Any junior QA specialist has heard of such concepts as black-box testing, white-box testing, and grey-box testing as well. On the Internet, one can find a lot of useful information about the peculiarities of the first two types. On the contrary, there is little information about grey box testing.

To make it more clear, we analyzed the main principles of the grey-box testing (its advantages and disadvantages), gave examples of situations where it can be used.

[highlight dark=”no”]Grey box testing combines some elements of white box and black box testing. [/highlight]It means that we should analyze these two types before proceeding with grey box testing.

Black Box Testing

Black box testing is a special method of testing the software performance when all the functionality is checked without the analysis of source code. QA engineers make logically understandable test cases based on project specifications.

Advantages of this testing are:

1. It allows quickly finding bugs in the developed functionality of the software;
2. A tester doesn’t need to be a subject matter expert;
3. Testing is performed at the hands of end-user;
4. It is possible to make test cases right after completing the work with specifications.

This kind of testing allows executing the following tests:

• Functional testing;
• Regression testing;
• Usability testing;
• Smoke testing;
• GUI testing.

Nevertheless, this type of testing isn’t enough because there is always a risk to miss major defects.

White Box Testing

White box testing is a special method of software testing which implies that a tester knows the underlying structure and technical features of the software.

This kind of testing consists of a few types of testing used to check the usability of the web product, part of code, or some special program functionality.

Within this testing, you can conduct the following tests:

• Unit tests;
• Integration tests;
• System testing of components;
• Security testing of software performance.

Usually, programmers execute this kind of testing because only a highly professional specialist with technical knowledge can do it.

Basic advantages of this testing method are the following:

• Optimization of program code by searching for hidden bugs;
• Making the automated test cases;
• Use of the most appropriate kind of input data for a better testing process.

Grey Box Testing

Grey box testing is a special kind of software testing with incomplete knowledge of its internal design. QA engineers don’t need to have access to the software source code to conduct this kind of testing.

Specialists make all the tests on the base of simple algorithms, architecture, and other high-level features of product behavior.

There are the following types of grey box tests:

1. Regression tests;
2. Matrix testing;
3. Pattern testing;
4. Software testing with the help of the orthogonal array.

Main advantages of this method are:

• It has some features of the black box and white box. In other words, the tester looks at the object under test from the black box’s side. But on the other hand, he/she has all the necessary data (just like during the white box testing).
• QA specialist can create and use more complicated test scenarios.
• This test allows a programmer to have enough time for bug fixing.
• The programmer interacts with a tester at the primary level. It helps to get rid of unnecessary and odd test cases.

Grey box testing has the following disadvantages:

• The analysis of program code is limited since tester doesn’t have access to the source code.
• There is no way to test all the data input/output flows since it takes a lot of time.
• Also, it can happen that there will be no need in testers (when programmers test their code by themselves with the help of unit tests).

Short Conclusion

So, grey box testing is a popular kind of testing when QA engineers can get full access to the project documentation and they have enough time to prepare test cases with test scenarios.

You can get a maximum benefit from this kind of testing when you test web applications, web services, GUI, and when you perform functional tests focused on system and client security.