API testing
API testing at TestLine means checking contracts, data validation and error scenarios for teams that ship backend more often than frontend. I'll write the tests in Postman or RestAssured and plug them into CI.
- Postman
- RestAssured
- SOAP UI
- GraphQL
- JSON Schema
What you get
- Documentation review (OpenAPI, Swagger, WSDL, GraphQL schema) and a list of mismatches
- Postman collections or RestAssured tests with schema validation
- Negative scenarios: invalid data, missing permissions, limits, timeouts
- Runs in CI and an endpoint coverage report
When it's worth it
Backend without tests
Bugs show up only in the UI or at the customer. API tests catch them earlier and cheaper.
Microservices
Several services talk over APIs. Contract tests make sure a change in one doesn't break the others.
Public API for partners
Integrators rely on the documentation. I'll check that the API actually works as described.
Before a version change
A new API version or a database migration. API regression shows what has changed.
How I work
- step 1
Documentation
Spec review and comparison with actual behaviour.
- step 2
Scenarios
Positive, negative and edge cases for the endpoints.
- step 3
Automation
Tests in Postman or RestAssured, test data, CI.
- step 4
Report
Coverage, defects found and recommendations.
Tools
- Postman
- RestAssured
- SOAP UI
- GraphQL
- JSON Schema
Frequently asked questions
Do you also test SOAP and GraphQL?
Yes. I've worked with REST, SOAP (SOAP UI) and GraphQL. For each I use the right validation: JSON Schema, XSD or the GraphQL schema.
Postman or RestAssured?
Postman is quick to start and readable for the whole team. RestAssured works better for large suites maintained alongside Java code.
Do you do API performance testing?
Yes, as a separate service in JMeter. We often combine it with functional tests of the same endpoints.
Got a release in a few weeks?
Describe your project in the form. I'll reply with questions about scope or an initial test plan.