')