软件测试|Pytest 必会技巧（三）
作者：霍格沃兹测试开发学社
- 2023-10-16 北京
本文字数：2018 字
阅读完需：约 7 分钟
Pytest 参数化——pytest.mark.parametrize
parametrizing
首先来看一个实现检查一定的输入和期望输出测试功能的典型例子
# content of test_expectation.py
# coding:utf-8
import pytest@pytest.mark.parametrize("test_input,expected", [ ("3+5", 8), ("2+4", 6), ("6 * 9", 42), ])def test_eval(test_input, expected): assert eval(test_input) == expected
if __name__ == "__main__": pytest.main(["-s", "test_demo.py"])
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运行结果
============================= test session starts =============================collecting ... collected 3 items
test_demo.py::test_eval[3+5-8] test_demo.py::test_eval[2+4-6] test_demo.py::test_eval[6 * 9-42] PASSED [ 33%]PASSED [ 66%]FAILED [100%]test_demo.py:5 (test_eval[6 * 9-42])54 != 42
Expected :42Actual :54<Click to see difference>
test_input = '6 * 9', expected = 42
@pytest.mark.parametrize("test_input,expected", [ ("3+5", 8), ("2+4", 6), ("6 * 9", 42), ]) def test_eval(test_input, expected):> assert eval(test_input) == expectedE assert 54 == 42
test_demo.py:12: AssertionError
========================= 1 failed, 2 passed in 0.04s =========================
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在这个例子中设计的，只有一条输入/输出值的简单测试功能。和往常一样，函数的参数，你可以在运行结果看到在输入和输出值。
标记单个测试实例参数化
import pytest@pytest.mark.parametrize("test_input,expected", [ ("3+5", 8), ("2+4", 6), pytest.param("6 * 9", 42, marks=pytest.mark.xfail), ])def test_eval(test_input, expected): print("-------开始用例------") assert eval(test_input) == expected
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运行结果:
============================= test session starts =============================collecting ... collected 3 items
test_demo.py::test_eval[3+5-8] test_demo.py::test_eval[2+4-6] test_demo.py::test_eval[6 * 9-42]
======================== 2 passed, 1 xfailed in 0.06s =========================
Process finished with exit code 0PASSED [ 33%]-------开始用例------PASSED [ 66%]-------开始用例------XFAIL [100%]-------开始用例------
test_input = '6 * 9', expected = 42
@pytest.mark.parametrize("test_input,expected", [ ("3+5", 8), ("2+4", 6), pytest.param("6 * 9", 42, marks=pytest.mark.xfail), ]) def test_eval(test_input, expected): print("-------开始用例------")> assert eval(test_input) == expectedE assert 54 == 42
test_demo.py:10: AssertionError
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标记为失败的用例，预期结果是失败，实际运行也是失败，显示 xfailed
参数组合
若要获得多个参数化参数的所有组合，可以堆叠参数化装饰器
import pytest@pytest.mark.parametrize("x", [0, 1])@pytest.mark.parametrize("y", [2, 3])def test_foo(x, y): print("测试数据组合：x->%s, y->%s" % (x, y))
if __name__ == "__main__": pytest.main(["-s", "test_demo.py"])
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运行结果:
============================= test session starts =============================collecting ... collected 4 items
test_demo.py::test_foo[2-0] PASSED [ 25%]测试数据组合：x->0, y->2
test_demo.py::test_foo[2-1] PASSED [ 50%]测试数据组合：x->1, y->2
test_demo.py::test_foo[3-0] PASSED [ 75%]测试数据组合：x->0, y->3
test_demo.py::test_foo[3-1] PASSED [100%]测试数据组合：x->1, y->3
============================== 4 passed in 0.03s ==============================
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这将运行测试，参数设置为 x＝0／y＝2，x＝1／y＝2，x＝0／y＝3，x＝1／y＝3 组合参数。
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