pytest学习笔记（三）

接着上一篇的内容，这里主要讲下参数化，pytest很好的支持了测试函数中变量的参数化

一、pytest的参数化

1、通过命令行来实现参数化

文档中给了一个简单的例子，

test_compute.py 的测试函数如下：

# content of test_compute.py
def test_compute(param1):
    assert param1 < 4

在conftest.py中添加两个函数，一个是添加参数，一个是根据参数生成测试

# content of conftest.py
def pytest_addoption(parser):
    parser.addoption("--all", action="store_true",help="run all combinations")

def pytest_generate_tests(metafunc):
    if 'param1' in metafunc.fixturenames:
        if metafunc.config.option.all:
            end = 5
        else:
            end = 2
        metafunc.parametrize("param1", range(end))        

通过在命令行添加--all的option来实现参数化，执行py.test -q test_compute.py 会发现只有2个case，而执行 py.test -q test_compute.py --all 会执行5个case

2、不同test IDs的参数化

在pytest会为每一组参数集合建立一个ID，可以试用-k来select匹配的名字子串，所以可以为不同的测试数据建立ID来区分不同的case，这个是经常使用的变量参数化，注意pytest.mark.parametrize（）的括号中的顺序，(变量名称，对应的(参数化元组)的数组，ID的数组) , 这样很好的解决了代码重复编写，减少了维护，可以很好的实现数据与代码想分离

# content of test_time.py
import pytest
from datetime import datetime, timedelta
testdata = [
(datetime(2001, 12, 12), datetime(2001, 12, 11), timedelta(1)),
(datetime(2001, 12, 11), datetime(2001, 12, 12), timedelta(-1)),
]
@pytest.mark.parametrize("a,b,expected", testdata)
def test_timedistance_v0(a, b, expected):
    diff = a - b
    assert diff == expected
@pytest.mark.parametrize("a,b,expected", testdata, ids=["forward", "backward"])
def test_timedistance_v1(a, b, expected):
    diff = a - b
    assert diff == expected

3、重要的资源参数化，这里面给了个case，是关于db的，觉得没太多可说的，就是一个简单的工厂，上代码了

# content of conftest.py
import pytest
def pytest_generate_tests(metafunc):
    if 'db' in metafunc.fixturenames:
        metafunc.parametrize("db", ['d1', 'd2'], indirect=True)
class DB1:
    "one database object"
class DB2:
    "alternative database object"
@pytest.fixture
def db(request):
    if request.param == "d1":
        return DB1()
    elif request.param == "d2":
        return DB2()
    else:
        raise ValueError("invalid internal test config")

4、通过类来实现测试函数的参数化，这个还是很有意义的，自己理解下吧，没什么难度

# content of ./test_parametrize.py
import pytest
def pytest_generate_tests(metafunc):
    # called once per each test function
    funcarglist = metafunc.cls.params[metafunc.function.__name__]
    argnames = list(funcarglist[0])
    metafunc.parametrize(argnames, [[funcargs[name] for name in argnames] for funcargs in funcarglist])
class TestClass:
    # a map specifying multiple argument sets for a test method
    params = {
        'test_equals': [dict(a=1, b=2), dict(a=3, b=3), ],
        'test_zerodivision': [dict(a=1, b=0), ],
    }
　　def test_equals(self, a, b):
    　　assert a == b
　　def test_zerodivision(self, a, b):
    　　pytest.raises(ZeroDivisionError, "a/b")

5、通过multiple fixtures来实现间接的参数化，文档中给了使用不同版本的python编译器的代码，有需求的自己看下吧

"""
module containing a parametrized tests testing cross-python
serialization via the pickle module.
"""
import py
import pytest
import _pytest._code
pythonlist = ['python2.6', 'python2.7', 'python3.3']
@pytest.fixture(params=pythonlist)
def python1(request, tmpdir):
    picklefile = tmpdir.join("data.pickle")
    return Python(request.param, picklefile)
@pytest.fixture(params=pythonlist)
def python2(request, python1):
    return Python(request.param, python1.picklefile)
class Python:
    def __init__(self, version, picklefile):
        self.pythonpath = py.path.local.sysfind(version)
        if not self.pythonpath:
            pytest.skip("%r not found" % (version,))
        self.picklefile = picklefile
    def dumps(self, obj):
        dumpfile = self.picklefile.dirpath("dump.py")
        dumpfile.write(_pytest._code.Source("""
            import pickle
            f = open(%r, 'wb')
            s = pickle.dump(%r, f, protocol=2)
            f.close()
        """ % (str(self.picklefile), obj)))
        py.process.cmdexec("%s %s" % (self.pythonpath, dumpfile))
    def load_and_is_true(self, expression):
        loadfile = self.picklefile.dirpath("load.py")
        loadfile.write(_pytest._code.Source("""
            import pickle
            f = open(%r, 'rb')
            obj = pickle.load(f)
            f.close()
            res = eval(%r)
            if not res:
            raise SystemExit(1)
            """ % (str(self.picklefile), expression)))
        print (loadfile)
        py.process.cmdexec("%s %s" %(self.pythonpath, loadfile))
@pytest.mark.parametrize("obj", [42, {}, {1:3},])
def test_basic_objects(python1, python2, obj):
    python1.dumps(obj)
    python2.load_and_is_true("obj == %s" % obj)

二、使用自定义的markers

1、自定义一个mark，如下，然后 py.test -v -m webtest 只运行标记了webtest的函数， py.test -v -m "not webtest"  来运行未标记webtest的

# content of test_server.py
import pytest
@pytest.mark.webtest
def test_send_http():
    pass # perform some webtest test for your app
def test_something_quick():
    pass
def test_another():
    pass
class TestClass:
    def test_method(self):
        pass

2、还可以通过-v 指定的函数ID， py.test -v test_server.py::TestClass::test_method 来运行指定的函数

3、使用-k 来匹配名字子串， py.test -v -k http ， py.test -k "not send_http" -v

4、在pytest.ini中注册markers

# content of pytest.ini
[pytest]
markers =
    webtest: mark a test as a webtest.
    addopts = --pyargs

好了，就这么多吧，下面的一些关于mocking的，有时间再来写