Pytest unit test framework: simple and easy to use parameterization and multiple operation modes

Unit test framework , You are familiar with Unittest、Nose（unittest An extension of ）.Pytest It's unknown , But since I used it , I can't put it down , As it describes itself ：simple powerful testing with Python. Easy to use parameterization and various operation modes , Make the test script simple and clear , Debugging and operation are more convenient .
One 、 A parameterized

For example, we are doing automated testing , When different parameters are passed , Expected return status code by 200. If you use Unittest It is complicated to do this parameterization , and pytest It's a lot easier . stay pytest There is pytest.mark.parametrize Decorator , Easy problem solving . We take the sogo As an example .

Use case description ：

Step one 、 Turn on Sogou search （http://www.sogou.com/）

Step two 、 Input tesla Click the magnifying glass to search

expect ： Return to normal

If you use interfaces , It's equivalent to query Parameters are passed later tesla that will do , The verification status code is 200

If you use interfaces , It's equivalent to query Parameters are passed later tesla that will do , The verification status code is 200

Import requests

Session = requests.session()

url = ‘https://www.sogou.com/web?’

para = {‘query’: ‘tesla’}

r = session.get(url, params=para, verify=False, allow_redirects=False)

assert r.status_code == 200

in fact , If only one search term is passed, the interface is considered normal , Then it is likely to be a big basket . So we may need to pass n Search terms to verify . in other words ,para Medium query In the following content, we need to pass many different search terms . For example, we want to search VR,BITCOIN Wait for more words , What needs to be done ？

This is the time to use pytest There is pytest.mark.parametrize Decorator , The code is as follows 8 That's ok , Just add a decorator outside the method .

Import pytest

Import requests

Session = requests.session()

url = https://www.sogou.com/web?’

search= [‘tesla’,‘VR’,‘BITCOIN’]

@pytest.mark.parametrize(‘test_input’,search)

def test_status_code(test_input):

para = {‘query’:test_input}

r= session.get(url,params=para, verify=False, allow_redirects=False)

assert r.status_code == 200

At this time, some students may ask questions , For multiple parameters, we use for Circulation can also be done , Why use this method . The reason is to use pytest Parameterization of , A parameter passed in is a case, In the above example, we passed in three parameters , Then there are three cases, Which parameter is passed in causing an error , We know at a glance . So what to do ？ We are cmd Running scripts inside , Suppose the script file name is test_sogo_search.py, Place in C Under the plate ：

C:>pytest test_sogo_search.py --html=./result/Report.html

stay pytest What you see in your report is this
Through such a report , You can clearly know which search term is correct , Which search term verification result is wrong . Comparative use for In a circle , It's much clearer . In addition, there is the running time , It can also give additional information .

Two 、 Operation mode

Pytest A variety of operating modes , Make testing and debugging easier , Let's introduce 5 There are many modes used . Before the introduction, I need to remind you , function pytest I will find it when test Files beginning with test The first method or class, Otherwise, you will be prompted that you can't find a running case 了 .
1、 Generate result report after operation （htmlReport）

Operation mode ：

pytest test_case.py --html=./result/test_caseReport.html

effect ：

When a run error occurs , stay report You can intuitively see the cause of the error , Above picture , Expected status_code yes 302, But it is 200, So I made a mistake . Looking at the report, it becomes very easy to locate the problem . And the test results need not be sorted , Just submit the report directly .

2、 Run the specified Case

Code block （test_case.py）

class TestClassOne(object):

def test_one(self):

x = “this”

assert ‘h’ in x

def test_two(self):

x = “hello”

assert hasattr(x, ‘check’)

class TestClassTwo(object):

def test_one(self):

x = “this”

assert ‘h’ in x

def test_two(self):

x = “hello”

assert hasattr(x, ‘check’)

Operation mode ：

Pattern 1：$ pytest test_case.py

Pattern 2：$ pytest test_case.py::TestClassTwo

Pattern 3：$ pytest test_case.py::TestClassTwo::test_one

explain ：

Pattern 1： Directly execute the whole test_case File in all case

Pattern 2： function test_case In file TestClassTwo This class Of the two cases

Pattern 3： function test_case In file TestClassTwo This class Under the test_one

effect ：

When we write more cases when , If you have to run it every time , It's undoubtedly a waste of time , In this simple way, we can easily specify any case Here we go .

Be careful ：

Definition class when , Need to be T start , Otherwise pytest Is not going to run the class Of .

3、 Multi process running cases

pip install pytest-xdist

Operation mode ：

$ pytest tes_case.py -n NUM

effect ：

When case When it reaches a certain amount , The running time will become very long , If you want to shorten the running time of the script , Then you can use it to do .NUM Fill in the number of concurrent processes you want . Speed swish ~ Try it ！

4、 Retry running cases

pip install pytest-rerunfailures

Operation mode ：

$pytest tes_case.py --reruns NUM

effect ：

When doing interface tests , Sometimes 503 Or short-term network fluctuations , Lead to case It will fail , In fact, it is not the result we want , At this time, you can run again case The way , Re execution . How many times to try again , Fill in with you NUM of .

5、 Show print Content

Operation mode ：

$pytest tes_case.py -s

effect ：

When running the test script , In order to debug or want to print something , We'll add some... To the code print Content , But it's running pytest when , These contents will not be displayed . If you bring it -s The mode of operation of , You can see that print The content of will be displayed .

in addition Pytest Multiple operation modes of can be superimposed , for instance , You want to run at the same time 4 Another process wants to print out print The content of , It can be used $pytest test_case.py -s -n 4

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