Essential Integration Testing Checklist PDF for Reliable Software Delivery
                     Integration Testing 
Checklist
Table of Contents
1. Introduction
2. What is Integration Testing?
3. Why is Integration Testing Important?
4. When is Integration Testing Performed?
5. 1. Pre-Integration Checklist
6. 2. Integration Test Planning Checklist
7. 3. Test Execution & Monitoring Checklist
8. Common Pitfalls to Avoid
9. Bonus Section (Optional)
10. Final Notes
Introduction
If you're about to begin integration testing, this checklist will guide you step by 
step — from setting up your environment to validating module interactions — 
so you can catch issues early and ensure smooth system behavior.
What is Integration Testing?
Integration Testing is a fundamental software testing technique where 
individual software modules—already tested in isolation through unit testing—
are combined and tested as a group. The goal is to verify that these integrated 
components work together correctly and communicate as expected. Instead of 
focusing on whether each module works on its own, integration testing checks 
whether they work together to perform complete workflows.
In modern applications—especially those built with microservices, APIs, or 
distributed systems—this phase is critical, as modules often interact across 
boundaries such as networks or third-party services.
Why is Integration Testing Important?
Integration testing is vital because most real-world issues in software don’t 
arise from isolated components failing—they result from the way components 
interact. While unit tests are great for validating individual pieces of logic, they 
can’t catch problems like:
● Incorrect data passed between modules
● Misconfigured APIs
● Incompatible data structures
● Timing and synchronization issues in concurrent components
● Exceptions not being handled properly during inter-module calls
For example, an API may expect a date in YYYY-MM-DD format, but a frontend 
module may send it as MM/DD/YYYY. Unit tests would pass on both sides 
individually, but integration testing would expose the failure when the actual 
communication happens.
Without integration testing, these types of bugs often slip through the cracks 
and only show up during system testing or even in production—where they're 
more expensive to fix and more damaging to the user experience.
When is Integration Testing Performed?
Integration testing is conducted after unit testing but before system testing in the 
typical software testing lifecycle. Once developers have confirmed that 
individual modules behave correctly in isolation, and those modules are 
considered stable, integration testing begins.
There are a few typical scenarios when integration testing is initiated:
1. After all dependent modules are developed and unit tested
This is the classic approach in monolithic systems or tightly coupled 
architectures.
2. During continuous integration in agile projects
Teams often run automated integration tests every time new code is 
committed, ensuring that modules still work well together with the 
latest changes.
3. After external interfaces are mocked or available
If some services (e.g., payment gateways, third-party APIs) are 
unavailable, stubs or mocks may be used to begin integration testing 
earlier.
4. Before full system testing or user acceptance testing (UAT)
Catching issues in integration earlier helps avoid costly bug 
discovery in later stages.
In short, integration testing should begin as soon as multiple modules are 
ready to interact, and it continues progressively as more pieces of the system 
come together.
1. Pre-Integration Checklist
This checklist ensures that all foundational components and environments are 
properly prepared before starting integration testing. Completing these tasks 
reduces the risk of false failures and environment-related issues during 
execution.
Main Task Subtask Complete Failed Revie N/A
d w
1. Verify unit All individual modules ☐ ☐ ☐ ☐
testing readiness have passed unit 
testing
Major unit-level defects ☐ ☐ ☐ ☐
are resolved
2. Identify modules List all ☐ ☐ ☐ ☐
to be integrated components/modules for 
integration
Validate version ☐ ☐ ☐ ☐
compatibility of modules
3. Document API contracts and ☐ ☐ ☐ ☐
interface contracts schemas are finalized
Input/output parameters ☐ ☐ ☐ ☐
are clearly defined
4. Choose Select approach (Top- ☐ ☐ ☐ ☐
integration strategy Down
/ Bottom-Up / Big 
Bang / Hybrid)
Communicate the ☐ ☐ ☐ ☐
chosen strategy to all 
team members
5. Confirm Ensure APIs, services, or ☐ ☐ ☐ ☐
third-party databases are accessible
dependency 
availability
Mock or stub ☐ ☐ ☐ ☐
unavailable services
6. Prepare Create valid data ☐ ☐ ☐ ☐
integration test reflecting real user 
data scenarios
Include negative, null, ☐ ☐ ☐ ☐
and boundary 
condition data
7. Set up the Environment ☐ ☐ ☐ ☐
integration testing mirrors 
environment staging/productio
n
Required configurations, ☐ ☐ ☐ ☐
databases, and services 
are in place
8. Create Stubs created for ☐ ☐ ☐ ☐
stubs/drivers if missing lower-level 
needed modules
Drivers implemented ☐ ☐ ☐ ☐
for missing upper-
level calls
2. Integration Test Planning Checklist
In this phase, you’ll define what to test, how to test it, and who’s responsible. 
A solid test plan will help you catch integration issues early and avoid 
misalignment between teams.
Main Task Subtask Complete Failed Revie N/A
d w
1. Define test scope Identify modules, ☐ ☐ ☐ ☐
interfaces, and 
interactions to test
Exclude modules not in ☐ ☐ ☐ ☐
scope (e.g., already 
validated via system 
tests)
2. Design Write high-level ☐ ☐ ☐ ☐
integration scenarios for module 
scenarios interactions
Include both direct ☐ ☐ ☐ ☐
and indirect data 
flows
3. Write integration Convert each scenario ☐ ☐ ☐ ☐
test cases into step-by-step test 
cases
Cover happy paths, ☐ ☐ ☐ ☐
edge cases, and 
failure conditions
4. Map test cases to Link each test case to ☐ ☐ ☐ ☐
requirements a user story or 
acceptance criterion
Ensure traceability ☐ ☐ ☐ ☐
for all critical 
interfaces
5. Assign Assign who creates, ☐ ☐ ☐ ☐
responsibilities reviews, and executes 
each test
Ensure QA and Dev ☐ ☐ ☐ ☐
both understand their 
testing ownership
6. Select Choose appropriate ☐ ☐ ☐ ☐
tools/frameworks tools (e.g., Postman, 
Selenium, JUnit)
Set up required ☐ ☐ ☐ ☐
integrations
for automation 
and reporting
7. Define entry and Specify what needs to ☐ ☐ ☐ ☐
exit criteria be ready before you 
begin
Define what success ☐ ☐ ☐ ☐
looks like for 
integration testing
8. Finalize test Align test plan with ☐ ☐ ☐ ☐
schedule the sprint/release 
timeline
Review dates ☐ ☐ ☐ ☐
and milestones 
with 
stakeholders
3. Test Execution & Monitoring Checklist
Once planning is complete, it’s time to execute your tests and monitor how the 
modules behave together. You’ll use this checklist to track actual results, 
monitor failures, and verify data flow.
Main Task Subtask Complete Failed Review
d
1. Execute test Run test cases as per ☐ ☐ ☐ ☐
cases the integration test 
plan
Validate outputs ☐ ☐ ☐ ☐
match expected 
results
2. Log results Record test outcomes in ☐ ☐ ☐ ☐
and failures test management tool
Report defects ☐ ☐ ☐ ☐
with 
screenshots/logs
3. Monitor Review communication ☐ ☐ ☐ ☐
module between 
interactions services/modules 
during test runs
Monitor logs, queues, ☐ ☐ ☐ ☐
and system behavior
4. Track and Retest failed test cases ☐ ☐ ☐ ☐
retest defects after bug fixes
Confirm root cause analysis ☐ ☐ ☐ ☐
is
completed for critical 
defects
5. Maintain Update requirement ☐ ☐ ☐ ☐
traceability traceability matrix 
(RTM)
Ensure test coverage ☐ ☐ ☐ ☐
remains aligned with 
scope
Common Pitfalls to Avoid
Even a solid integration test plan can fail if you overlook these key issues. 
Keep this list in mind as you work through your testing process:
● Missing mocks for unavailable modules
If a dependent module or service isn’t ready, make sure you use stubs 
or mocks to simulate its behavior. Skipping this leads to blocked or 
incomplete test coverage.
● Testing in an unstable environment
Always validate your test environment before execution. Inconsistent 
configurations or broken services will give you false results and waste 
debugging time.
● Inadequate test data
You need more than just happy path data. Include edge cases, invalid 
inputs, and empty responses to fully test how integrated modules 
behave under different conditions.
● Not verifying database interactions
Don’t just test the APIs — check that data flows correctly to and from 
your databases, including rollback behavior and data consistency 
Bonuafste rS feaiclutreio cnas e(sO. ptional)
Sample Integration Test Cases
If you’re just getting started or need a reference, here are a few 
examples:
● Verify API A calls Service B with correct payload
● Validate response from Service B triggers database write in Table X
● Simulate failure in Service C and verify fallback logic in Module A
● Check whether logging/tracking is updated when a transaction 
completes
Tool Suggestions
Use these tools to improve the efficiency and automation of your 
integration testing:
● TestGrid– for API testing and chaining requests
● JUnit / TestNG – for Java-based service tests
● Pytest – for Python microservice integration
● Selenium / Cypress – for UI to backend integration flows
● Docker / Kubernetes – to spin up controlled environments
Integration Testing Best Practices
● Start small: integrate two modules at a time
● Automate your regression integration tests
● Keep test data version-controlled
● Make tests part of your CI pipeline
● Use logging to trace integration flows