【开发也是好测试】（三）—pytest fixture scope

导读

　　本文在http://pythontesting.net/framework/pytest/pytest-session-scoped-fixtures/ 文章的基础上，归纳总结fixture的不同scope的区别。

不同scope含义

• session
• module
• class
• function

Scope session 在一次Run或Debug中执行的所有case共享一个session,第一个case开始执行的时候session开始，最后一个case执行结束的时候session结束，这些case可能分布在不同的class或module中。 module 一个.py文件可以看作一个module，其表示的范围指该文件中第一个case到最后一个case之间的范围 class 表示的范围即class的范围 function 表示的范围即function的范围

代码说明

（借用了参考文章中的代码）

conftest.py:

import [e-mail](scope="session")def resource_a(request):    print('In resource_a()')    def resource_a_fin():            print('\nIn resource_a_fin()')    request.addfinalizer(resource_a_fin)@pytest.fixture(scope="module")def resource_b(request, resource_a):    print('In resource_b()')    def resource_b_fin():            print('\nIn resource_b_fin()')    request.addfinalizer(resource_b_fin)@pytest.fixture(scope="function")def resource_c(request, resource_b):    print('In resource_c()')    def resource_c_fin():            print('\nIn resource_c_fin()')    request.addfinalizer(resource_c_fin)# these are just some fun dividiers to make the output pretty# completely unnecessary, I was just playing with autouse [e-mail](scope="function", autouse=True)def divider_function(request):    print('\n        --- function %s() start ---' % request.function.__name__)    def fin():            print('        --- function %s() done ---' % request.function.__name__)    request.addfinalizer(fin)@pytest.fixture(scope="module", autouse=True)def divider_module(request):    print('\n    ------- module %s start ---------' % request.module.__name__)    def fin():            print('    ------- module %s done ---------' % request.module.__name__)    request.addfinalizer(fin)@pytest.fixture(scope="session", autouse=True)def divider_session(request):    print('\n----------- session start ---------------')    def fin():            print('----------- session done ---------------')    request.addfinalizer(fin)

test_one_two.py:

def test_one(resource_c):    print('In test_one()')def test_two(resource_c):    print('\nIn test_two()')

test_three_four.py:

def test_three(resource_c):    print('\nIn test_three()')def test_four(resource_c):    print('\nIn test_four()')

output:

$ py.test -s -v==================================== test session starts ====================================platform darwin -- Python 2.7.5 -- py-1.4.20 -- pytest-2.5.2 -- /usr/bin/pythoncollected 4 items test_one_two.py:1: test_one ----------- session start ---------------    ------- module test_one_two start ---------        --- function test_one() start ---In resource_a()In resource_b()In resource_c()In test_one()PASSEDIn resource_c_fin()        --- function test_one() done ---test_one_two.py:4: test_two         --- function test_two() start ---In resource_c()In test_two()PASSEDIn resource_c_fin()        --- function test_two() done ---In resource_b_fin()    ------- module test_one_two done ---------test_three_four.py:1: test_three     ------- module test_three_four start ---------        --- function test_three() start ---In resource_b()In resource_c()In test_three()PASSEDIn resource_c_fin()        --- function test_three() done ---test_three_four.py:4: test_four         --- function test_four() start ---In resource_c()In test_four()PASSEDIn resource_c_fin()        --- function test_four() done ---In resource_b_fin()    ------- module test_three_four done ---------In resource_a_fin()----------- session done ---------------================================= 4 passed in 0.02 seconds ==================================

在这次执行中一种有4个case,属于同一个session，两个module，4个function，如下表所示

cases session module function test_one test_one_two.py test_one test_two test_one_two.py test_two test_three test_three_four.py test_three test_four test_three_four.py test_four

test_one执行时，session开始，test_one_two.py这个module开始，test_one function开始，test_two执行完成时，function和module范围结束，而直到test_four执行结束时，session才结束。