Software Testing - Black Box Testing Strategy

Black box testing is not a type of testing; it instead is a testing strategy, which does not need any knowledge of internal design or code, etc. As the name "black box" suggests, no knowledge of internal logic or code structure is required. The types of testing under this strategy are totally based/focused on the testing for requirements and functionality of the work product/software application. Black box testing is sometimes also called "Opaque Testing", "Functional/Behavioral Testing" and "Closed Box Testing".

The base of the black box testing strategy lies in the selection of appropriate data as per functionality and testing it against the functional specifications in order to check for normal and abnormal behavior of the system. Nowadays, it is becoming common to route the testing work to a third party as the developer of the system knows too much of the internal logic and coding of the system, which makes it unfit to test the application by the developer.

In order to implement black box testing strategy, the tester is needed to be thorough with the requirement specifications of the system and as a user, should know, how the system should behave in response to the particular action.

Various testing types that fall under the black box testing strategy are: functional testing, stress testing, recovery testing, volume testing, user acceptance testing (also known as UAT), system testing, sanity or smoke testing, load testing, usability testing, exploratory testing, ad-hoc testing, alpha testing, beta testing, etc.

These testing types are again divided in two groups: a) Testing in which the user plays a role of tester and b) User is not required.

Testing Methods Where a User is Not Required

Functional Testing
In this type of testing, the software is tested for the functional requirements. The tests are written in order to check if the application behaves as expected.

Stress Testing
The application is tested against heavy load such as complex numerical values, large number of inputs, large number of queries, etc. which checks for the stress/load that the applications can withstand.

Load Testing
The application is tested against heavy loads or inputs such as testing of websites in order to find out at what point the website/application fails or at what point its performance degrades.

Ad-hoc Testing
This type of testing is done without any formal test plan or test case creation. Ad-hoc testing helps in deciding the scope and duration of the other testing methods and it also helps testers in learning the application prior to starting with any other testing.

Exploratory Testing
This testing is similar to the ad-hoc testing and is done in order to learn/explore the application.

Usability Testing
This testing is also called 'Testing for User-Friendliness'. This testing is done if user interface of the application stands an important consideration and needs to be specific for the specific type of user.

Smoke Testing
This type of testing is also called sanity testing and is done in order to check if the application is ready for further major testing and is working properly without failing up to least expected level.

Recovery Testing
Recovery testing is basically done in order to check how fast and better the application can recover against any type of crash or hardware failure, etc. Type or extent of recovery is specified in the requirement specifications.

Volume Testing
Volume testing is done against the efficiency of the application. Huge amount of data is processed through the application (which is being tested) in order to check the extreme limitations of the system.

Testing Where a User is Required

User Acceptance Testing
In this type of testing, the software is handed over to the user in order to find out if the software meets the user expectations and works as it is expected to.

Alpha Testing
In this type of testing, the users are invited at the development center where they use the application and the developers note every particular input or action carried out by the user. Any type of abnormal behavior of the system is noted and rectified by the developers.

Beta Testing
In this type of testing, the software is distributed as a beta version to the users and users test the application at their sites. As the users explore the software, in case if any exception/defect occurs, then that is reported to the developers.