issue2551142 - Import of retired node ... unique constraint failure. Title: Import of retired node with username after active node fails with unique constraint failure. More fixes needed for mysql and postgresql. mysql: add unique constraint for (keyvalue, __retired__) when creating class in the database. On schema change if class is changed, remove the unique constraint too. upgrade version of rdbms database from 5 to 6 to add constraint to all version 5 databases that were created as version 5 and didn't get the unique constraint. Make no changes on version 5 databases upgraded from version 4, the upgrade process to 5 added the constraint. Make no changes to other databases (sqlite, postgres) during upgrade from version 5 to 6. postgres: Handle the exception raised on unique constraint violation. The exception invalidates the database connection so it can't be used to recover from the exception. Added two new database methods: checkpoint_data - performs a db.commit under postgres does nothing on other backends restore_connection_on_error - does a db.rollback on postgres, does nothing on other backends with the rollback() done on the connection I can use the database connection to fixup the import that failed on the unique constraint. This makes postgres slower but without the commit after every imported object, the rollback will delete all the entries done up to this point. Trying to figure out how to make the caller do_import batch and recover from this failure is beyond me. Also dismissed having to process the export csv file before importing. Pushing that onto a user just seems wrong. Also since import/export isn't frequently done the lack of surprise on having a failing import and reduced load/frustration for the user seems worth it. Also the import can be run in verbose mode where it prints out a row as it is processed, so it may take a while, ut the user can get feedback. db_test-base.py: add test for upgrade from 5 to 6.

import unittest
import os, sys, shutil

from roundup.demo import install_demo, run_demo

import roundup.scripts.roundup_server

# https://stackoverflow.com/questions/4219717/how-to-assert-output-with-nosetest-unittest-in-python
# lightly modified
from contextlib import contextmanager
_py3 = sys.version_info[0] > 2
if _py3:
    from io import StringIO # py3
else:
    from StringIO import StringIO # py2
@contextmanager
def captured_output():
    new_out, new_err = StringIO(), StringIO()
    old_out, old_err = sys.stdout, sys.stderr
    try:
        sys.stdout, sys.stderr = new_out, new_err
        yield sys.stdout, sys.stderr
    finally:
        sys.stdout, sys.stderr = old_out, old_err

class TestDemo(unittest.TestCase):
    def setUp(self):
        self.home = os.path.abspath('_test_demo')

    def tearDown(self):
        try:
            shutil.rmtree(self.home)
        except FileNotFoundError:
            pass
        
    def testDemo(self):
        with captured_output() as (out, err):
            install_demo(self.home, 'anydbm', 'classic')
        output = out.getvalue().strip()
        print(output)

        # dummy up the return of get_server so the serve_forever method
        # raises keyboard interrupt exiting the server so the test exits.
        gs = roundup.scripts.roundup_server.ServerConfig.get_server
        def raise_KeyboardInterrupt():
            raise KeyboardInterrupt

        def test_get_server(self):
            httpd = gs(self)
            httpd.serve_forever = raise_KeyboardInterrupt
            return httpd

        roundup.scripts.roundup_server.ServerConfig.get_server = test_get_server

        # Run under context manager to capture output of startup text.
        with captured_output() as (out, err):
            run_demo(self.home)
        output = out.getvalue().strip()
        print(output)
        # if the server installed and started this will be the
        # last line in the output.
        self.assertIn("Keyboard Interrupt: exiting", output.split('\n'))