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Pytest (6) -fixture (Firmware)

2022-07-03 02:41:00 【Here is a blank sheet of paper for you】

What is firmware

Fixture Translated into Chinese means firmware . It's actually some functions , Will execute the test method / Before testing the function （ Or after ） Load and run them , Common examples are the initial connection of the database before the interface is requested , And closing the database after the request .

We were APP UI Automation series Has been introduced in unittest Relevant test firmware , Such as setup、teardown etc. . and pytest It provides more functions Fixture, Used to implement setup、teardown function .

Define the way

Use @pytest.fixture() Define , A simple example is as follows ：

import pytest

@pytest.fixture()
def before():
    print(" Connect to database ")

Call mode

Call single fixture function

Mode one , Use fixture Function name as argument

import pytest

@pytest.fixture()
def before():
    print(" Connect to database ")


#  call before
def test_01(before):
    print(" perform test_01")

Mode two , Use @pytest.mark.usefixtures('fixture Function name ') Decorator

import pytest

@pytest.fixture()
def before():
    print(" Connect to database ")

#  call before
@pytest.mark.usefixtures('before')
def test_01():
    print(" perform test_01")

Mode three , Use autouse Parameter automatic execution fixture function

import pytest

# fixture Used when defining functions autouse Parameters , This is called automatically by test cases within the scope fixture function 
@pytest.fixture(autouse=True)
def before():
    print(" Connect to database ")

    
#  Automatically call before
def test_01():
    print(" perform test_01")

The results of the three methods are as follows ：

We can see , First executed. fixture function , Then execute the test function .

Call multiple fixture function

import pytest

@pytest.fixture()
def before():
    print(" Connect to database ")

@pytest.fixture()
def before_s():
    print(" Initialization data ")


def test_01(before, before_s):
    print(" perform test_01")

Call multiple fixture Function time , From front to back , therefore test_01() Execute... Before calling before, Re execution before_s.

Yes fixture Function renaming

Definition fixture Function time , You can use name Parameter to rename , Convenient for calling , Examples are as follows ：

import pytest

@pytest.fixture(name='db')
def connect_order_db():
    print(" Connect to database ")


def test_01(db):
    print(" perform test_01")

Use fixture Passing test data

The execution of the fixture After the function , Sometimes it is necessary to fixture Some data obtained in the test function is passed to the test function / The test method , For subsequent execution .

fixture There are two data transfer methods: general transfer and parametric transfer .

Ordinary transmission

Examples are as follows ：

import pytest

@pytest.fixture()
def before():
    print(" Connect to database ")
    return " Successful connection ！"


def test_01(before):
    print(" perform test_01")
    assert before == " Successful connection ！"

Be careful , If customized fixture Function has return value , You need to use the above-mentioned method to obtain fixture Function and pass it into the test function , The return value cannot be obtained in mode 2 .

Parameterized transfer

Yes fixture When a function is parameterized , You need to use parameters params, Parameters are passed in and required request, A simple example is as follows ：

import pytest

test_params = [1, 2, 0]
@pytest.fixture(params=test_params)
def before(request):
    result = request.param
    return result

def test_02(before):
    print(" perform test_02")
    assert before


if __name__ == '__main__':
    pytest.main()

Execution results ：

You can see , Because the called fixture The function is parameterized , Although there is only one test function, it is executed 3 Time .

conftest.py

The above examples are all fixture The function is placed in the test case module , But if many test modules need to reference the same fixture What about functions , It's time to put it in a place named conftest In the module of , such Same level or below The test cases in the can call these custom test cases fixture function .

for example , There is a list of ：

├─testcase
│  │
│  ├─test_module_01
│  │      test_case_1.py
│  │      test_case_2.py
│  │
│  ├─test_module_02
│  │      test_case_3.py

test_module_01 Medium test_case_1.py And test_case_2.py All need to call the same fixture function , Then we just need to test_module_01 New China conftest.py And write this fixture Function , Examples are as follows ：

├─testcase
│  │
│  ├─test_module_01
│  │      conftest.py
│  │      test_case_1.py
│  │      test_case_2.py
│  │
│  ├─test_module_02
│  │      test_case_3.py

conftest.py:

import pytest

@pytest.fixture(autouse=True)
def before():
    print(" Connect to database ")

test_case_1.py：

def test_01():
    print(" perform test_01")

test_case_2.py：

def test_02():
    print(" perform test_02")

such , When the two test cases are called, they will be automatically executed first conftest.py Medium before() function .

hypothesis test_module_02 Medium test_case_3.py You also need to call this before() function , Then at this time, we need to be on the upper layer, that is testcase New China conftest.py And write this before() function , Can be in test_case_3.py Call in , as follows ：

├─testcase
│  │  conftest.py
│  │
│  ├─test_module_01
│  │      conftest.py
│  │      test_case_1.py
│  │      test_case_2.py
│  │
│  ├─test_module_02
│  │      test_case_3.py

conftest.py Only for At the same level or following Test modules in the directory , And we need Be careful , When following There is another in the hierarchy conftest.py, Then the following levels will be determined by another conftest.py File take over .

Scope

pytest Of fixture The scope is divided into session、module、class、function Four levels . In defining fixture Function through scope Parameter specifies the scope of action , The default is function.

session, Execute once per session
module, Once per test module
class, Execute once per test class
function, Once per test method

Be careful , For separately defined test functions ,class、function It all works , You can see from the following example .

The test directory structure is as follows ：

├─apiAutoTest
│  │  run.py
│  │
│  ├─testcase
│  │  │  conftest.py
│  │  │
│  │  ├─test_module_02
│  │  │  │  conftest.py
│  │  │  │  test_case_3.py
│  │  │  │  test_case_4.py

among conftest.py The code is as follows ：

import pytest

@pytest.fixture(scope="session", autouse=True)
def session_fixture():
    print(" This is a function of session Of fixture")

@pytest.fixture(scope="module", autouse=True)
def module_fixture():
    print(" This is a function of module Of fixture")

@pytest.fixture(scope="class", autouse=True)
def class_fixture():
    print(" This is a function of class Of fixture")

@pytest.fixture(scope="function", autouse=True)
def function_fixture():
    print(" This is a function of function Of fixture")

test_case_3.py The code is as follows ：

import pytest

class TestOrder:

    def test_a(self):
        print("test_a")
        
    def test_b(self):
        print("test_b")

def test_c():
    print("test_c")

test_case_4.py The code is as follows ：

def test_e():
    print("test_e")

run.py The code is as follows ：

import pytest

if __name__ == '__main__':
    pytest.main(["-s"])

function run.py, give the result as follows ：

collected 4 items

testcase\test_module_02\test_case_3.py 
 This is a function of session Of fixture
 This is a function of module Of fixture
 This is a function of class Of fixture
 This is a function of function Of fixture
test_a
. This is a function of function Of fixture
test_b
. This is a function of class Of fixture
 This is a function of function Of fixture
test_c
.
testcase\test_module_02\test_case_4.py 
 This is a function of module Of fixture
 This is a function of class Of fixture
 This is a function of function Of fixture
test_e
.

============================== 4 passed in 0.04s ==============================

It can be seen from the result that ：

Act on session Of fixture The function is called once before all test cases are executed.
Act on module Of fixture The function is called once before each test module is executed.
Act on class Of fixture The function is called once before each test class is executed.
Act on function Of fixture Function in each test method / The test function was called once before it was executed.

Be careful , In the defined test function （ Such as test_c()、test_e()） Before execution, it will also call scope=class Of fixture function .