pytest use case runtime level:
Module level (setup_module/teardown_module) starts at the beginning and ends of the module, and is global (out-of-class, in-function)
Function level (setup_function/teardown_function) is only valid for function use cases (when there are functions outside the class)
The class level (setup_class/teardown_class) runs only once before and after the class (valid in the class, not outside the class)
Method level (setup_method/teardown_method) begins at the beginning and end of the method (in class, not outside class)
setup/teardown in a class runs before and after invoking a method (valid in a class, valid when a function outside a class)

Functional level:

Function pre-set up_function and post-teardown_function are called once before and after each use case starts (function level, multiple calls)

import pytest
def setup_function():
    print("setup_function:Each use case is executed before it starts")
def teardown_function():
    print("teardown_function:Each use case is executed at the end of the use case")
def test_one():
    print("Executing---test_one")
def test_two():
    print("Executing---test_two")
def login():
    print("Executing---test_two")
if __name__ == "__main__":
    pytest.main(["-s","test02.py"])


"C:\Program Files\Python35\python.exe" C:/Users/wangli/PycharmProjects/Test/Test/test02.py
============================= test session starts =============================
platform win32 -- Python 3.5.2, pytest-5.1.2, py-1.8.0, pluggy-0.12.0
rootdir: C:\Users\wangli\PycharmProjects\Test\Test
collected 2 items

test02.py setup_function:Each use case is executed before it starts
//Executing - test_one
.teardown_function:Each use case is executed at the end of the use case
setup_function:Each use case is executed before it starts
//Executing - test_two
.teardown_function:Each use case is executed at the end of the use case


============================== 2 passed in 0.14s ==============================

Process finished with exit code 0

Module pre-setup_module and post-teardown_module are invoked once before and after the whole. py module starts (module level, only once)

import pytest
def setup_module():
    print("setup_module:Whole.py Module starts executing once")
def teardown_module():
    print("teardown_module:Whole.py Module End Execution Once")
def setup_function():
    print("setup_function:Each use case is executed before it starts")
def teardown_function():
    print("teardown_function:Each use case is executed at the end of the use case")
def test_one():
    print("Executing---test_one")
def test_two():
    print("Executing---test_two")
def login_test():
    print("Executing---test_two")
if __name__ == "__main__":
    pytest.main(["-s","test02.py"])


"C:\Program Files\Python35\python.exe" C:/Users/wangli/PycharmProjects/Test/Test/test02.py
============================= test session starts =============================
platform win32 -- Python 3.5.2, pytest-5.1.2, py-1.8.0, pluggy-0.12.0
rootdir: C:\Users\wangli\PycharmProjects\Test\Test
collected 2 items

test02.py setup_module:Whole.py Module starts executing once
setup_function:Each use case is executed before it starts
//Executing - test_one
.teardown_function:Each use case is executed at the end of the use case
setup_function:Each use case is executed before it starts
//Executing - test_two
.teardown_function:Each use case is executed at the end of the use case
teardown_module:Whole.py Module End Execution Once


============================== 2 passed in 0.08s ==============================

Process finished with exit code 0

Class level:

Class pre-setup_class and post-teardown_class are invoked once before and after the beginning of all use cases (class level, only once)

Method pre-setup_method and post-teardown_method are invoked once before and after the beginning of each use case (method level, multiple invocations)

In the class, the pre-set up and post-teardown are invoked once before and after the beginning of each use case (in the method, before and after the method is invoked, many times)

 

setup_class: Before all use cases are executed (class level)

setup_method: Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
Executing - test_one
teardown: Execute after each use case (after calling the method)
teardown_method: Execution at the end of each use case (method level)

setup_method: Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
Executing - test_two
teardown: Execute after each use case (after calling the method)
teardown_method: Execution at the end of each use case (method level)

teardown_class: After all use cases are executed (class level)

 

import pytest


class Test():
    def setup(self):
        print("setup: Execute each use case before it starts (before calling a method)")
    def teardown(self):
        print("teardown: Execution after each use case (after method invocation)")
    def setup_class(self):
        print("setup_class:Before all use cases are executed (class level)")
    def teardown_class(self):
        print("teardown_class:After all use cases are executed (class level)")
    def setup_method(self):
        print("setup_method:Execution before each use case starts (method level)")
    def teardown_method(self):
        print("teardown_method:Execution at the end of each use case (method level)")
    def test_one(self):
        print("Executing---test_one")
    def test_two(self):
        print("Executing---test_two")
    def login_test(self):
        print("Executing---test_two")
    if __name__ == "__main__":
        pytest.main(["-s","test02.py"])


"C:\Program Files\Python35\python.exe" C:/Users/wangli/PycharmProjects/Test/Test/test02.py
============================= test session starts =============================
platform win32 -- Python 3.5.2, pytest-5.1.2, py-1.8.0, pluggy-0.12.0
rootdir: C:\Users\wangli\PycharmProjects\Test\Test
collected 2 items

test02.py setup_class:Before all use cases are executed (class level)
setup_method:Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
//Executing - test_one
.teardown: Execution after each use case (after method invocation)
teardown_method:Execution at the end of each use case (method level)
setup_method:Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
//Executing - test_two
.teardown: Execution after each use case (after method invocation)
teardown_method:Execution at the end of each use case (method level)
teardown_class:After all use cases are executed (class level)


============================== 2 passed in 0.21s ==============================

Process finished with exit code 0

Class and function mix:

setup_module and teardown_module have the highest priority

import pytest
def setup_module():
    print("-setup_module:Whole.py Modules begin to execute once [function]")
def teardown_module():
    print("-teardown_module:Whole.py Module End Execution Once [Function]")
def setup_function():
    print("====setup_function:Every use case executes [functions] before it starts.")
def teardown_function():
    print("====teardown_function:The function is executed after each use case is completed.")
def test_one():
    print("Executing---test_one[Function)")
def test_two():
    print("Executing---test_two[Function)")
def setup():
    print("@@@@@setup: Execution before each use case starts (before calling a method) [Function]")
def teardown():
    print("@@@@@teardown: Execution after each use case (after calling method) [function]")
class Test():
    def setup(self):
        print("setup: Execute each use case before it starts (before calling a method)")
    def teardown(self):
        print("teardown: Execution after each use case (after method invocation)")
    def setup_class(self):
        print("setup_class:Before all use cases are executed (class level)")
    def teardown_class(self):
        print("teardown_class:After all use cases are executed (class level)")
    def setup_method(self):
        print("setup_method:Execution before each use case starts (method level)")
    def teardown_method(self):
        print("teardown_method:Execution at the end of each use case (method level)")
    def test_three(self):
        print("Executing---test_one")
    def test_four(self):
        print("Executing---test_two")
if __name__ == "__main__":
    pytest.main(["-s","test02.py"])



"C:\Program Files\Python35\python.exe" C:/Users/wangli/PycharmProjects/Test/Test/test02.py
============================= test session starts =============================
platform win32 -- Python 3.5.2, pytest-5.1.2, py-1.8.0, pluggy-0.12.0
rootdir: C:\Users\wangli\PycharmProjects\Test\Test
collected 4 items

test02.py -setup_module:Whole.py Modules begin to execute once [function]
====setup_function:Every use case executes [functions] before it starts.
@@@@@setup: Execution before each use case starts (before calling a method) [Function]
//Executing - test_one [function]
.@@@@@teardown: Execution after each use case (after calling method) [function]
====teardown_function:The function is executed after each use case is completed.
====setup_function:Every use case executes [functions] before it starts.
@@@@@setup: Execution before each use case starts (before calling a method) [Function]
//Executing - test_two [function]
.@@@@@teardown: Execution after each use case (after calling method) [function]
====teardown_function:The function is executed after each use case is completed.
setup_class:Before all use cases are executed (class level)
setup_method:Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
//Executing - test_one
.teardown: Execution after each use case (after method invocation)
teardown_method:Execution at the end of each use case (method level)
setup_method:Execution before each use case starts (method level)
setup: Execute each use case before it starts (before calling a method)
//Executing - test_two
.teardown: Execution after each use case (after method invocation)
teardown_method:Execution at the end of each use case (method level)
teardown_class:After all use cases are executed (class level)
-teardown_module:Whole.py Module End Execution Once [Function]


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

Process finished with exit code 0