为什么我从pytest得到了过多的输出？

Question

使用pytest，当我运行示例测试（创建您的第一个测试）时，我得到了预期的正常输出。当我运行类测试（在一个类中对多个测试进行分组）时，我得到的输出似乎是pytest的调用跟踪。

创建您的第一个测试：

import pytest

def func(x):
    return x + 1

def test_answer():
    assert func(3) == 5

$ pytest
============================= test session starts 
    platform win32 -- Python 3.6.4, pytest-3.9.1, py-1.7.0, pluggy-0.8.0
    rootdir: C:\Users\xxx\dev\tests, inifile:
collected 1 item

mytest.py F                                                         [100%]

================================== FAILURES 
_________________________________ test_answer

    def test_answer():
>       assert func(3) == 5
E       assert 4 == 5
E        +  where 4 = func(3)

mytest.py:7: AssertionError
========================== 1 failed in 0.11 seconds 

现在，当我将测试分组在班级中...

将多个测试分组在一个班级

import pytest

class TestMethod(object):
    def func(x):
        return x + 1

    def test_answer():
        assert func(3) == 5


$ pytest
============================= test session starts =============================
platform win32 -- Python 3.6.4, pytest-3.9.1, py-1.7.0, pluggy-0.8.0
rootdir: C:\Users\xxx\dev\tests, inifile:
collected 1 item

mytest.py F                                                         [100%]

================================== FAILURES ===================================
___________________________ TestMethod.test_answer ____________________________

self = <CallInfo when='call' exception: test_answer() takes 0 positional arguments but 1 was given>
func = <function call_runtest_hook.<locals>.<lambda> at 0x0000000003A0E158>
when = 'call', treat_keyboard_interrupt_as_exception = False

    def __init__(self, func, when, treat_keyboard_interrupt_as_exception=False):
        #: context of invocation: one of "setup", "call",
        #: "teardown", "memocollect"
        self.when = when
        self.start = time()
        try:
>           self.result = func()

..\..\..\lib\site-packages\_pytest\runner.py:206:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
..\..\..\lib\site-packages\_pytest\runner.py:188: in <lambda>
    lambda: ihook(item=item, **kwds),
..\..\..\lib\site-packages\pluggy\hooks.py:284: in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
..\..\..\lib\site-packages\pluggy\manager.py:67: in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
..\..\..\lib\site-packages\pluggy\manager.py:61: in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
..\..\..\lib\site-packages\_pytest\runner.py:116: in pytest_runtest_call
    item.runtest()
..\..\..\lib\site-packages\_pytest\python.py:1435: in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
..\..\..\lib\site-packages\pluggy\hooks.py:284: in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
..\..\..\lib\site-packages\pluggy\manager.py:67: in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
..\..\..\lib\site-packages\pluggy\manager.py:61: in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

pyfuncitem = <Function 'test_answer'>

    @hookimpl(trylast=True)
    def pytest_pyfunc_call(pyfuncitem):
        testfunction = pyfuncitem.obj
        if pyfuncitem._isyieldedfunction():
            testfunction(*pyfuncitem._args)
        else:
            funcargs = pyfuncitem.funcargs
            testargs = {}
            for arg in pyfuncitem._fixtureinfo.argnames:
                testargs[arg] = funcargs[arg]
>           testfunction(**testargs)
E           TypeError: test_answer() takes 0 positional arguments but 1 was given

..\..\..\lib\site-packages\_pytest\python.py:166: TypeError
========================== 1 failed in 0.21 seconds ===========================