APEX REST Service

AnimalLocator.apxc

public class AnimalLocator {
      
    public static String getAnimalNameById(Integer i){
         
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals/' + i);
        request.setMethod('GET');
        HttpResponse response = http.send(request);
        
        
        // If the request is successful, parse the JSON response.
        if(response.getStatusCode() == 200) {
            // Deserializes the JSON string into collections of primitive data types.
            Map<String, Object> result = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            Map<String, Object> animal = (Map<String, Object>) result.get('animal');
            
            
            System.debug('Received the following animal name:');
            System.debug(string.valueOf(animal.get('name')));
            return string.valueOf(animal.get('name'));
            
        } 
        
        return null;    
        
        
        
    }

}

AnimalLocatorMock.apxc

@isTest
global class AnimalLocatorMock implements HttpCalloutMock {
	// Implement this interface method
    global HTTPResponse respond(HTTPRequest request) {
        // Create a fake response
        HttpResponse response = new HttpResponse();
        response.setHeader('Content-Type', 'application/json');
        response.setBody('{"animal": {"id":1,"name": "moose", "eats":"plants","says":"bellows"}}');
        response.setStatusCode(200);
        return response; 
	}
}

AnimalLocatorTest.apxc

@isTest
public class AnimalLocatorTest {
    
    @isTest static void testGetAnimalNameById() {
            Test.setMock(HttpCalloutMock.class, new AnimalLocatorMock());
        	String result = AnimalLocator.getAnimalNameById(1);
        	System.assertEquals('moose', result);
    }
    
    @isTest static void testGetAnimalNameById500() {
        	StaticResourceCalloutMock mock = new StaticResourceCalloutMock();
			mock.setStaticResource('GetAnimalResource');
        	// Set a failed request code - content can be ignored
        	mock.setStatusCode(500);
        	// Associate the callout with a mock response
        	Test.setMock(HttpCalloutMock.class, mock);
        
        	String result = AnimalLocator.getAnimalNameById(1);
        	System.assertEquals(null, result);
    }
    
    
}

AnimalsCallouts.aspx

public class AnimalsCallouts {
    public static HttpResponse makeGetCallout() {
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals');
        request.setMethod('GET');
        HttpResponse response = http.send(request);
        // If the request is successful, parse the JSON response.
        if(response.getStatusCode() == 200) {
            // Deserializes the JSON string into collections of primitive data types.
            Map<String, Object> results = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            // Cast the values in the 'animals' key as a list
            List<Object> animals = (List<Object>) results.get('animals');
            System.debug('Received the following animals:');
            for(Object animal: animals) {
                System.debug(animal);
            }
        }
        return response;
    }
    public static HttpResponse makePostCallout() {
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals');
        request.setMethod('POST');
        request.setHeader('Content-Type', 'application/json;charset=UTF-8');
        request.setBody('{"name":"mighty moose"}');
        HttpResponse response = http.send(request);
        // Parse the JSON response
        if(response.getStatusCode() != 201) {
            System.debug('The status code returned was not expected: ' +
                response.getStatusCode() + ' ' + response.getStatus());
        } else {
            System.debug(response.getBody());
        }
        return response;
    }        
}

AnimalsCalloutsTest.aspx

@isTest
private class AnimalsCalloutsTest {
    @isTest static  void testGetCallout() {
        // Create the mock response based on a static resource
        StaticResourceCalloutMock mock = new StaticResourceCalloutMock();
        mock.setStaticResource('GetAnimalResource');
        mock.setStatusCode(200);
        mock.setHeader('Content-Type', 'application/json;charset=UTF-8');
        // Associate the callout with a mock response
        Test.setMock(HttpCalloutMock.class, mock);
        // Call method to test
        HttpResponse result = AnimalsCallouts.makeGetCallout();
        // Verify mock response is not null
        System.assertNotEquals(null,result, 'The callout returned a null response.');
        // Verify status code
        System.assertEquals(200,result.getStatusCode(), 'The status code is not 200.');
        // Verify content type   
        System.assertEquals('application/json;charset=UTF-8',
          result.getHeader('Content-Type'),
          'The content type value is not expected.');  
        // Verify the array contains 3 items     
        Map<String, Object> results = (Map<String, Object>) 
            JSON.deserializeUntyped(result.getBody());
        List<Object> animals = (List<Object>) results.get('animals');
        System.assertEquals(3, animals.size(), 'The array should only contain 3 items.');          
    }
    
    @isTest 
	static void testPostCallout() {
        // Set mock callout class 
        Test.setMock(HttpCalloutMock.class, new AnimalsHttpCalloutMock()); 
        // This causes a fake response to be sent
        // from the class that implements HttpCalloutMock. 
        HttpResponse response = AnimalsCallouts.makePostCallout();
        // Verify that the response received contains fake values
        String contentType = response.getHeader('Content-Type');
        System.assert(contentType == 'application/json');
        String actualValue = response.getBody();
        System.debug(response.getBody());
        String expectedValue = '{"animals": ["majestic badger", "fluffy bunny", "scary bear", "chicken", "mighty moose"]}';
        System.assertEquals(expectedValue, actualValue);
        System.assertEquals(200, response.getStatusCode());
    }
}

AnimalsHttpCalloutMock.apxc

@isTest
global class AnimalsHttpCalloutMock implements HttpCalloutMock {
    // Implement this interface method
    global HTTPResponse respond(HTTPRequest request) {
        // Create a fake response
        HttpResponse response = new HttpResponse();
        response.setHeader('Content-Type', 'application/json');
        response.setBody('{"animals": ["majestic badger", "fluffy bunny", "scary bear", "chicken", "mighty moose"]}');
        response.setStatusCode(200);
        return response; 
    }
}