@implementation LoginViewTests

- (void)testPasswordFieldIsNotEmpty {
    LoginViewController *loginView = [[LoginViewController alloc] init];
    //any other setup such as calling -viewDidLoad
    STAssertTrue([loginView.passwordField.text length] > 0, @"The field should not be empty");
    [loginView release]; //unless you're using ARC
}

@end

WHAT IS "STAssertTrue" ?