test: add a test for zodb commmad and help driver

----

kirr: factor running `zodb ...` into zodbrun + add test for `zodb -h`.

Added test currently passes on py2, but fails on py3:

	out = <_io.TextIOWrapper encoding='UTF-8'>

	    def usage(out):
	        print("""\
	    Zodb is a tool for managing ZODB databases.

	    Usage:

	        zodb command [arguments]

	    The commands are:
	    """, file=out)

	        cmdv = command_dict.keys()
	>       cmdv.sort()
	E       AttributeError: 'dict_keys' object has no attribute 'sort'

	zodbtools/zodb.py:55: AttributeError

It will be fixed in the next patch.

setup.py

@@ -23,7 +23,7 @@ setup(
     install_requires = ['ZODB', 'zodburi', 'zope.interface', 'pygolang >= 0.0.0.dev6', 'six', 'dateparser'],
 
     extras_require = {
-                  'test': ['pytest', 'freezegun', 'pytz'],
+                  'test': ['pytest', 'freezegun', 'pytz', 'mock;python_version<="2.7"'],
     },
 
     entry_points= {'console_scripts': ['zodb = zodbtools.zodb:main']},

tox.ini

@@ -8,6 +8,7 @@ deps	=
     pytest
     freezegun
     pytz
+    mock;python_version<="2.7"
 
     # latest ZODB from ZODB3 series
     ZODB3:  ZODB3 >=3.10, <3.11dev

zodbtools/test/test_zodb.py

+# -*- coding: utf-8 -*-
+# Copyright (C) 2019  Nexedi SA and Contributors.
+#                     Jérome Perrin <jerome@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+
+import sys
+try:
+    from unittest import mock
+except ImportError:
+    # BBB python2
+    import mock
+
+import pytest
+
+from zodbtools import zodb
+from zodbtools import help as help_module
+
+
+# zodbrun runs zodb.main with argv and returns exit code + captured stdout/stderr.
+def zodbrun(capsys, *argv):
+    with mock.patch.object(sys, 'argv', ('zodb',) + argv), \
+         pytest.raises(SystemExit) as excinfo:
+        zodb.main()
+    assert len(excinfo.value.args) == 1
+    ecode = excinfo.value.args[0]
+    return ecode, capsys.readouterr()
+
+
+def test_main(capsys):
+    e, _ = zodbrun(capsys)
+    assert e == 2
+    assert "" == _.out
+    assert "Zodb is a tool for managing ZODB databases." in _.err
+
+    e, _ = zodbrun(capsys, '-h')
+    assert e == 0
+    assert "Zodb is a tool for managing ZODB databases." in _.out
+    assert "" == _.err
+
+
+@pytest.mark.parametrize(
+    "help_topic",
+    tuple(zodb.command_dict) + tuple(help_module.topic_dict))
+def test_help(capsys, help_topic):
+    e, _ = zodbrun(capsys, 'help', help_topic)
+    assert e == 0
+    assert _.err == ""
+    assert _.out != ""