You have a lot of mistakes pls follow these
In the test brackets you should have test('#isDefined, #isUndefined',
And you have written the whole code wrong but I can’t explain I’m going to give the solution test('#isDefined, #isUndefined', function(){ assert.fail( null, 'null is not undefined'); assert.fail( undefined, 'undefined IS undefined'); assert.fail( 'hello', 'a string is not undefined' ); });
But no worries you can try next time
It’s not immediately clear when you do this the first time, but you are just completing the tests with the correct assertion methods. For example, in the first set of tests
test('#isNull, #isNotNull', function(){
assert.fail(null, 'this is an optional error description - e.g. null is null');
assert.fail( 1, '1 is not null');
});
you are using the isNull() and isNotNull() assertion methods to make the tests pass. The assertion method fail() will always fail. So to make the first test pass, since the first argument is null, you want to use the isNull() method like
assert.isNull(null, 'this is an optional error description - e.g. null is null');
and the test should pass, since null is null. Likewise, you would use isNotNull() on the second one since 1 is not null, and so on and so forth, replacing fail() with the correct method.
You can read about all the chai assertion methods (and lots more) in the documentation.