def test_with_letter_not_from_alphabet():
assert process_reg_exp(reg_exp='ad+', letter='b') == 'ERROR'
def test_basic():
assert process_reg_exp(reg_exp='ab+c.aba.*.bac.+.+*',
letter='a') == 2 # ((a + b)c + a(ba)*(b + ac))*
assert process_reg_exp(reg_exp='acb..bab.c.*.ab.ba.+.+*a.',
letter='c') == 0 # (acb + b(abc)*(ab + ba))*a
def test_extra():
assert process_reg_exp(reg_exp='aab.*.a.a.a.',
letter='a') == 4 # a(ab)*aaa
assert process_reg_exp(reg_exp='aaab..a+.b.b.b.',
letter='a') == 3 # a(aab + a)bbbb
assert process_reg_exp(reg_exp='b1+*', letter='c') == 0 # (b + 1)*
def test_with_one_letter():
assert process_reg_exp(reg_exp='aa.a+', letter='a') == 2 # aa + a
assert process_reg_exp(reg_exp='aa.a+*',
letter='a') == float('inf') # (aa + a)*
def test_with_epsilon():
assert process_reg_exp(reg_exp='a1b+.a.', letter='a') == 2 # a(1 + b)
def test_final_error():
assert process_reg_exp(reg_exp='ab+bc+', letter='a') == 'ERROR'
def test_error_for_two_args():
assert process_reg_exp(reg_exp='a+', letter='a') == 'ERROR'
def test_error_for_one_arg():
assert process_reg_exp(reg_exp='*', letter='a') == 'ERROR'
def test_inf_letter_count():
assert process_reg_exp(reg_exp='a*', letter='a') == float('inf') # a*