What are the strategies for Integration Testing?

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Dharmendra Gaur · Answer

Integration testing is a logical extension of unit testing. In its simplest form two units that have already been tested are combined into a component and the interface between them is tested. A component in this sense refers to an integrated aggregate of more than one unit. In a realistic scenario many units are combined into components which are in turn aggregated into even larger parts of the program. The idea is to test combination's of pieces and eventually expand the process to test your modules with those of other groups. Eventually all the modules making up a process are tested together. Beyond that if the program is composed of more than one process they should be tested in pairs rather than all at once. Integration testing identifies problems that occur when units are combined. By using a test plan that requires you to test each unit and ensure the viability of each before combining units you know that any errors discovered when combining units are likely related to the interface between units. This method reduces the number of possibilities to a far simpler level of analysis. You can do integration testing in a variety of ways but the following are three common strategies: The top-down approach to integration testing requires the highest-level modules be test and integrated first. This allows high-level logic and data flow to be tested early in the process and it tends to minimize the need for drivers. However the need for stubs complicates test management and low-level utilities are tested relatively late in the development cycle. Another disadvantage of top-down integration testing is its poor support for early release of limited functionality. The bottom-up approach requires the lowest-level units be tested and integrated first. These units are frequently referred to as utility modules. By using this approach utility modules are tested early in the development process and the need for stubs is minimized. The downside however is that the need for drivers complicates test management and high-level logic and data flow are tested late. Like the top-down approach the bottom-up approach also provides poor support for early release of limited functionality. The third approach sometimes referred to as the umbrella approach  requires testing along functional data and control-flow paths. First the inputs for functions are integrated in the bottom-up pattern discussed above. The outputs for each function are then integrated in the top-down manner. The primary advantage of this approach is the degree of support for early release of limited functionality. It also helps minimize the need for stubs and drivers. The potential weaknesses of this approach are significant however in that it can be less systematic than the other two approaches leading to the need for more regression testing.

Satyapriya Nayak · Answer

Hi Ankur In Integration Testing individual software modules are integrated logically and tested as a group. A typical software project consists of multiple software modules coded by different programmers. Integration testing focuses on checking data communication amongst these modules. Hence it is also termed as 'I & T' (Integration and Testing) 'String Testing' and sometimes 'Thread Testing'. Need of Integration Testing: Although each software module is unit tested defects still exist for various reasons like A Module in general is designed by an individual software developer who understanding and programming logic may differ from other programmers. Integration testing becomes necessary to verify the software modules work in unity At the time of module development there wide chances of change in requirements by the clients. These new requirements may not be unit tested and hence integration testing becomes necessary. Interfaces of the software modules with the database could be erroneous External Hardware interfaces if any could be erroneous Inadequate exception handling could cause issues. Integration Test Case: Integration Test case differs from other test cases in the sense it focuses mainly on the interfaces & flow of data/information between the modules . Here priority is to be given for the integrating links rather than the unit functions which are already tested. Sample Integration Test Cases for the following scenario:Application has 3 modules say 'Login Page' 'Mail box' and 'Delete mails' and each of them are integrated logically. Here do not concentrate much on the Login Page testing as it's already being done. But check how it's linked to the Mail Box Page. Similarly Mail Box: Check its integration to the Delete Mails Module. Test Case ID Test Case Objective Test Case Description Expected Result 1 Check the interface link between the Login and Mailbox module Enter login credentials and click on the Login button To be directed to the Mail Box 2 Check the interface link between the Mailbox and Delete Mails Module From Mail box select the an email and click delete button Selected email should appear in the Deleted/Trash folder Approaches/Methodologies/Strategies of Integration Testing: The Software Industry uses variety of strategies to execute Integration testing  viz. Big Bang Approach : Incremental Approach: which is further divided into following Top Down Approach Bottom Up Approach Sandwich Approach - Combination of Top Down and Bottom Up Below are the different strategies the way they are executed and their limitations as well advantages. Big Bang Approach: Here all component are integrated together at once  and then tested. Advantages: Convenient for small systems. Disadvantages: Fault Localization is difficult. Given the sheer number of interfaces that need to be tested in this approach some interfaces links to be tested could be missed easily. Since the integration testing can commence only after all the modules are designed testing team will have less time for execution in the testing phase. Since all modules are tested at once high risk critical modulesare not isolated and tested on priority. Peripheral modules which dealwith user interfaces are also not isolated and tested on priority. Incremental Approach: In this approach testing is done by joining two or more modules that are logically related . Then the other related modules are added and tested for the proper functioning. Process continues until all of the modules are joined and tested successfully. This process is carried out by using dummy programs called Stubs and Drivers . Stubs and Drivers do not implement the entire programming logic of the software module but just simulate data communication with the calling module. Stub : Is called by the Module under Test. Driver : Calls the Module to be tested. Incremental Approach in turn is carried out by two different Methods: Bottom Up Top Down Bottom up Integration In the bottom up strategy each module at lower levels is tested with higher modules until all modules are tested. It takes help of Drivers for testing Diagrammatic Representation : Advantages: Fault localization is easier. No time is wasted waiting for all modules to be developed unlike Big-bang approach Disadvantages: Critical modules (at the top level of software architecture) which control the flow of application are tested last and may be prone to defects. Early prototype is not possible Top down Integration: In Top to down approach testing takes place from top to down following the control flow of the software system. Takes help of stubs for testing. Diagrammatic Representation: Advantages: Fault Localization is easier. Possibility to obtain an early prototype. Critical Modules are tested on priority; major design flaws could be found and fixed first. Disadvantages: Needs many Stubs. Modules at lower level are tested inadequately. Integration Testing Procedure The integration test procedure irrespective of the test strategies (discussed above): Prepare the Integration Test Plan Design the Test Scenarios Cases and Scripts. Executing the test Cases followed by reporting the defects. Tracking & re-testing the defects. Steps 3 and 4 are repeated until the completion of Integration is successfully. Brief Description of Integration Test Plans: It includes following attributes: Methods/Approaches to test (as discussed above). Scopes and Out of Scopes Items of Integration Testing. Roles and Responsibilities. Pre-requisites for Integration testing. Testing environment. Risk and Mitigation Plans. Entry and Exit Criteria. Entry and Exit Criteria to Integration testing phase in any software development model Entry Criteria: Unit Tested Components/Modules All High prioritized bugs fixed and closed All Modules to be code completed and integrated successfully. Integration test Plan test case scenarios to be signed off and documented. Required Test Environment to be set up for Integration testing Exit Criteria: Successful Testing of Integrated Application. Executed Test Cases are documented All High prioritized bugs fixed and closed Technical documents to be submitted followed by release Notes. Best Practices/ Guidelines for Integration Testing First determine the Integration Test Strategy that could be adopted and later prepare the test cases and test data accordingly. Study the Architecture design of the Application and identify the Critical Modules. These need to be tested on priority. Obtain the interface designs from the Architectural team and create test cases to verify all of the interfaces in detail. Interface to database/external hardware/software application must be tested in detail. After the test cases it's the test data which plays the critical role. Always have the mock data prepared prior to executing. Do not select test data while executing the test cases. Please refer the below link http://www.guru99.com/integration-testing.html Thanks

guru patil · Answer

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable{mso-style-name:Table Normal;mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-parent:;mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin:0in;mso-para-margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:10.0pt;font-family:Times New Roman;mso-ansi-language:#0400;mso-fareast-language:#0400;mso-bidi-language:#0400;} 1) Understand the application thoroughly i.e understand how each and every feature works. Also understand how each and every feature are related or linked to each other. 2) Identify all possible scenarios 3) Prioritize all the scenarios for execution 4) Test all the scenarios 5) If you find defects communicate defect report to developers 6) Do positive and negative integration testing.