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Testing Levels and Types

May 2 2019 , Written by Harry Published on #TESTER

Testing Levels and Types

There are basically three levels of testing i.e. Unit Testing, Integration Testing and System Testing. Various types of testing come under these levels.

 -  Unit Testing

 +  To verify a single program or a section of a single program

 Integration Testing

 + To verify the interaction between system components.

 + Prerequisite: unit testing completed on all components that compose a system.

System Testing

 + To verify and validate behaviors of the entire system against the original system objectives.


    Software testing is a process that identifies the correctness, completeness, and quality of software.

Following is a list of various types of software testing and their definitions in random order:


Formal Testing:

     Performed by test engineers

Informal Testing:

    Performed by the developers

Manual Testing:

    That part of software testing that requires human input, analysis, or evaluation.

Automated Testing:

    Software testing that utilizes a variety of tools to automate the testing process.

    Automated testing still requires a skilled quality assurance professional with knowledge of the automation tools and the software being tested to set up the test cases.

Black box Testing:

    Testing software without any knowledge of the back-end of the system, structure or language of the module being tested.

     Black box test cases are written from a definitive source document, such as a specification or requirements document.

White box Testing:

     Testing in which the software tester has knowledge of the back-end, structure, and language of the software, or at least its purpose.

Unit Testing:

      Unit testing is the process of testing a particular compiled program, i.e., a window, a report, an interface, etc. independently as a stand-alone component/program.

      The types and degrees of unit tests can vary among modified and newly created programs. Unit testing is mostly performed by programmers who are also responsible for the creation of the necessary unit test data.

Incremental Testing:

      Incremental testing is partial testing of an incomplete product. 

      The goal of incremental testing is to provide early feedback to software developers.

System Testing:

       System testing is a form of black box testing.

      The purpose of system testing is to validate an application's accuracy and completeness in performing the functions as designed.

Integration Testing:

       Testing two or more modules or functions together with the intent of finding interface defects between the modules/functions.

System Integration Testing:

        Testing of software components that have been distributed across multiple platforms (e.g., client, web server, application server, and database server) to produce failures caused by system integration defects (i.e. defects involving distribution and back-

Functional Testing

       Verifying that a module functions as stated in the specification and establishing confidence that a program does what it is supposed to do.

End-to-end Testing:

       Similar to system testing - testing a complete application in a situation that mimics real-world use, such as interacting with a database, using network communication, or interacting with other hardware, application, or system.

Sanity Testing:

       Sanity testing is performed whenever cursory testing is sufficient to prove the application is functioning according to specifications.

       This level of testing is a subset of regression testing.

        It normally includes testing basic GUI functionality to demonstrate connectivity to the database, application servers, printers, etc.

Regression Testing:

        Testing with the intent of determining if bug fixes have been successful and have not created any new problems.

Acceptance Testing:

        Testing the system with the intent of confirming the readiness of the product and customer acceptance. Also known as User Acceptance Testing.

Ad-hoc Testing:

        Testing without a formal test plan or outside of a test plan.

        With some projects, this type of testing is carried out as an addition to formal testing.

        Sometimes, if testing occurs very late in the development cycle, this will be the only kind of testing that can be performed – usually done by skilled testers.

         Sometimes ad hoc testing is referred to as exploratory testing.

Configuration Testing:

        Testing to determine how well the product works with a broad range of hardware/peripheral equipment configurations as well as on different operating systems and software.

Load Testing:

       Testing with the intent of determining how well the product handles competition for system resources.

       The competition may come in the form of network traffic, CPU utilization or memory allocation.

Stress Testing:

       Testing is done to evaluate the behavior when the system is pushed beyond the breaking point.

       The goal is to expose the weak links and to determine if the system manages to recover gracefully.

Performance Testing:

       Testing with the intent of determining how efficiently a product handles a variety of events.

       Automated test tools geared specifically to test and fine-tune performance are used most often for this type of testing.

Usability Testing:

       Usability testing is testing for 'user-friendliness'.

       A way to evaluate and measure how users interact with a software product or site.

      Tasks are given to users and observations are made.

Installation Testing:

      Testing with the intent of determining if the product is compatible with a variety of platforms and how easily it installs.

Recovery/Error Testing:

      Testing how well a system recovers from crashes, hardware failures, or other catastrophic problems.

Security Testing:

     Testing of database and network software in order to keep company data and resources secure from mistaken/accidental users, hackers, and other malevolent attackers.

Penetration Testing:

     Penetration testing is testing how well the system is protected against unauthorized internal or external access or willful damage.

     This type of testing usually requires sophisticated testing techniques.

Compatibility Testing:

     Testing used to determine whether other system software components such as browsers, utilities, and competing for software will conflict with the software being tested.

Exploratory Testing:

     Any testing in which the tester dynamically changes what they're doing for test execution, based on information they learn as they're executing their tests.

Comparison Testing:

     Testing that compares software weaknesses and strengths to those of competitors' products.

Alpha Testing:

     Testing after code is mostly complete or contains most of the functionality and prior to reaching customers.

     Sometimes a selected group of users are involved.

     More often this testing will be performed in-house or by an outside testing firm in close cooperation with the software engineering department.

Beta Testing:

     Testing after the product is code complete.

      Betas are often widely distributed or even distributed to the public at large.

Gamma Testing:

     Gamma testing is testing of software that has all the required features, but it did not go through all the in-house quality checks.

Mutation Testing:

     A method to determine to test thoroughness by measuring the extent to which the test cases can discriminate the program from slight variants of the program.

Independent Verification and Validation (IV&V):

     The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner.

     The individual or group doing this work is not part of the group or organization that developed the software.

Pilot Testing:

     Testing that involves the users just before actual release to ensure that users become familiar with the release contents and ultimately accept it.

      Typically involves many users, is conducted over a short period of time and is tightly controlled.

Parallel/Audit Testing:

     Testing where the user reconciles the output of the new system to the output of the current system to verify the new system performs the operations correctly.

Glass Box/Open Box Testing:

     Glass box testing is the same as white box testing.

     It is a testing approach that examines the application's program structure and derives test cases from the application's program logic.

Closed Box Testing:

      Closed box testing is the same as black box testing.

      A type of testing that considers only the functionality of the application.

Bottom-up Testing:

     Bottom-up testing is a technique for integration testing.

     A test engineer creates and uses test drivers for components that have not yet been developed, because, with bottom-up testing, low-level components are tested first.

     The objective of bottom-up testing is to call low-level components first, for testing purposes.

Smoke Testing:

     A random test conducted before the delivery and after complete testing

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