REST API Testing: The Complete Engineering Guide

// 1. Assert HTTP Status Code
pm.test("Status code is 201 Created", function () {
    pm.response.to.have.status(201);
});

// 2. Assert Response Time SLA (< 400ms)
pm.test("Response time is under 400ms", function () {
    pm.expect(pm.response.responseTime).to.be.below(400);
});

// 3. Extract and assert JSON body fields
const response = pm.response.json();

pm.test("Account created with correct initial balance", function () {
    pm.expect(response).to.have.property("accountId");
    pm.expect(response.status).to.eql("ACTIVE");
    pm.expect(response.balance).to.be.at.least(0);
});

// 4. Save extracted ID into Environment Variable for downstream calls
pm.environment.set("currentAccountId", response.accountId);

package com.testerrank.api.tests;

import io.restassured.RestAssured;
import io.restassured.builder.RequestSpecBuilder;
import io.restassured.http.ContentType;
import io.restassured.specification.RequestSpecification;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

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

public class BankingApiTest {

    private RequestSpecification requestSpec;

    @BeforeClass
    public void setupSpecification() {
        requestSpec = new RequestSpecBuilder()
            .setBaseUri("https://www.testerrank.com")
            .setBasePath("/api")
            .setContentType(ContentType.JSON)
            .addHeader("Accept", "application/json")
            .build();
    }

    @Test(description = "Verify fund transfer API validates account balances")
    public void testFundTransferValidation() {
        String transferPayload = """
        {
            "fromAccount": "ACC-10029",
            "toAccount": "ACC-99482",
            "amount": 250.00,
            "currency": "USD"
        }
        """;

        given()
            .spec(requestSpec)
            .header("Authorization", "Bearer mock_jwt_token_sample_2026")
            .body(transferPayload)
        .when()
            .post("/practice/banking/transfers")
        .then()
            .statusCode(200)
            .body("status", equalTo("COMPLETED"))
            .body("referenceNumber", notNullValue())
            .body("remainingBalance", greaterThanOrEqualTo(0.0f))
            .time(lessThan(1000L)); // Assert response latency within 1000ms
    }
}

import static io.restassured.module.jsv.JsonSchemaValidator.matchesJsonSchemaInClasspath;

@Test(description = "Verify customer account payload adheres to JSON Schema Draft-07")
public void verifyAccountContractSchema() {
    given()
        .spec(requestSpec)
    .when()
        .get("/practice/banking/accounts/ACC-10029")
    .then()
        .statusCode(200)
        // Validates entire response payload matches src/test/resources/schemas/account-schema.json
        .body(matchesJsonSchemaInClasspath("schemas/account-schema.json"));
}

# Install Newman globally via npm
npm install -g newman newman-reporter-htmlextra

# Execute Postman collection with environment variables and generate HTML report
newman run tests/postman_collection.json \
  --environment env/staging.json \
  --reporters cli,htmlextra \
  --reporter-htmlextra-export reports/api-report.html \
  --bail # Exit immediately with non-zero code if critical smoke tests fail