network_image_mock

Package Overview

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A utility package for mocking Image.network responses in Flutter widget tests. It allows developers to simulate network image loading without making actual HTTP requests, ensuring consistent and reliable test results. Ideal for testing UI components that display images from remote sources, it provides a simple way to return placeholder images or predefined assets during testing. The package is lightweight and integrates seamlessly with Flutter's testing framework.

Use cases

Testing widgets that display remote images
Simulating image loading states
Avoiding network calls in unit tests
Validating image placeholders
Ensuring test consistency

Key features

Mock Image.network responses
Supports placeholder images
No external network dependencies
Easy integration with test files
Works across all Flutter platforms

Suitable for

Flutter developers writing widget tests
Teams requiring stable test environments
Projects with frequent UI changes involving images
Test automation engineers
CI/CD pipelines

Considerations

Not intended for production use
Requires manual setup in test files
Limited to image mocking scenarios
Does not handle image caching
Must be removed from production dependencies

Original README

Original README snapshot from the linked source repository. Visit the repository for the latest content.

Network Image Mock

GitHub code size in bytes

A utility for providing mocked response to Image.network in Flutter widget tests.

Introduction

Since you are here you probably already know that calling Image.network results in 400 response in Flutter widget tests. The reason for this is that default HTTP client in tests always return a 400.

So, what can we do about it? Instead of copying the whole code over and over again for mocking the HTTP client, I created this package. It is heavily inspired by roughike/image_test_utils, however that package is not being maintained despite multiple pull requests asking for bumping the mockito version and making the package usable again.

Installing

Null safety

This package should be installed under dev_dependencies with

dev_dependencies:
  network_image_mock: ^2.0.1

Without null safety (deprecated)

If you have legacy unmigrated code that does not use Null safety, install under dev_dependencies with

dev_dependencies:
  network_image_mock: 1.1.0

Example

The package is quite straightforward to use. All you have to do is include it in your test file and wrap widget testing functions that require proper Image.network response in mockNetworkImagesFor() function provided by this package. A full test example could look like this.

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:network_image_mock/network_image_mock.dart';

Widget makeTestableWidget() => MaterialApp(home: Image.network(''));

void main() {
  testWidgets(
    'should properly mock Image.network and not crash',
    (WidgetTester tester) async {
      mockNetworkImagesFor(() => tester.pumpWidget(makeTestableWidget()));
    },
  );
}

This is actually an example taken from tests for this package.

Contributing

There is not much to contribute since the package serves its purpose, however, in chance of needing to bump or adjust some version, or any other suggestion for that matter, please read CONTRIBUTING.