tests/test-ctxmanager.py

obsolete: add operation metadata to rebase/amend/histedit obsmarkers

By recording what operation created the obsmarker, we can show very intuitive
messages to the user in various UIs. For instance, log output could have
messages like "Amended as XXX" to show why a commit is old and has an 'x' on it.

     @  ac28e3  durham
    /   First commit
   |
   | o  d4afe7 durham
   | |  Second commit
   | |
   | x  8e9a5d (Amended as ac28e3)  durham
   |/   First commit
   |

from __future__ import absolute_import

import silenttestrunner
import unittest

from mercurial import util

class contextmanager(object):
    def __init__(self, name, trace):
        self.name = name
        self.entered = False
        self.exited = False
        self.trace = trace

    def __enter__(self):
        self.entered = True
        self.trace(('enter', self.name))
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.exited = exc_type, exc_val, exc_tb
        self.trace(('exit', self.name))

    def __repr__(self):
        return '<ctx %r>' % self.name

class ctxerror(Exception):
    pass

class raise_on_enter(contextmanager):
    def __enter__(self):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

class raise_on_exit(contextmanager):
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.trace(('raise', self.name))
        raise ctxerror(self.name)

def ctxmgr(name, trace):
    return lambda: contextmanager(name, trace)

class test_ctxmanager(unittest.TestCase):
    def test_basics(self):
        trace = []
        addtrace = trace.append
        with util.ctxmanager(ctxmgr('a', addtrace), ctxmgr('b', addtrace)) as c:
            a, b = c.enter()
            c.atexit(addtrace, ('atexit', 'x'))
            c.atexit(addtrace, ('atexit', 'y'))
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'),
                                 ('atexit', 'y'), ('atexit', 'x'),
                                 ('exit', 'b'), ('exit', 'a')])

    def test_raise_on_enter(self):
        trace = []
        addtrace = trace.append
        with self.assertRaises(ctxerror):
            with util.ctxmanager(ctxmgr('a', addtrace),
                                 lambda: raise_on_enter('b', addtrace)) as c:
                c.enter()
                addtrace('unreachable')
        self.assertEqual(trace, [('enter', 'a'), ('raise', 'b'), ('exit', 'a')])

    def test_raise_on_exit(self):
        trace = []
        addtrace = trace.append
        with self.assertRaises(ctxerror):
            with util.ctxmanager(ctxmgr('a', addtrace),
                                 lambda: raise_on_exit('b', addtrace)) as c:
                c.enter()
                addtrace('running')
        self.assertEqual(trace, [('enter', 'a'), ('enter', 'b'), 'running',
                                 ('raise', 'b'), ('exit', 'a')])

if __name__ == '__main__':
    silenttestrunner.main(__name__)