小编点评

## Summary of test cases This document summarizes the purpose and functionality of different pytest plugins for asserting multiple conditions: **1. `pytest.assume`:** * This plugin allows defining a single assumption for a set of tests. * It ignores subsequent assumptions and only raises an error if the first assumption fails. * It can be used with a single `assert` statement or multiple `pytest.assume` calls. **2. `pytest.assume(condition)`:** * This plugin allows explicitly asserting a condition before executing subsequent tests. * It allows more control and debugging capabilities compared to `pytest.assume`. * It can be used in conjunction with `assert` statements or `pytest.skip`. **3. `pytest.assume` context manager:** * This plugin allows defining assumptions within a context manager. * It allows defining and executing multiple assumptions within a single block. * It can be used to simplify and organize multiple assert statements. **4. `pytest.assume` with `with` block:** * This plugin allows defining assumptions within a `with` block. * It allows testing specific scenarios and controlling the flow of execution. * It can be used to verify specific conditions and avoid unwanted execution of other tests. **5. `pytest.assume` with multiple `assert` statements:** * This plugin allows defining multiple assumptions within a single `assert` statement. * It is suitable when verifying various conditions within a single unit test. * It can be used with different assertion functions like `assert`, `assert_equal`, and `assert_not`. **6. `pytest.assume` with nested `assert` statements:** * This plugin allows nesting assumptions within other assumptions. * It allows verifying complex conditional scenarios with multiple layers of assumptions. * It can be used to control the execution flow and ensure specific conditions are met. **Note:** * These plugins can be used together within the same test case. * It is recommended to use context managers for defining and executing assumptions. * Always specify the assertion function used with `assert` statements within the `with` block.

正文

Pytest插件pytest-assume多重断言

背景

import pytest


def test_assume1():
    assert 1 == 2
    print('hello')
    assert 2 == 3


if __name__ == '__main__':
    pytest.main(['-sv', __file__])

• 这样的代码运行的时候并不会打印hello
• 同样后面的assert 2==3也不会去操作
• 而实际测试的时候我们经常性的会遇到要去多重断言的情况

安装

pip install pytest-assume

pip install git+https://github.com/astraw38/pytest-assume.git  

介绍

https://pypi.org/project/pytest-assume/ 不要看，啥都没有

https://github.com/astraw38/pytest-assume github上也就讲了几句

• A pytest plugin that allows multiple failures per test

用法一、assume

import pytest


def test_assume2():
    pytest.assume( 1 == 2 )
    print('hello')
    pytest.assume( 2 == 3)

if __name__ == '__main__':
    pytest.main(['-sv', __file__])

• 输出

demo_assume.py::test_assume2 hello
FAILED
...

E               demo_assume.py:16: AssumptionFailure
E               >>	pytest.assume( 1 == 2 )
E               AssertionError: assert False
E               
E               demo_assume.py:18: AssumptionFailure
E               >>	pytest.assume( 2 == 3)
E               AssertionError: assert False

• 可以看到
  • hello 也输出了
  • assume也断言了第二种

用法二、上下文管理器(推荐)

• 在用法一种隐含了一个小的瑕疵

  import pytest
  
  
  def test_assume3():
      a = 1
      b = 2
      pytest.assume( a == b )
  
  if __name__ == '__main__':
      pytest.main(['-sv', __file__])
  

• 它的输出是

  E               demo_assume.py:18: AssumptionFailure
  E               >>	pytest.assume( a == b )
  E               AssertionError: assert False
  

• 你可以看到，变量的真正的值并没有看到，当然你有很多其他的方法来处理，但能看到显然是更利于你便捷的去定位的

• 这个时候可以用另外一种做法：上下文管理器

  import pytest
  
  
  def test_assume4():
      a = 1
      b = 2
      with pytest.assume: assert a==b
  
  if __name__ == '__main__':
      pytest.main(['-sv', __file__])
  

• 输出

  E       demo_assume.py:18: AssumptionFailure
  E       >>	with pytest.assume: assert a==b
  E       AssertionError: assert 1 == 2
  

  • 你可以清晰的看到变量的值了

• 注意，在这种写法中，你要写assert，而第一种写法中你不需要用到assert的

---

• 在with的写法中，你可以在一个块中assert多个断言内容，但这样是不推荐的

  import pytest
  
  
  def test_assume5():
      a = 1
      b = 2
      with pytest.assume:
          assert a==b
          assert 1==2
          assert 3==3
  
  if __name__ == '__main__':
      pytest.main(['-sv', __file__])
  

• 输出：最终你就看到了第二个错误的信息，a==b的断言被你忽略掉了

  E           demo_assume.py:21: AssumptionFailure
  E           >>	assert 3==3
  E           AssertionError: assert 1 == 2
  

• 你应该这样写

  import pytest
  
  
  def test_assume6():
      a = 1
      b = 2
      with pytest.assume:     assert a == b
      with pytest.assume:     assert 1 == 2
      with pytest.assume:     assert 3 == 3
  
  
  if __name__ == '__main__':
      pytest.main(['-sv', __file__])
  

• 输出

         with pytest.assume:     assert a == b
  >       with pytest.assume:     assert 1 == 2
  E       pytest_assume.plugin.FailedAssumption: 
  E       2 Failed Assumptions:
  E       
  E       demo_assume.py:18: AssumptionFailure
  E       >>	with pytest.assume:     assert a == b
  E       AssertionError: assert 1 == 2
  E       
  E       demo_assume.py:19: AssumptionFailure
  E       >>	with pytest.assume:     assert 1 == 2
  E       AssertionError: assert 1 == 2