Rest Api Test Generator

REST API Test Generator

Instructions

Step 1: API Discovery

Ask the user:

1. Which endpoint? (e.g., POST /api/users)
2. Framework? (RestAssured, MockMvc)
3. Authentication? (Bearer token, Basic auth, none)
4. Test environment? (Mock server, local, staging)
5. Request body example and expected response codes

Provide an upfront estimate: 15-20 credits per test scenario.

Step 2: Generate 3 Scenarios Per Batch

Generate exactly 3 test scenarios:

1. Success case (e.g., 201 Created)
2. Validation error (e.g., 400 Bad Request)
3. Business logic error (e.g., 409 Conflict, 404 Not Found)

Use RestAssured template:

@Test
void shouldCreateUser_whenValidRequest() {
    given()
        .contentType(ContentType.JSON)
        .body(validUserRequest)
    .when()
        .post("/api/users")
    .then()
        .statusCode(201)
        .body("id", notNullValue())
        .body("email", equalTo("test@example.com"));
}

STOP after 3 tests. Ask the user to run and confirm responses match.

Step 3: Validation Gate

Validation command:

python scripts/validate_api_tests.py  --base-url http://localhost:8080

Do NOT generate more tests until the user confirms the current batch passes.

Step 4: Fix or Skip (Max 2 Attempts)

If tests fail:

• Attempt 1: Check request/response format, Content-Type, auth token
• Attempt 2: Adjust assertions (nested paths, flexible matchers like hasKey, anyOf)
• After 2 failures: Skip and document expected vs. actual behavior

This usually indicates an API contract mismatch or environment issue -- not something more iterations will fix.

Step 5: Iterate or Finish

After a passing batch, offer:

• Auth tests (401, 403)
• Additional validation scenarios
• Other endpoints
• Stop and produce summary

Step 6: Summary Report

Endpoint: POST /api/users
Tests Generated: N
Status Codes Covered: 201, 400, 401, 409
Skipped: N (with reasons)

Measuring Credit Cost for Your Endpoints

Credit costs vary by Kiro account, model, and endpoint complexity. To get accurate numbers for your environment, follow these steps.

1. Establish your baseline (one-time)

Run the built-in benchmark with a simple GET endpoint:

python track_credits.py benchmark api-simple

This measures the cheapest possible API test on your account (e.g., 0.077 credits/test).

2. Estimate before running on your endpoint

Real API tests get more expensive with nested JSON, auth, and more assertions:

| What makes API tests cost more | How it's scored | |-------------------------------|----------------| | Deeper request/response JSON | +1 for each nesting level | | More response assertions | +1 for every 3 assertions | | Authentication setup | +1 for Bearer, +2 for OAuth flows | | More status codes to test | +1 for every 3 codes |

python track_credits.py estimate \
  --type api \
  --nesting-levels 2 \
  --branches 4 \
  --annotations 3 \
  --tests 3

3. Measure actual cost after running

# Note credit balance before and after, then record:
python track_credits.py add "UsersAPI-POST-3tests"   "3 RestAssured tests, auth"

Your measurements improve future estimates automatically. See ../../../skills-workshop/credit-estimation/CREDIT-ESTIMATION-GUIDE.md for the full guide.

References

• references/examples/UserApiTest.java - Complete RestAssured example
• ../../../skills-workshop/credit-estimation/CREDIT-ESTIMATION-GUIDE.md - Credit measurement methodology
• RestAssured Documentation
• Spring MockMvc Guide

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: timwukp
• Source: timwukp/agent-skills-best-practice
• License: MIT

Install and usage instructions live in the source repository linked above.