Happy-path testing is a type of software testing that uses known input and produces an expected output. Also referred to as golden-path or sunny-day testing, the happy-path approach is tightly scripted. The happy path does not duplicate real-world conditions and verifies only that the required functionality is in place and functions correctly. If valid alternatives exist, the happy path is then identified as the default scenario or the most likely positive alternative featuring no exceptional or error conditions.
Proponents of happy-path testing believe it is possible for developers to focus on an optimal path and create the required functionality while leaving room for bugs in production. However, others strongly disagree. Critics of happy-path testing claim that because happy-path scenarios exclude exceptions and human error, the potential exists for leaving gaps for nulls, incorrect values and various validation errors. Perhaps the strongest argument against happy-path testing is that testing only well-defined UX scenarios can provide an illusion of security that does not exist in real life.
Alternatives to happy path testing
In use case analysis, only one happy path exists, yet there are many additional alternative scenarios that can have valid results. Thinking through various scenarios in advance of software development can save a company money and result in product features that facilitate a better user experience (UX).
The lingo used to describe alternatives to the happy path varies. If, for example, on a login form a user can provide a valid username and password, that is a happy path. On the other hand, if the user mistypes his or her password, that might be called a sad path. One example of a bad path might be entering junk characters in the username field -- a tactic likely to result in an error message.