Rest API possible test cases [closed]

Question

I'm working in rest api testing. Currently I test when request send and json response generate or not. I'm test with positive and negative values to put in parameters in the url. Now I need to test so many case like...

Other possible test cases:

• What happens if you send malformed requests to the API?

  • Does your API have state? I.e., are there any logical sequences of API calls (e.g., login, search item, place item in cart, checkout) that influence API behavior?
• What's the API performance?
• Is the API secured? If so, can you break the security?

How to perform these possible cases ? or Is there any extra possible test case are there ? please tell anybody..

Here is my code what should I need to test ? What are the possiblities that I need to test in rest api ? Or anything else needed in rest api testing?

package com.qber.test;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

import static com.jayway.restassured.RestAssured.given;
import static org.hamcrest.CoreMatchers.equalTo;

/**
 * Created by naveen on 15/12/16.
 */
public class registerCounter {
    @Test(dataProvider = "register")
    public void md5JsonTest(String secret,String mac,String id, String md5Hash) {

        given().
                parameters("s", secret).parameters("m",mac).parameters("d",id).
                when().
                get("http://baseUrl/register/device").
                then().
                assertThat().
                body("md5", equalTo(md5Hash));
    }

    @DataProvider(name = "register")
    public Object[][] createMD5TestData() {

        return new String[][] {
                {"1c40f4","063f98d2621038a7af64ba893f2540e0","10","REG_DEV_01"}
        };
    }

}

In my project there were 25 api are there I just made 25 separate class files for api's and test with same code. is it correct or not ? What should I need to do ? Anybody please help me to give a valuable answer