Postman Generator

Postman Generator

Create Postman collections (v2.1.0 format) and environments from API specs, Swagger/OpenAPI yaml/json, route handlers, or API description files. Generate JavaScript test scripts validating RESTful compliance, security headers, schema accuracy, and execute them using Newman.

Quick Start

/postman-generator create new collections and env from <context>
/postman-generator validate --collection <collection_path> [--env <environment_path>]
/postman-generator run --collection <collection_path> --env <environment_path>
/postman-generator install-newman

Commands Details

• Create: /postman-generator create new collections and env from <context> Parses the context and automatically outputs configured Postman Collections, Environments, and JavaScript RESTful tests.
• Validate: /postman-generator validate --collection <collection_path> [--env <environment_path>] Runs the Postman collection via Newman, executes all embedded JavaScript assertions, checks status codes, and outputs a validation summary highlighting errors.
• Run: /postman-generator run --collection <collection_path> --env <environment_path> Launches the Newman runner to execute the specified test collection under the given environment scope.
• Install Newman: /postman-generator install-newman Ensures the Newman execution package is properly installed on the host workspace.

Supported Inputs

• OpenAPI / Swagger Specs: openapi.yaml, openapi.json, swagger.json
• Code Route Files: Express (router.get), Fastify (app.get), NestJS controllers, Next.js API route handlers, Hono, Django, FastAPI.
• Raw API Documentation: Markdown files, text file lists of endpoints.

🛠️ Step-by-Step Execution Workflow

When running /postman-generator create new collections and env from <context>:

1. Analyze Context & Discover Endpoints

• Discover endpoint paths, request methods (GET, POST, PUT, DELETE, etc.), query parameters, path variables, request bodies (JSON/form-data), and potential response structures.
• Map out authentications (Bearer token, API Keys, Basic Auth).

2. Identify Test Scenarios (RESTful Best Practices)

For each endpoint, design a request item in the collection with corresponding Postman JS test scripts inside event arrays of type test:

• Success Scenarios:
  • GET / PUT / PATCH: Expect 200 OK
  • POST (Creation): Expect 201 Created
  • DELETE: Expect 204 No Content or 200 OK
• Failure/Edge-case Scenarios (if payload/routes details exist):
  • Request with missing required parameters: Expect 400 Bad Request or 422 Unprocessable Entity
  • Request with invalid/missing token: Expect 401 Unauthorized
  • Request with restricted access role: Expect 403 Forbidden
  • Request for non-existent ID: Expect 404 Not Found
  • Request violating uniqueness/constraints: Expect 409 Conflict

3. Generate Postman Collection JSON (v2.1.0)

Structure the collection JSON following the official Schema v2.1.0. Include:

• A descriptive name and info block.
• Folders grouping endpoints logically (e.g. Auth, Users, Products).
• Requests with variables ({{baseUrl}}, {{token}}, path variables as :id).
• Pre-request scripts (if needed for timestamps or signature generation).
• Postman JS Test Scripts embedded in "event" arrays:

  "event": [
    {
      "listen": "test",
      "script": {
        "exec": [
          "pm.test(\"Status code is 200\", function () {",
          "    pm.response.to.have.status(200);",
          "});",
          "pm.test(\"Response time is below 500ms\", function () {",
          "    pm.expect(pm.response.responseTime).to.be.below(500);",
          "});",
          "pm.test(\"Content-Type is application/json\", function () {",
          "    pm.response.to.have.header(\"Content-Type\", /json/);",
          "});"
        ],
        "type": "text/javascript"
      }
    }
  ]
  

4. Create Postman Environment JSON

Write a corresponding environment config file with placeholders:

• baseUrl: Base URL of the API.
• token or authentication variables.
• Dynamic ID placeholders populated from previous test scripts.

5. Install & Run Newman

• Install newman CLI for the user if it's not present:
  • Try using plugins/postman-generator/scripts/newman-runner.sh install
• Run the collections:
  • Run plugins/postman-generator/scripts/newman-runner.sh run <collection_path> [environment_path]
  • Output execution summaries to the terminal.

📄 Postman Collection Format Reference (v2.1.0)

Your generated collection MUST be valid JSON. Keep this structural boilerplate in mind:

{
  "info": {
    "_postman_id": "unique-uuid",
    "name": "My API Collection",
    "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
  },
  "item": [
    {
      "name": "Authentication",
      "item": [
        {
          "name": "Login User",
          "event": [
            {
              "listen": "test",
              "script": {
                "exec": [
                  "pm.test(\"Status code is 200\", function () {",
                  "    pm.response.to.have.status(200);",
                  "});",
                  "pm.test(\"Login successful - token received\", function () {",
                  "    var jsonData = pm.response.json();",
                  "    pm.expect(jsonData).to.have.property(\"token\");",
                  "    pm.environment.set(\"token\", jsonData.token);",
                  "});"
                ],
                "type": "text/javascript"
              }
            }
          ],
          "request": {
            "method": "POST",
            "header": [
              {
                "key": "Content-Type",
                "value": "application/json"
              }
            ],
            "body": {
              "mode": "raw",
              "raw": "{\n  \"email\": \"user@example.com\",\n  \"password\": \"password123\"\n}"
            },
            "url": {
              "raw": "{{baseUrl}}/auth/login",
              "host": [
                "{{baseUrl}}"
              ],
              "path": [
                "auth",
                "login"
              ]
            }
          }
        }
      ]
    }
  ]
}

📄 Postman Environment Format Reference

The generated environment file should follow this structure:

{
  "name": "API Testing Environment",
  "values": [
    {
      "key": "baseUrl",
      "value": "http://localhost:3000",
      "type": "text",
      "enabled": true
    },
    {
      "key": "token",
      "value": "",
      "type": "text",
      "enabled": true
    }
  ],
  "_postman_variable_scope": "environment"
}

🛡️ Best Practice Test Assertions to Include

1. Schema Validation via Ajv (Standard in Postman):

   const schema = {
       "type": "object",
       "required": ["id", "name"],
       "properties": {
           "id": { "type": "string" },
           "name": { "type": "string" }
       }
   };
   pm.test("Schema matches contract", function () {
       pm.response.to.have.jsonSchema(schema);
   });
   

2. Security Headers:

   pm.test("Strict-Transport-Security header is present", function () {
       pm.response.to.have.header("Strict-Transport-Security");
   });
   

3. Array Type Checks:

   pm.test("Response is an array with items", function () {
       var jsonData = pm.response.json();
       pm.expect(jsonData).to.be.an("array");
       if (jsonData.length > 0) {
           pm.expect(jsonData[0]).to.have.property("id");
       }
   });
   

📥 Newman CLI Installation instructions

If Newman is not installed, inform the user they can run the installer script: bash plugins/postman-generator/scripts/install.sh Or use the runner tool plugins/postman-generator/scripts/newman-runner.sh install which handles dependencies natively or via npx.