一、设置标准输出标准错误输出的模式
pytest捕获标准输出标准错误输出的模式主要有以下几种
- pytest :和pytest --capture=fd 模式是一样的,默认的就是pytest --capture=fd 模式
- pytest -s :打开实时输出,关闭Capture Log输出,
- pytest --capture=sys :打开实时输出,Captrue Log只捕获sys.out,sys.err
- pytest --capture=fd :关闭实时输出,Captrue Log捕获所有的标准输出
- pytest --capture=tee-sys :pytest -s 和 pytest --capture=sys的结合,即打开实时输出,同时Captrue Log只捕获sys.out,sys.err
test_demo.py代码如下:
import sys
import os
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
assert 1==2
(1)使用pytest命令执行,此时关闭实时输出,Capture Log捕获所有的标准输出
如下,可以看到Capture Log既有sys.out的输出,也有执行系统命令的输出(执行系统命令的输出不是sys.out,而是文件描述符1)
$ pytest
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
> assert 1==2
E assert 1 == 2
test_demo.py:8: AssertionError
---------------------------- Captured stdout call -----------------------------
in test_demo...
Volume in drive D is work
Volume Serial Number is 84B0-F6B7
Directory of D:\src\blog\tests
2021/12/27 09:38 <DIR> .
2021/12/27 09:38 <DIR> ..
2021/12/24 17:03 <DIR> .pytest_cache
2021/12/27 09:32 16 1
2021/12/23 15:31 168 conftest.py
2021/12/22 17:13 300 pytest.ini
2021/12/16 09:21 1,797 red_blue_ball_ticket.py
2021/12/27 09:38 143 test_demo.py
2021/12/24 15:38 0 __init__.py
2021/12/27 09:38 <DIR> __pycache__
6 File(s) 2,424 bytes
4 Dir(s) 165,265,436,672 bytes free
hello
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - assert 1 == 2
============================== 1 failed in 0.06s ==============================
(2)使用pytest -s 命令,此时打开实时输出,关闭Capture Log输出
如下,只有实时输出,没有Captured stdout call内容
$ pytest -s
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py Volume in drive D is work
Volume Serial Number is 84B0-F6B7
Directory of D:\src\blog\tests
2021/12/27 09:38 <DIR> .
2021/12/27 09:38 <DIR> ..
2021/12/24 17:03 <DIR> .pytest_cache
2021/12/27 09:32 16 1
2021/12/23 15:31 168 conftest.py
2021/12/22 17:13 300 pytest.ini
2021/12/16 09:21 1,797 red_blue_ball_ticket.py
2021/12/27 09:38 143 test_demo.py
2021/12/24 15:38 0 __init__.py
2021/12/27 09:38 <DIR> __pycache__
6 File(s) 2,424 bytes
4 Dir(s) 165,265,436,672 bytes free
in test_demo...
hello
F
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
> assert 1==2
E assert 1 == 2
test_demo.py:8: AssertionError
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - assert 1 == 2
============================== 1 failed in 0.06s ==============================
(3)使用pytest --capture=sys 命令时打开实时输出,Capture Log只输出sys.out的内容
如下,Capture Log中只有sys.out的内容,没有执行系统命令的输出
$ pytest --capture=sys
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py Volume in drive D is work
Volume Serial Number is 84B0-F6B7
Directory of D:\src\blog\tests
2021/12/27 09:38 <DIR> .
2021/12/27 09:38 <DIR> ..
2021/12/24 17:03 <DIR> .pytest_cache
2021/12/27 09:32 16 1
2021/12/23 15:31 168 conftest.py
2021/12/22 17:13 300 pytest.ini
2021/12/16 09:21 1,797 red_blue_ball_ticket.py
2021/12/27 09:38 143 test_demo.py
2021/12/24 15:38 0 __init__.py
2021/12/27 09:38 <DIR> __pycache__
6 File(s) 2,424 bytes
4 Dir(s) 165,265,432,576 bytes free
F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
> assert 1==2
E assert 1 == 2
test_demo.py:8: AssertionError
---------------------------- Captured stdout call -----------------------------
in test_demo...
hello
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - assert 1 == 2
============================== 1 failed in 0.06s ==============================
(4)使用 pytest --capture=fd 命令关闭实时输出,Captrue Log捕获所有的标准输出
$ pytest --capture=fd
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
> assert 1==2
E assert 1 == 2
test_demo.py:8: AssertionError
---------------------------- Captured stdout call -----------------------------
in test_demo...
Volume in drive D is work
Volume Serial Number is 84B0-F6B7
Directory of D:\src\blog\tests
2021/12/27 09:38 <DIR> .
2021/12/27 09:38 <DIR> ..
2021/12/24 17:03 <DIR> .pytest_cache
2021/12/27 09:32 16 1
2021/12/23 15:31 168 conftest.py
2021/12/22 17:13 300 pytest.ini
2021/12/16 09:21 1,797 red_blue_ball_ticket.py
2021/12/27 09:38 143 test_demo.py
2021/12/24 15:38 0 __init__.py
2021/12/27 09:38 <DIR> __pycache__
6 File(s) 2,424 bytes
4 Dir(s) 165,265,432,576 bytes free
hello
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - assert 1 == 2
============================== 1 failed in 0.06s ==============================
(5)使用pytest --capture=tee-sys命令,相当于pytest -s 和 pytest --capture=sys的结合,即打开实时输出,同时Captrue Log只捕获sys.out,sys.err
$ pytest --capture=tee-sys
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py Volume in drive D is work
Volume Serial Number is 84B0-F6B7
Directory of D:\src\blog\tests
2021/12/27 09:38 <DIR> .
2021/12/27 09:38 <DIR> ..
2021/12/24 17:03 <DIR> .pytest_cache
2021/12/27 09:32 16 1
2021/12/23 15:31 168 conftest.py
2021/12/22 17:13 300 pytest.ini
2021/12/16 09:21 1,797 red_blue_ball_ticket.py
2021/12/27 09:38 143 test_demo.py
2021/12/24 15:38 0 __init__.py
2021/12/27 09:38 <DIR> __pycache__
6 File(s) 2,424 bytes
4 Dir(s) 165,265,428,480 bytes free
in test_demo...
hello
F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
def test_demo():
print("in test_demo...")
os.system("dir")
sys.stdout.write("hello\n")
> assert 1==2
E assert 1 == 2
test_demo.py:8: AssertionError
---------------------------- Captured stdout call -----------------------------
in test_demo...
hello
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - assert 1 == 2
============================== 1 failed in 0.06s ==============================
二、在测试函数中捕获标准输出标砖错误输出
用于捕获标准输出有如下四个fixture:capsys, capsysbinary, capfd,和capfdbinary,capsys用于获取sys.out中的内容,当sys.out中的内容为二进制数据时使用capsysbinary,同样,capfd用于获取系统级标准输出,即文件描述符1和2,当数据为二进制时使用和capfdbinary
test_demo.py代码如下:
def test_demo(capsys):
print("hello world")
captured = capsys.readouterr()
assert "hello world hahaha" in captured.out
执行结果如下,可以发现这里能将上面打印语句的内容捕获到,即"hello world\n",这里断言报错主要是通过报错信息查看真是额返回值
$ pytest
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
capsys = <_pytest.capture.CaptureFixture object at 0x00000226B8916D00>
def test_demo(capsys):
print("hello world")
captured = capsys.readouterr()
> assert "hello worldd" in captured.out
E AssertionError: assert 'hello worldd' in 'hello world\n'
E + where 'hello world\n' = CaptureResult(out='hello world\n', err='').out
test_demo.py:5: AssertionError
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - AssertionError: assert 'hello worldd' in 'he...
============================== 1 failed in 0.05s ==============================
还可以设置对指定的内容关闭capture捕获,如下
test_demo.py代码如下,设置当打印hello python的时候关闭捕获
def test_demo(capsys):
print("hello world")
with capsys.disabled():
print("hello python")
print("hello C++")
captured = capsys.readouterr()
assert "hello world" in captured.out
assert "hello C++" in captured.out
assert "hello python" in captured.out
执行结果如下,可以发现,这里确实只捕获了hello world 和hello C++的打印
$ pytest
============================= test session starts =============================
platform win32 -- Python 3.9.7, pytest-6.2.5, py-1.10.0, pluggy-1.0.0
rootdir: D:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collected 1 item
test_demo.py hello python
F [100%]
================================== FAILURES ===================================
__________________________________ test_demo __________________________________
capsys = <_pytest.capture.CaptureFixture object at 0x00000294FFB444C0>
def test_demo(capsys):
print("hello world")
with capsys.disabled():
print("hello python")
print("hello C++")
captured = capsys.readouterr()
assert "hello world" in captured.out
assert "hello C++" in captured.out
> assert "hello python" in captured.out
E AssertionError: assert 'hello python' in 'hello world\nhello C++\n'
E + where 'hello world\nhello C++\n' = CaptureResult(out='hello world\nhello C++\n', err='').out
test_demo.py:10: AssertionError
=========================== short test summary info ===========================
FAILED test_demo.py::test_demo - AssertionError: assert 'hello python' in 'he...
============================== 1 failed in 0.06s ==============================