Pytest Series (2) - assert the use of assertions in detail

If you want to learn from scratch Pytest, you can look at this series of articles Oh!

https://www.cnblogs.com/poloyy/category/1690628.html

 

Foreword

• Unlike unittest, pytest using python comes to assert assert keyword
• assert keyword followed by one expression can, as long as the final result of the expression is True, then the assertion by the successful implementation of the use case, or else fails use case

 

assert small chestnuts

I want to output some tips after throwing an exception after executing it easy to see what is the reason the

# Abnormality information 
DEF F ():
     return . 3 

DEF test_function (): 
    a = F ()
     Assert a% 2 == 0, " determines a is an even number, a current value:% S " % a

Results of the

 

Common assertions

pytest assertion which is actually inside the python assert assertion methods commonly used are the following

• assert xx: xx determination is true
• assert not xx: xx judge is not true
• assert a in b: b comprising a Analyzing
• assert a == b: a = b Analyzing
• assert a = b:! a = b Analyzing

 

Abnormal assertion

Pytest.raises can be used as a context manager, it can be acquired when an exception is thrown to the corresponding abnormal category

# Assertion abnormal 
DEF test_zero_division (): 
    with pytest.raises (ZeroDivisionError):
         1/0

 

Assertion scene: the assertion that it is not expected to throw exceptions you want

Code execution: 1/0

Expected result: cast exception is ZeroDivisionError: division by zero

How asserted: usually asserted type and value of the abnormal values

DETAILED DESCRIPTION: Here exception type is 1/0 ZeroDivisionError, abnormal values divisionby zero value

# Assert detailed abnormal 
DEF test_zero_division_long (): 
    with pytest.raises (ZeroDivisionError) AS excinfo:
         1/ 0 

    # assertion exception type of the type 
    the Assert excinfo.type == ZeroDivisionError
     # assertion abnormal value value 
    the Assert  " Division by ZERO "  in str (excinfo. value)

excinfo  : it is an example of the abnormality information

The main properties:  .type  ,  .Value  ,  .traceback 

Note: The assertion type when abnormal type is unquoted, the assertion value when the value to be transferred str