# Copyright (c) 2009 Tim Freeman
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# (This is the standard MIT License, copied from
# http://www.opensource.org/licenses/mit-license.php on 24 Apr 2007.)
#desc Utilities for unit tests to call.
import traceback
import StringIO
import sys

def with_output_to_string(f):
    # Invoke the given function, with no arguments.
    # Return a dict with these keys:
    # result -- The value returned by f, or None if it raised an exception.
    # exception -- The exception raised by f, or None if it returned normally.
    # output -- The text written to sys.stdout during the time f was running.
    exception = None
    result = None
    o = sys.stdout
    stringio = StringIO.StringIO()
    sys.stdout = stringio
    try:
        result = f()
    except:
        exception = sys.exc_info()[1]
    sys.stdout = o
    return {"result":result, "exception":exception,
            "output":stringio.getvalue()}

def expect_exception(f):
    # Invoke the given function.
    # Throw an exception if f returns normally, and return the exception if f
    # throws one.
    threw = False
    try:
        f()
    except:
        return sys.exc_info()[1]
    raise Exception("The function should have thrown an exception, "
                    "but it didn't.")

def assert_equals(v1, v2):
    # Experiments show that assert does not compute its second
    # argument when the first argument is True. 
    assert v1 == v2, "Should have been equal: %r, %r" % (v1, v2)

def assert_in(v1, v2):
    """Assert that v1 is in v2, and print useful information if we fail."""
    assert v1 in v2, "%r should have been in %r" % (v1, v2)

# Put print_exc and print_stack here so I don't have to keep going
# back to the documentation to remember how to spell them.
def print_exc():
    traceback.print_exc()

def print_stack():
    traceback.print_stack()