How to validate Response by Matchers API in Rest Assured

  

How to Use Hamcrest Matchers in GET API via Rest Assured

Hamcrest is a framework for writing matcher objects, which allow 'match' rules to be defined declaratively. In Rest Assured, we use Hamcrest matchers to write expressive assertions for validating the API response.

Maven Dependencies:

<dependencies>
    <!-- Rest Assured -->
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>rest-assured</artifactId>
        <version>5.3.0</version>
        <scope>test</scope>
    </dependency>

    <!-- Hamcrest -->
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest</artifactId>
        <version>2.2</version>
        <scope>test</scope>
    </dependency>
</dependencies>

Commonly Used Hamcrest Matchers

Matcher	Description
equalTo(value)	Check equality
hasItem(value)	Check if a list contains item
hasItems(val1, val2)	Check if list contains multiple items
not(value)	Asserts the opposite
containsString(str)	Check substring match
startsWith(str)	Check if string starts with

API to be tested:

https://reqres.in/api/users?page=2

Java Code:

import io.restassured.RestAssured;
import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;

public class GetApiHamcrestExample {
    public static void main(String[] args) {

        // Set base URI
        RestAssured.baseURI = "https://reqres.in";

        // GET Request with Hamcrest matchers for assertions
        given()
            .log().all()
        .when()
            .get("/api/users?page=2")
        .then()
            .log().all()
            .statusCode(200)
            .body("page", equalTo(2))  // validate page number
            .body("data.id", hasItems(7, 8, 9))  // check if certain user IDs are present
            .body("data.first_name", hasItem("Michael"))  // check first_name list contains value
            .body("support.url", containsString("reqres.in"))  // substring match
            .body("data.email[0]", startsWith("michael"));  // starts with
    }
}

Output:

Request:
GET https://reqres.in/api/users?page=2

Response:
200 OK
...
Assertions:
page == 2
data.id contains 7, 8, 9
data.first_name contains "Michael"
support.url contains "reqres.in"
data.email[0] startsWith "michael"