1.3Writing Test Scripts

Postman's test scripts run after each request, validating responses inline.

Basic Assertions

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

// Response has expected fields
pm.test("Response has user ID", () => {
    const data = pm.response.json();
    pm.expect(data.id).to.be.a("number");
    pm.expect(data.email).to.be.a("string");
    pm.expect(data).to.not.have.property("password");
});

// Response time
pm.test("Response time < 500ms", () => {
    pm.expect(pm.response.responseTime).to.be.below(500);
});

// Headers
pm.test("Content-Type is JSON", () => {
    pm.response.to.have.header("Content-Type", "application/json; charset=utf-8");
});

Chaining Requests

Extract data from one request and use it in the next:

// In POST /auth/login Tests tab:
pm.test("Save auth token", () => {
    const token = pm.response.json().access_token;
    pm.environment.set("auth_token", token);
});

// In subsequent requests, use {{auth_token}} in the Authorization header:
// Bearer {{auth_token}}

Dynamic Variables

Postman provides built-in dynamic variables:

{{$randomEmail}}      -> random email address
{{$randomFullName}}   -> random name
{{$randomUUID}}       -> UUID v4
{{$timestamp}}        -> current Unix timestamp
{{$randomInt}}        -> random integer