Dive Into the World of Integration Testing Through Examples
Integration testing constitutes a vital stage in software testing, particularly when assessing extensive software comprising numerous heavily linked modules or components. Its objective is to validate the adequate functioning of these interconnected modules and prevent potential glitches.
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When applied to the testing of complex applications using the black box testing strategy, integration testing is a necessity. It facilitates the evaluation of the collective operation of joined modules and verifies that the stipulations are correctly instituted.
Compilation of tutorials included in this series:
Tutorial #1: Understanding Integration Testing (This Tutorial)
Tutorial #2: Exploring Incremental Testing
Tutorial #3: Diving into Component Testing
Tutorial #4: Understanding Continuous Integration
Tutorial #5 Contrasting Unit Testing and Integration
Tutorial #6: Top 10 Tools for Integration Testing
Topics to Be Discussed:
- What is integration testing?
- Why perform Integration Testing?
- Advantages
- Challenges
- Varieties of Integration Testing
- Approaches of Test Integration
- Integration Test for GUI application
- Initiating steps for Integration Tests
- Ingress/Egress Criteria for Integration Testing
- Integration Test Cases
- Is Integration categorized under White box or Black box Technique?
- Instruments for Integration Testing
- Testing System Integration
- Contrast between Integration Testing & System Testing
- Conclusion
Integration Testing: What is it?
The primary goal of integration testing is to assess the combined operation of modules or components already subjected to individual testing. It concentrates on examining the interfaces among these modules and ensures that the connected system runs as anticipated.
The procedure of integration testing encompasses initial individual module testing followed by their gradual consolidation to inspect their overall functioning and confirm the correct establishment of regulations.
Significantly, integration testing is not a single-process activity undertaken at the culmination of the developmental cycle. Instead, it is performed concurrently with development since all the modules might not be ready for testing at once.
The Necessity of Integration Test?
Performing integration testing is essential to confirm the functional correctness of joined modules and guarantee the unhindered data flow among them. Some pivotal reasons that necessitate integration testing include:
- In practical instances, apps are split into smaller modules, each entrusted to unique developers. Integration testing supports in verifying if the logic instituted by each developer meets expectations and produces accurate outputs.
- Transferred data structures and values might get modified across different modules, initiating complications in the following modules. Integration testing helps in identifying and mounting such complications.
- Modules frequently engage with third-party instruments or APIs. Integration testing ensures that the data interchanged with these external entities is accurate, and the subsequent responses fulfill expectations.
- Regular changes in requirements introduce a common hurdle in testing. Integration testing becomes a necessity in such situations, as developers may roll out modifications without comprehensive unit testing.
Benefits
Integration testing brings along several perks, such as:
- Validates the adequate operation of connected modules/components.
- Can be initiated before all modules are made ready, as drivers and stubs can be utilized to replicate the missing modules.
- Aids in identifying errors related to module interfaces.
Obstacles
Integration testing may face various hurdles:
#1) Integration testing necessitates testing of two or more integrated systems for their proper functioning. It mandates comprehensive testing of integration links and the consideration of the overall scenario to assure the correct operation of the integrated system.
#2) Administering integration testing can become intricate due to contributing factors like databases, platforms, and settings.
#3) Melding new systems with existing systems or joining two distinctive existing systems can be challenging, as modifications and testing efforts are essential to assure compatibility and lessen impacts on prevailing systems.
#4) Combining systems formulated by different organizations introduces a significant obstacle, as the outcome of modifications in one system on the other remains unpredictable.
Forms of Integration Testing
Integration testing can be classified into several categories, including the following:
Big Bang Approach:
The Big Bang approach integrates all the modules simultaneously, rather than gradually joining them one by one. The entire system is tested to ascertain its expected behavior. However, in case of any defects, this approach can make it tricky to identify the problematic module.
The Big Bang approach’s advantages include its suitability for smaller systems. However, it becomes challenging to detect the particular faulty module and requires all modules for testing, leaving minimal time for testing critical modules separately.
Approaches to Test Integration
Two fundamental strategies for test integration include:
- Bottom-up approach: This approach initiates with testing the lowest or innermost module of the application and gradually amalgamates higher-level modules. This might necessitate using drivers to mimic upper-level module calls to the lower-level modules. The upside of this approach is early identification of significant faults, but it may delay the recognition of high-level design flaws.
- Top-down approach: This approach commences with testing the topmost module and systematically amalgamates the lower-level modules. It might require using stubs to mimic the lower-level modules’ behavior. The upside of this approach is early identification of high-level design flaws, but it may hold up the identification of significant faults at the lower levels.
A blend of both strategies, termed as “sandwich testing,” can be utilized for more intricate systems, where both approaches are initiated simultaneously.
GUI Application Integration Test
For GUI applications, integration testing assesses the data flow and interactions among the frontend, the middle-layer business logic, third-party integrations, and the backend database.
Example of Integration Testing:
Take the instance of a publicity firm that showcases ads on various websites. The firm requires a system to keep track of the count of ad views and clicks for billing reasons. The system architecture includes:
UI – User Interface module
BL – Business Logic module
VAL – Validation module
CNT – Content module
EN – Engine module
Scheduler – Scheduler module
DB – Database module
In this case, the emphasis would be on validating the flow of data among these modules during integration testing. The data inputted in the UI module is transformed into an XML file, interpreted by the BL, VAL, and CNT modules. The EN module reads the resultant XML file and derives SQL queries executed on the database. The results are reformatted into XML and exhibited through the UI module.
Integration testing would entail validating the correctness of the generated XML files, guaranteeing accurate data transfer among modules, and verifying if the expected behaviors are met.
Additional testing conditions for GUI application integration testing might comprise verifying interface links, confirming menu options, and testing various methods of invoking windows and performing calls among modules.
Initiating Steps for Integration Tests
- Comprehend the application’s architecture.
- Identify the modules and their features.
- Understand how data flows among modules.
- Recognize the application’s entry and exit points.
- Isolate the application for testing purposes.
- Formulate test conditions based on the identified segregation.
- Compose test cases for every test condition.
Integration Testing: Entry/Exit Criteria
Ingress Criteria:
- Endorsement and approval of the integration test plan document.
- Preparation of integration test cases.
- Creation of test data.
- Completion of unit testing for developed modules/components.
- Closure of all critical and high priority defects.
- Setting up of the test environment for integration.
Egress Criteria:
- Execution of all integration test cases.
- No open critical and high priority (P1 & P2) defects.
- Formulation of the test report.
Integration Test Cases
Primarily focusing on interface testing, integrated links, and data transfer amid modules, integration test cases form the phrase. Since the functionality and other aspects of the modules have already been tested during unit testing, integration testing serves to ensure that the integrated modules are operating correctly.
Integration Testing: Is it a White box or a Black box Technique?
Depending on specific circumstances, Integration testing could be seen as both a white box and a black box technique. It qualifies as a black box technique while testing the integration of two web services that fetch and provide data from a database. On the contrary, when integrating a new feature into a website, it is considered a white box technique.
Therefore, it is not strictly classified as either a black box or white box technique.
Tools for Integration Testing
Several resources are available for integration testing, with popular examples such as:
- Rational Integration Tester
- Protractor
- Steam
- TESSY
System Integration Testing
System Integration Testing requires examining the entire integrated system in its entirety. It is executed after unit testing of individual modules or components, with the aim to verify the integrated system’s correct operation.
Contrasting Integration Testing & System Testing
Integration testing emphasizes the assessment of the joint operation of integrated modules or components. It validates whether the connected system functions as projected and doesn’t face problems caused by integrated modules.
Conversely, system testing examines the entire system as a whole. After integrating all individual modules or components, the system is tested to ensure it operates as anticipated without encountering any critical problems.
Closing Remarks
Integration testing holds critical importance in the testing cycle, ensuring the proper operation of interconnected modules and unhindered data transfer among them. It facilitates the early recognition of issues, thus saving cost and effort. By understanding the architecture, identifying the modules, and forming specific test conditions and cases, integration testing can be carried out effectively.
We trust that this instructional tutorial on integration testing gave you valuable insights and examples.