What is the difference between a white box, black box, and gray box testing?

When you develop a web application, before hosting to the web, testing is very important to prevent the hackers. There are three types of tests, Black, gray and white box tests which are conducted to ensure that an attacker cannot reach your application code.

White Box (or glass box) testing

• White Box (or glass box) testing is the process of giving input code to the system and checking how the system processes it how the output is generated using that code. This is the test where the team tests the internal logic of the code written.
• It is the process of checking how the system processes input to give a suitable output by giving it the required input.

• It involves testing a system with full access to source code and other architecture documents. This testing reveals bugs and vulnerabilities as quickly as possible. In comparison to an authentic trial and error method, this white box testing is way quicker.
• By exactly knowing what to test, more testing coverage is ensured. This type of testing involves testing of the application. It needs knowledge of code and test cases chosen if the system is implemented as expected it is verified.
• It is basically checking whether the given code gives out expected results.

E.g. In electrical appliances the internal circuit testing.

Black Box testing

• Black box testing is a method of testing where the input is given to the system and the output is checked, no matter how it was generated. It is done at an outer level.
• It can be done without any knowledge of the system as of how it works. However, it is a less good way of testing when compared to white box testing as no internal knowledge is concerned it this. Any glitch cannot be corrected as there is no architectural or code knowledge involved.
• The system is tested by the team just for the suitable output for the given input. Hence the application is tested here.

Gray Box Testing

• This is the combination of both white box and black box testing.
• In this type of testing the tester has limited knowledge of the system and the internal applications. Just the output is checked as per the given inputs.
• Gray Box testing is a combination of White Box and Glass Box Testing. In this Gray box testing, the tester need not have the knowledge about the internal working of the software.
• Only the output, the process of how the output has arrived is tested in this method.