postman-test-script-generator

Postman Test Script Writer

Writes and embeds Postman JavaScript test scripts — both prerequest and test scripts — into collection requests. Works from an existing collection JSON or a plain description.

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Postman Scripting Basics

Postman scripts use the pm object and run in a sandboxed JS environment (no Node.js builtins).

Key APIs

// --- Assertions ---
pm.test("description", () => { pm.expect(...).to... });

// --- Response access ---
pm.response.code           // HTTP status code (number)
pm.response.json()         // Parse body as JSON
pm.response.text()         // Body as string
pm.response.headers.get("Content-Type")
pm.response.responseTime   // ms (number)

// --- Variables ---
pm.environment.set("key", value);
pm.environment.get("key");
pm.collectionVariables.set("key", value);
pm.collectionVariables.get("key");
pm.variables.get("key");   // resolves: local > data > env > collection > global

// --- Pre-request ---
pm.request.headers.add({ key: "X-Header", value: "val" });

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Step 1 — Understand What to Test

Identify the user's intent across these categories:

Category	Examples
Status assertion	"should return 200", "expect 201 on create"
Schema/field check	"response must have id and name", "check nested field"
Value assertion	"user.email equals input", "count > 0"
Response time	"must respond under 500ms"
Chaining	"save token from login response for next request"
Dynamic pre-request	"generate timestamp before request", "set random ID"
Error handling	"if 401, log warning", "check error message format"

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Step 2 — Write the Scripts

Status Code

pm.test("Status is 200", () => {
  pm.response.to.have.status(200);
});

JSON Field Existence

pm.test("Response has required fields", () => {
  const body = pm.response.json();
  pm.expect(body).to.have.property("id");
  pm.expect(body).to.have.property("name");
});