Class methods in Python

py_func_test.py

import pytest

class A(object):
  F='FA'
  f1 = lambda: 'f1'
  f2 = lambda self: 'f2'
  def f3(self):
    return 'f3'
  f4 = staticmethod(lambda: 'f4')
  f5 = classmethod(lambda cls: 'f5')
  @staticmethod
  def f6():
    return 'f6'
  @classmethod
  def f7(cls):
    return 'f7/'+cls.F

class B(A):
  F='FB'


def test_f1():
  with pytest.raises(TypeError) as exc:
    A.f1()
  assert exc.value.message == 'unbound method <lambda>() must be called with A instance as first argument (got nothing instead)'

  with pytest.raises(TypeError) as exc:
    A().f1()
  assert exc.value.message == '<lambda>() takes no arguments (1 given)'

def test_f2():
  with pytest.raises(TypeError) as exc:
    A.f2()
  assert exc.value.message == 'unbound method <lambda>() must be called with A instance as first argument (got nothing instead)'
  assert A.f2(A()) == 'f2'
  assert A().f2() == 'f2'

def test_f3():
  with pytest.raises(TypeError) as exc:
    A.f3()
  assert exc.value.message == 'unbound method f3() must be called with A instance as first argument (got nothing instead)'
  assert A.f3(A()) == 'f3'
  assert A().f3() == 'f3'

def test_f4():
  assert A.f4() == 'f4'
  assert A().f4() == 'f4'

def test_f5():
  assert A.f5() == 'f5'
  assert A().f5() == 'f5'

def test_f6():
  assert A.f6() == 'f6'
  assert A().f6() == 'f6'

def test_f7():
  assert A.f7() == 'f7/FA'
  assert A().f7() == 'f7/FA'

def test_B():
  assert B.f2(B()) == 'f2'
  assert B().f2() == 'f2'
  assert B.f3(B()) == 'f3'
  assert B().f3() == 'f3'
  assert B.f4() == 'f4'
  assert B().f4() == 'f4'
  assert B.f5() == 'f5'
  assert B().f5() == 'f5'
  assert B.f6() == 'f6'
  assert B().f6() == 'f6'
  assert B.f7() == 'f7/FB'
  assert B().f7() == 'f7/FB'