Flutter: how to load file for testing

Just had a go at this and it's easier than you might expect.

First, create a folder that lives in the same directory than your tests are. For example, I created a folder called test_resources.

Then, let's say we have the following JSON file for testing purposes.

test_resources/contacts.json

{  "contacts": [    {      "id": 1,      "name": "Seth Ladd"    },    {      "id": 2,      "name": "Eric Seidel"    }  ]}

test/load_file_test.dart

We could use it for our test like so:

import 'dart:convert';import 'dart:io';import 'package:flutter_test/flutter_test.dart';void main() {  test('Load a file', () async {    final file = new File('test_resources/contacts.json');    final json = jsonDecode(await file.readAsString());    final contacts = json['contacts'];    final seth = contacts.first;    expect(seth['id'], 1);    expect(seth['name'], 'Seth Ladd');    final eric = contacts.last;    expect(eric['id'], 2);    expect(eric['name'], 'Eric Seidel');  });}

I encountered this same issue today. My tests passed in my IDE (Android Studio) but failed on CI. I found that the IDE wanted a non-relative path but flutter test wants a relative path. I think this is a bug and I'll be looking for the right place to report it. However, I found a crude work around for the meantime. Basically, I have a function which tries both ways to specify the file path..

import 'dart:convert';import 'dart:io';Future<Map<String, dynamic>> parseRawSample(String filePath,    [bool relative = true]) async {  filePath = relative ? "test_data/src/samples/raw/$filePath" : filePath;  String jsonString;  try {    jsonString = await File(filePath).readAsString();  } catch (e) {    jsonString = await File("../" + filePath).readAsString();  }  return json.decode(jsonString);}

much of that code is specific to my situation, but I think others could probably adapt this work around for their purposes.

i created an util because vscode and command line test base path is different

https://github.com/terryx/flutter-muscle/blob/master/github_provider/test/utils/test_path.dart

this is how i use it

https://github.com/terryx/flutter-muscle/blob/master/github_provider/test/services/github_test.dart#L13

Another way is to specify exact test path in command line

$ flutter test test