Install pytest

建立 PyCharm 專案後，在 Terminal 用 pip 安裝

pip install pytest

Pytest 官方文件：https://docs.pytest.org/

測試 Pytest 是否能正確執行

import math
 
 
def test_sqrt():
    num = 25
    assert math.sqrt(num) == 5
 
 
def test_square():
    num = 7
    assert 7 * 7 == 40      # 49
    # assert 7 * 7 == 49      # 49
 
 
def test_equality():
    # assert 10 == 11         # 10
    assert 10 != 11         # 10

第一個 unit test

hello.py

def hello_name(name):
    return f'Hello {name}'
 
 
if __name__ == '__main__':
    print(hello_name("Max"))

unittest

test_hello_unittest.py

import unittest
from hello import hello_name
 
 
class TestHello(unittest.TestCase):
    def test_hello_name(self):
        self.assertEqual(hello_name('Max'), 'Hello Max')

1. import unittest
2. 建立 TestHello (繼承 unittest.TestCase)
3. 在 TestHello 為每一個測試案何實作一個 method
4. 使用 self.assert* 來進行 assertions

執行 unittest

python -m unittest test_hello_unittest.py 
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

pytest

test_hello_pytest.py

from hello import hello_name
 
 
def test_hello_name():
    assert hello_name('Max') == 'Hello Max'
 

1. Pythonic
2. 支援 unittest test case
3. 只需要 assert，不需要記 assert.* (ex. assertEqual)
4. 更多的進階功能 (e.g., fixture, mark, parametrize and etc.)
5. 強大的套件

執行 pytest

$ pytest test_hello_pytest.py

"F" 表示測試沒有通過，如果出現 "." 則表示成功

執行 pytest

$ pytest -v test_hello_pytest.py

pytest fail message

$ pytest test_hello_pytest.py

"F" 表示測試沒有通過，如果出現 "." 則表示成功

pytest fail message

$ pytest -v test_hello_pytest.py

何謂單元測試(1/2)

何謂單元測試(2/3)

何謂單元測試(3/3)

PyCharm Demo

練習 test_hello.py (10分鐘)

名詞解釋-SUT

1st SUT 驗證

• 進入點(entry point): sum(a,b)
• 出口點(exit point): return value
  

def sum(a,b):
   result = int(a) + int(b)
   return result

2st SUT 驗證

• 進入點(entry point): M+(a)
• 出口點(exit point): MR(有時並沒有外部可存取的 getter)
  

3rd SUT 驗證

• 進入點(entry point): check(體溫)
• 出口點(exit point): disp(msg), 在電子看板秀警告文句
  

pytest-如何測試 exception 的狀況

test code (test_calculator.py)

def test_divide_by_zero():
    calculator = Calculator()
    # result = calculator.divide(9, 0)
    with pytest.raises(CalculatorError):
        result = calculator.divide(9, 0)

File names and function names

• By default pytest only identifies the file names starting with test_ or ending with _test as the test files.
• Pytest requires the test method names to start with "test" .

PyCharm Demo

練習 test_calculator.py (15分鐘)

• test_divide_by_zero()
• 請為 calculator.py 撰寫其他 function 的 unit test

pytest-Parametrizing tests

production code (triangle.py)

def type_of_triangle(a, b, c):
    if not is_valid_triangle(a, b, c):
        return "不是三角形"
    if (a == b) and (b == c):
        return "等邊三角形"
    elif (a == b) or (b == c) or (a == c):
        return "等腰三角形"
    elif (a * a + b * b == c * c) or (a * a + c * c == b * b) or (c * c + b * b == a * a):
        return "直角三角形"
    else:
        return "一般三角形"

pytest-Parametrizing tests

test code (test_triangle.py)

@pytest.mark.parametrize("a,b,c,expected", [
    (0, 1, 3, "不是三角形"),
    (1, 1, 1, "等邊三角形"),
    (2, 2, 3, "等腰三角形"),
    (3, 4, 5, "直角三角形"),
    (4, 5, 6, "一般三角形")
])
def test_type_of_triangle(a, b, c, expected):
    assert expected == type_of_triangle(a, b, c)

PyCharm Demo

練習 test_triangel.py (15分鐘)

• @pytest.mark.parametrize
• 請為 triangle.py 撰寫其他 function 的 unit test

pytest-Fixtures

在單元測試之前先建立好變數或物件，可重覆利用

@pytest.fixture()
def some_data():
    return 42
 
def test_some_data(some_data):
    """Return value for fixture."""
    assert some_data == 42
 
def test_inc_data(some_data):
    """Use fixture return value in a test."""
    inc_data = some_data + 1
    assert inc_data == 43

pytest -v test_fixtures.py

pytest-Fixtures

• 使用 Fixtures 來為單元測試作 setup/cleanup
• PyCharm Demo
• 練習 test_todo.py (15分鐘)

pytest-Fixtures: scope

controls how often a fixture gets set up and torn down.

pytest -v --setup-show test_scope.py

pytest-Fixtures: autouse

get a fixture to run all of the time

pytest -v -s test_autouse.py 

pytest-Fixtures: yield

• The code before the yield runs before each test;
• The code after the yield runs after the test.

pytest -v -s test_yield.py