Partial Update with PATCH

How it works

PATCH sends a set of changes instead of a full replacement. You name only the fields you want different, and the server merges them into the stored record. That makes it lighter than PUT and safer when several clients edit different fields of the same resource.

On testkru, PATCH /users/1 takes whatever JSON object you send and merges it over user 1, then returns the whole merged record with all five fields. Send only a new city and the response still carries John Doe, his email and age 30, with the city swapped. An empty object {} counts as no body at all and is refused with 400, as is a request with no JSON content type.

REST Assured has a patch() method next to get(), post() and put(), and the rest of the chain is identical: content type, body, path. Because the reply is the full record, one response lets you check both halves of the contract, the field you changed and the fields you did not touch.

About the assignment

Move user 1 to a new city with a one-field PATCH and prove from the response that the name survived the update unchanged.

What you will do

1. 1Prepare the request with given(), the JSON content type and a body holding just the new city from the starter.
2. 2Send it with patch() to /users/1.
3. 3Print the status code after Status:.
4. 4Print the name field after Name: and the city field after City:, both read from the same response.

Common mistakes

• Using put() by habit

  The same one-field body sent with put() is rejected with 400 because PUT requires name and email. The verb is the whole point of this lesson.

• Patching with an empty object

  Sending {} to see what happens returns 400 with a message asking for fields to update. A PATCH needs at least one field.

• Only checking the changed field

  Asserting that city changed proves half the behaviour. The bug PATCH tests exist to catch is a server that wipes the other fields, so assert on an untouched one such as name too.

In a real test suite

Related lessons

• Full Update with PUTThe full-replacement PUT on the same user, for direct comparison.
• Validate Multiple FieldsChains several body() matchers in one then(), the pattern a PATCH check needs.
• Handle PUT Validation ErrorShows what PUT does when a required field is missing.

To try one of these calls on any API endpoint without a task, open the Online Selenium Java Compiler (REST Assured is included).

Starter code

The editor above opens with this code. Fill in the TODO lines, then run and submit it.

import io.restassured.RestAssured;
import io.restassured.response.Response;
import io.restassured.specification.RequestSpecification;
import io.restassured.http.ContentType;
import static io.restassured.RestAssured.*;

public class Main {
    public static void main(String[] args) {
        RestAssured.baseURI = "https://testkru.com/api";

        // TODO: PATCH /users/1 with body: {"city": "San Francisco"}
        // TODO: Print status, name (should still be "John Doe"), and city (should be updated)
    }
}