A nice resource to test your password is the website TestYourPassword. In a simply interface you can test your passord and see if a psword can be defined weak, good or strong.
In the main page you can find also a function to generate a new strong password and if you are interested to know how a password is cracked there is nice video to explain how hacker scan a network for weak passwords and crack them.
Link : TestYourPassword
See also the article : How to test your passwords