import imp

from test.test_support import TestFailed, TestSkipped

try:

    import thread

except ImportError:

    raise TestSkipped("test only valid when thread support is available")

def verify_lock_state(expected):

    if imp.lock_held() != expected:

        raise TestFailed("expected imp.lock_held() to be %r" % expected)

def testLock():

    LOOPS = 50

    # The import lock may already be held, e.g. if the test suite is run

    # via "import test.autotest".

    lock_held_at_start = imp.lock_held()

    verify_lock_state(lock_held_at_start)

    for i in range(LOOPS):

        imp.acquire_lock()

        verify_lock_state(True)

    for i in range(LOOPS):

        imp.release_lock()

    # The original state should be restored now.

    verify_lock_state(lock_held_at_start)

    if not lock_held_at_start:

        try:

            imp.release_lock()

        except RuntimeError:

            pass

        else:

            raise TestFailed("release_lock() without lock should raise "

                             "RuntimeError")

def test_main():

    testLock()

if __name__ == "__main__":

    test_main()