api-to-testcase-generator

Files (3)

• SKILL.md
• framework-templates.md · reference/
• openapi-parsing-guide.md · reference/

SKILL.md (first lines)

# API-to-Test Case Generator

Converts API definitions into production-ready test suites covering happy paths, edge cases,
error handling, and boundary conditions.

---

## Supported Input Formats

| Format | Example |
|---|---|
| OpenAPI 3.x YAML/JSON | `openapi: 3.0.0` |
| Swagger 2.0 | `swagger: "2.0"` |
| Postman Collection v2.x | JSON export from Postman |
| Raw curl commands | `curl -X POST https://...` |
| Plain English description | "POST /users creates a user with name and email" |
| HTTP request/response examples | Paste raw request + response |
| Code (route handlers / controllers) | Express.js, FastAPI, Spring, etc. |

---

## Supported Test Frameworks

| Language | Frameworks |
|---|---|
| Python | `pytest` + `requests` or `httpx` |
| JavaScript/TypeScript | `Jest`, `Mocha`/`Chai`, `Supertest` |
| Java | `JUnit 5` + `RestAssured` |
| Go | `testing` + `net/http/httptest` |
| API-level (language-agnostic) | `Newman` (Postman), `k6` (load), plain `.http` files |

If the user doesn't specify a framework, **ask** — or default to `pytest` for Python APIs, `Jest` for JS/TS APIs.

---

## Workflow

### Step 1 — Parse the API Definition

Extract from the input:
- **Endpoints**: method + path (e.g., `POST /api/v1/users`)
- **Request**: headers, query params, path params, body schema (required vs optional fields, types)
- **Response**: status codes, response body schema, headers
- **Auth**: Bearer token, API key, Basic auth, OAuth2
- **Constraints**: min/max, enum values, format (email, uuid, date-time), nullable

If input is ambiguous or incomplete, ask the user to clarify before generating.

### Step 2 — Determine Test Strategy

For each endpoint, generate tests across these categories:

#### ✅ Happy Path Tests
- Valid request with all required fields → expect `2xx`
- Valid request with all optional fields included
- Minimal valid request (required fields only)

#### ❌ Validation / Error Tests
- Missing required fields → expect `400`/`422`
- Invalid field types (string where int expected, etc.)
- Out-of-range values (below min, above max)
- Invalid enum values
- Malformed request body (invalid JSON)
- Extra/unknown fields (if strict validation expected)

#### 🔒 Auth / Authorization Tests
- No auth token → expect `401`
- Invalid/expired token → expect `401`
- Insufficient permissions → expect `403`
- Valid token → expect success

#### 🔍 Edge Cases
- Empty string / null for optional fields
- Maximum-length strings
- Boundary values (min, max, min-1, max+1)
- Special characters in string fields
- Idempotency (repeat same request — does it behave correctly?)

#### 🌐 Integration / Flow Tests (when multiple endpoints provided)
- Create → Read → Update → Delete flows
- Pagination (first page, last page, page out of range)
- Filtering and sorting combinations

### Step 3 — Generate Test Code

Follow the structure below per framework. See `reference/framework-templates.md` for detailed templates.

**General principles:**
- Each test should be atomic and independent (no shared mutable state)
- Use descriptive test names: `test_create_user_returns_201_with_valid_payload`
- Parameterize similar tests where appropriate (pytest `@pytest.mark.parametrize`, Jest `test.each`)
- Group tests by endpoint in a class or describe block
- Extract base URL, auth tokens, and reusable fixtures into a shared setup section
- Assert on: status code, response body fields, response headers (content-type), response time if relevant

### Step 4 — Output Structure

Present output as:
1. **Summary table** — endpoints covered, test count per category
2. **Test file(s)** — complete, runnable code
3. **Setup instructions** — how to install deps and run the suite
4. **Coverage gaps** — any untestable scenarios due to missing spec info

---

## Output Examples by Framework

### pytest (Python)

```python
import pytest
import requests

BASE_URL = "https://api.example.com"
HEADERS = {"Authorization": "Bearer YOUR_TOKEN", "Content-Type": "application/json"}

class TestCreateUser:
    def test_valid_payload_returns_201(self):
        payload = {"name": "Alice", "email": "alice@example.com"}

From LambdaTest/agent-skills, MIT.

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