pythonunittest(2)

Setting up and tearing down a test harness.With the following steps, we will setup and
teardown a test harness for each test method.
1. Create a new file called recipe2.py in which to put all our code for this recipe.

2. Pick a class to test. In this case, we will use a slightly altered version of our Roman
numeral converter, where the function, not the constructor, provides the input value
to convert.

3. Create a test class using the same name as the class under test with Test appended
to the end.

4. Create a setUp method that creates an instance of the class under test.

5. Create a tearDown method that destroys the instance of the class under test.

6. Create all the test methods using self.converter.

7. Make the entire script runnable and then use the test runner of unittest.
if __name__ == "__main__":
unittest.main()

8. Run the file from the command line.

附源码：

# !usr/bin/env python 2.7
# coding: utf-8
# filename: recipe2.py

class RomanNumeralConverter(object):
    def __init__(self):
        self.digit_map = {"M":1000, "D":500, "C":100, "L":50, "X":10, "V":5, "I":1}

    def convert_to_decimal(self, roman_numeral):
        val = 0
        for char in roman_numeral:
            val += self.digit_map[char]
        return val

import unittest

class RomanNumeralConverterTest(unittest.TestCase):
    def setUp(self):
        print "Creating a new RomanNumeralConverter..."
        self.cvt = RomanNumeralConverter()

    def tearDown(self):
        print "Destroying the RomanNumeralConverter..."
        self.cvt = None

    def test_parsing_millenia(self):
        self.assertEquals(1000, \
                          self.cvt.convert_to_decimal("M"))

    def test_parsing_century(self):
        self.assertEquals(100, \
                          self.cvt.convert_to_decimal("C"))

    def test_parsing_half_century(self):
        self.assertEquals(50, \
                          self.cvt.convert_to_decimal("L"))

    def test_parsing_decade(self):
        self.assertEquals(10, \
                          self.cvt.convert_to_decimal("X"))

    def test_parsing_half_decade(self):
        self.assertEquals(5, self.cvt.convert_to_decimal("V"))

    def test_parsing_one(self):
        self.assertEquals(1, self.cvt.convert_to_decimal("I"))

    def test_empty_roman_numeral(self):
        self.assertTrue(self.cvt.convert_to_decimal("") == 0)
        self.assertFalse(self.cvt.convert_to_decimal("") > 0)

    def test_no_roman_numeral(self):
        self.assertRaises(TypeError, \
                          self.cvt.convert_to_decimal, None)

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

结果：

Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.Creating a new RomanNumeralConverter...
Destroying the RomanNumeralConverter...
.
----------------------------------------------------------------------
Ran 8 tests in 0.001s

OK

由结果可以看出，每一个testcase均会重新装载setUp一次