It is very common to use API in our Flutter projects. Testing makes the Flutter project very easy to maintain, in this way you will save a lot of debugging time. Also when you have testing in place you can always check whether API working as expected. 

Let’s create a simple API endpoint in PHP in our local server. If you don’t anything about PHP web development, It’s quite fun to work in PHP. This PHP file just responds with a JSON which has a list of Books, nothing complex right? 



$b1 = ['title' => 'Beginning App Development with Flutter', 'author' => 'Rap Payne'];
$b2 = ['title' => 'Beginning Flutter: A Hands On Guide to App Development', 'author' => 'Marco L. Napoli'];
$b2 = ['title' => 'Flutter Apprentice', 'author' => 'Vincenzo Guzzi, Kevin D Moore, Vincent Ngo and Michael Katz'];

$books = [$b1, $b2];

header("content-type: application/json; charset=UTF-8");
echo json_encode($books, JSON_PRETTY_PRINT);

        "title": "Beginning App Development with Flutter",
        "author": "Rap Payne"
        "title": "Flutter Apprentice",
        "author": "Vincenzo Guzzi, Kevin D Moore, Vincent Ngo and Michael Katz"


Let’s first create a flutter project called “api_test”, we will use VSCode for the rest of the project.

flutter create api_test

Let’s add http package by this command, run on your terminal.

flutter pub add http

Go to your lib folder and create two files model.dart and service.dart.


On the model.dart creates a book class.

class Book {
  final String title;
  final String author;

  Book({required this.title, required});


In the service, class create an abstract class like this 

abstract class BookApi {
import 'package:api_test/model.dart';
import 'package:http/http.dart' as http;
import 'dart:convert' as convert;

abstract class BookApi {
  Future<List<Book>> books();

class BookService implements BookApi {
  Future<List<Book>> books() async {
    var url = Uri.parse('http://localhost/flutter/book.php');
    var response = await http.get(url);

    if (response.statusCode == 200) {
      final listResponse = convert.jsonDecode(response.body) as List;
      List<Book> books = listResponse
            (e) => Book(
              title: e['title'],
              author: e['author'],
      return books;
    } else {
      print('Request failed with status: ${response.statusCode}.');
      return [];

create another class in the same file for the above BookApi method implementation


Create a test file called book_service_test.dart in test folder

import 'package:api_test/model.dart';
import 'package:api_test/service.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  var book_service = BookService();

  test('book api', () async {
    final result = await book_service.books();
    print(" test $result");

    expect(result.isNotEmpty, true);
    expect(result, isA<List<Book>>());

Our tests are passed when the list is not empty and list has a book type.

Download the full source code

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