Pytest (5) - assertion

Preface

Assertions are an integral part of a complete test case , Use cases only add assertions , Compare the actual results with the expected results , To judge whether it passes .

unittest The framework provides its own assertion method , Such as ：assertEqual、assertTrue、assertIn etc. ,pytest It also has its own way of asserting , That is to use assert To assert that .

assert

pytest Use in python Source Ecology assert Field assertion .

Common assertions

pytest Common assertions are as follows ：

• Judge whether it is equal ,assert Actual( The actual result ) == Expected( Expected results )
• Judge whether it is not equal ,assert Actual != Expected, Other such as >、<、>=、<= Can be used directly .
• Judge xx Is it true ,assert xx
• Judge xx Is it not true ,assert not xx
• Judge b Does it include a,assert a in b
• Judge b It doesn't contain a,assert a not in b

assert The asserted object can be a string 、int、float、list、dict、tuple Any type .

Examples of use

Customize an interface to query all user information , The format of the return parameter is as follows ：

{
    "code": 1000,
    "data": [
        {"id": 1, "username": " Lau Andy ", "sex": 0, "telephone": "12306", "address": " Kowloon, Hong Kong "},
        {"id": 2, "username": " Anita Mui ", "sex": 1, "telephone": "95511", "address": " Huangpu District, Shanghai "},
        {"id": 3, "username": " Danny chan ", "sex": 0, "telephone": "10086", "address": " Haidian District, Beijing "},
    ]
}

The use case assertions are as follows ：

def test_get_all_users():
    ''' Query all user information '''
    url = "http://127.0.0.1:5000/users"
    res = requests.get(url=url).text
    res = json.loads(res)
    #  Whether the assertion is equal 
    assert res['code'] == 1000
    #  Assertion returns results data Is it True（ This is actually to judge whether it is empty ）
    assert res['data']
    
    Andy = {"id": 1, "username": " Lau Andy ", "sex": 0, "telephone": "12306", "address": " Kowloon, Hong Kong "}
    #  Assertion returns results data Whether it contains Andy Lau's information 
    assert Andy in res['data']

Assertion passed ：

Let's modify the script to make the assertion fail , as follows ：

def test_get_all_users():
    ''' Query all user information '''
    url = "http://127.0.0.1:5000/users"
    res = requests.get(url=url).text
    res = json.loads(res)
    #  Whether the assertion is equal 
    assert res['code'] == 1001
    #  Assertion returns results data Is it True（ This is actually to judge whether it is empty ）
    assert not res['data']
    
    Andy = {"id": 1, "username": " Lau Andy ", "sex": 0, "telephone": "12306", "address": " Kowloon, Hong Kong "}
    #  Assertion returns results data Whether it contains Andy Lau's information 
    assert Andy not in res['data']

The operation results are as follows ：

You can see ,code Of Actual by 1000, and Excepted by 1001, So the assertion directly reports an error , Do not continue to execute the following code .

Add exception information to the assertion result

We can assert exceptions , Output some hints , After such an assertion reports an error , It is convenient for us to check the reason .

The customized user information interface can query the information of a user , Write a test script for it as follows ：

def test_get_user():
    ''' Query all user information '''
    url = "http://127.0.0.1:5000/users/1"
    res = requests.get(url=url).text
    res = json.loads(res)
    assert res['code'] == 1000
    assert res['data']['username'] == " Jacky Cheung ", " Judge whether the return is Jacky Cheung , Actual return ：{}".format(res['data']['username'])

The operation results are as follows ：

summary

pytest It can also be used for Exception And Warnning To assert that , But these situations are rarely used in our tests , So don't elaborate too much .