When {expected} and {actual} are not equal an error message is added to |v:errors| and 1 is returned. Otherwise zero is returned |assert-return|. There is no automatic conversion, the String "4" is different from the Number 4. And the number 4 is different from the Float 4.0. The value of 'ignorecase' is not used here, case always matters. When {msg} is omitted an error in the form "Expected {expected} but got {actual}" is produced. Example: assert_equal('foo', 'bar') Will result in a string to be added to |v:errors|: test.vim line 12: Expected 'foo' but got 'bar' ~ Can also be used as a |method|, the base is passed as the second argument: mylist->assert_equal([1, 2, 3])