Error in test exception

Question

This is my dummy class that I want to test:

class Meter:

    def __init__(self, meterInfo):
        self.b1pos = meterInfo['b1pos']


    def setMeter(self):
        print 'Initializing'
        try:
             print 'Connecting'
        except IOError as message:
            print message

    def readSignal(self, ele_name):
        try:
            if ele_name in ("b1", "b2"):
                readValue = 0.0
                readValue1 = 0.0
                return readValue, readValue1
            else:
                readValue = 0.0
                readValue1 = 0.0
                return readValue, readValue1
        except IOError as message:
            print message

And this is my unittest:

class TestMeter(unittest.TestCase):

    def testSetMeter(self):
        m = meter.Meter({'b1pos': 'b1pos'})
        self.assertRaises(IOError, m.setMeter())

    def testReadSignal(self):
        m = meter.Meter({'b1pos': 'b1pos'})
        a, b = m.readSignal('b1')
        self.assertTrue(isinstance(a, numbers.Number))
        self.assertTrue(isinstance(b, numbers.Number))
        self.assertRaises(IOError, m.readSignal('b1'))

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

For testSetMeter() I dont have any problems, but for testReadSignal() it gives me: "TypeError: 'tuple' object is not callable" I understand that this error is related to the return of radSignal, but how can I fix it? I tried with:

 def testReadSignal(self):
    m = meter.Meter({'b1pos': 'b1pos'})
    a, b = m.readSignal('b1')
    self.assertTrue(isinstance(a, numbers.Number))
    self.assertTrue(isinstance(b, numbers.Number))
    with self.assertRaises(IOError):
         m.readSignal('b1')

But this is the output:

AssertionError: IOError not raised

Answer 1

with

 self.assertRaises(Exception, m.readSignal('b1'))

I solved the problem