def test_empty_s():
assert delete_all("", "what") == ""
def test_except():
with pytest.raises(ValueError):
delete_all(1, 2)
def test_simple_case():
assert delete_all("This is AAAstring and this is AABstring",
"AAA") == "This is string and this is AABstring"
def test_multiple_case():
assert delete_all("This is AAAstring and this is also AAAstring",
"AAA") == "This is string and this is also string"
def test_empty_what():
assert delete_all("This should stay untouched!",
"") == "This should stay untouched!"