import unittest
import stackless
import gc


class SchedulingMonitor:
    "A scheduling monitor acting as a callback for set_schedule_callback()."

    def __init__(self):
        self.count = 0

    def __call__(self, prevTasklet, nextTasklet):
        self.count += 1

class SchedulingCallbackTestCase(unittest.TestCase):
    "A collection of scheduling callback tests."
    def setUp(self):
        gc.collect() #to avoid unexpected GC

    def test0(self):
        "Test #callbacks before and after running isolated monitor."

        mon1 = SchedulingMonitor()
        stackless.set_schedule_callback(mon1)
        stackless.tasklet(stackless.test_cframe)(3)
        stackless.tasklet(stackless.test_cframe)(3)
        # precondition
        self.assertEqual(mon1.count, 0,
            "No callbacks before running")
        # running
        stackless.run()
        # postcondition
        self.assertGreaterEqual(
            mon1.count, 2*3,
            "At least as may callbacks as many test_cframe calls")


    def test1(self):
        "Test multiple monitors, from test/test_set_schedule_callback.py"

        fu = self.assertTrue
        n = 2

        mon1 = SchedulingMonitor()
        stackless.set_schedule_callback(mon1)
        v = 3
        for i in range(n): stackless.tasklet(stackless.test_cframe)(v)
        c1 = mon1.count
        fu(c1 == 0, "No callbacks before running")
        stackless.run()
        c1 = mon1.count
        fu(c1 >= n*v, "At least as may callbacks as many test_cframe calls")

        mon2 = SchedulingMonitor()
        stackless.set_schedule_callback(mon2)
        v = 5
        for i in range(n): stackless.tasklet(stackless.test_cframe)(v)
        stackless.run()
        c2 = mon2.count
        fu(c2 >= n*v, "At least as may callbacks as many test_cframe calls")
        fu(mon1.count == c1, "No calls to previous callback")
        fu(c2 > c1, "More test_cframe calls => more callbacks on second run")

        stackless.set_schedule_callback(None)
        v = 7
        for i in range(n): stackless.tasklet(stackless.test_cframe)(v)
        stackless.run()
        c1p = mon1.count
        c2p = mon2.count
        fu(c1p == c1, "No calls to previous callback after setting it to None")
        fu(c2p == c2, "No calls to previous callback after setting it to None")


if __name__ == "__main__":
    unittest.main()