How to use the pluggy.varnames function in pluggy

def __init__(self, x):
            pass

    class D:
        pass

    class E(object):
        def __init__(self, x):
            pass

    class F(object):
        pass

    assert varnames(C) == ("x",)
    assert varnames(D) == ()
    assert varnames(E) == ("x",)
    assert varnames(F) == ()

def test_varnames_class():
    class C(object):
        def __init__(self, x):
            pass

    class D(object):
        pass

    class E(object):
        def __init__(self, x):
            pass

    class F(object):
        pass

    assert varnames(C) == (("x",), ())
    assert varnames(D) == ((), ())
    assert varnames(E) == (("x",), ())
    assert varnames(F) == ((), ())

def test_varnames():
    def f(x):
        i = 3  # noqa

    class A:
        def f(self, y):
            pass

    class B(object):
        def __call__(self, z):
            pass

    assert varnames(f) == ("x",)
    assert varnames(A().f) == ('y',)
    assert varnames(B()) == ('z',)

def test_varnames():
    def f(x):
        i = 3  # noqa

    class A(object):
        def f(self, y):
            pass

    class B(object):
        def __call__(self, z):
            pass

    assert varnames(f) == (("x",), ())
    assert varnames(A().f) == (('y',), ())
    assert varnames(B()) == (('z',), ())

pass

    class D:
        pass

    class E(object):
        def __init__(self, x):
            pass

    class F(object):
        pass

    assert varnames(C) == ("x",)
    assert varnames(D) == ()
    assert varnames(E) == ("x",)
    assert varnames(F) == ()

def test_varnames():
    def f(x):
        i = 3  # noqa

    class A:
        def f(self, y):
            pass

    class B(object):
        def __call__(self, z):
            pass

    assert varnames(f) == ("x",)
    assert varnames(A().f) == ('y',)
    assert varnames(B()) == ('z',)

def test_varnames():
    def f(x):
        i = 3  # noqa

    class A(object):
        def f(self, y):
            pass

    class B(object):
        def __call__(self, z):
            pass

    assert varnames(f) == (("x",), ())
    assert varnames(A().f) == (('y',), ())
    assert varnames(B()) == (('z',), ())

class C(object):
        def __init__(self, x):
            pass

    class D(object):
        pass

    class E(object):
        def __init__(self, x):
            pass

    class F(object):
        pass

    assert varnames(C) == (("x",), ())
    assert varnames(D) == ((), ())
    assert varnames(E) == (("x",), ())
    assert varnames(F) == ((), ())

def test_varnames():
    def f(x):
        i = 3  # noqa

    class A(object):
        def f(self, y):
            pass

    class B(object):
        def __call__(self, z):
            pass

    assert varnames(f) == (("x",), ())
    assert varnames(A().f) == (('y',), ())
    assert varnames(B()) == (('z',), ())

def test_varnames_default():
    def f(x, y=3):
        pass

    assert varnames(f) == ("x",)