nilmdb/tests/test_mustclose.py

import nilmdb
from nilmdb.utils.printf import *

import nose
from nose.tools import *
from nose.tools import assert_raises

from testutil.helpers import *

import sys
import cStringIO
import gc

err = cStringIO.StringIO()

@nilmdb.utils.must_close(errorfile = err)
class Foo:
    def __init__(self):
        fprintf(err, "Init\n")

    def __del__(self):
        fprintf(err, "Deleting\n")

    def close(self):
        fprintf(err, "Closing\n")

@nilmdb.utils.must_close(errorfile = err, wrap_verify = True)
class Bar:
    def __init__(self):
        fprintf(err, "Init\n")

    def __del__(self):
        fprintf(err, "Deleting\n")

    def close(self):
        fprintf(err, "Closing\n")

    def blah(self):
        fprintf(err, "Blah\n")

@nilmdb.utils.must_close(errorfile = err)
class Baz:
    pass

class TestMustClose(object):
    def test(self):

        # Note: this test might fail if the Python interpreter doesn't
        # garbage collect the object (and call its __del__ function)
        # right after a "del x".

        # Trigger error
        err.truncate()
        x = Foo()
        del x
        gc.collect()
        eq_(err.getvalue(),
            "Init\n"
            "error: Foo.close() wasn't called!\n"
            "Deleting\n")

        # No error
        err.truncate(0)
        y = Foo()
        y.close()
        del y
        gc.collect()
        eq_(err.getvalue(),
            "Init\n"
            "Closing\n"
            "Deleting\n")

        # Verify errors
        err.truncate(0)
        z = Bar()
        z.blah()
        z.close()
        with assert_raises(AssertionError):
            z.blah()
        # Since the most recent assertion references 'z',
        # we need to raise another assertion here so that
        # 'z' will get properly deleted.
        with assert_raises(AssertionError):
            raise AssertionError()
        del z
        gc.collect()
        eq_(err.getvalue(),
            "Init\n"
            "Blah\n"
            "Closing\n"
            "Deleting\n")

        # Class with missing methods
        err.truncate(0)
        w = Baz()
        w.close()
        del w
        eq_(err.getvalue(), "")