What's the best way to generate a fake response to write unit tests?

[GP4cK]

Often, in my code, I have something like this:

Query(
  options: QueryOptions(
    document: ItemsQuery().document
    variables: ItemsArguments(...),
  ),
  builder: (result, { refetch, fetchMore }) {
    // skipping error handling etc.
    final data = ItemsQuery().parse(result.data);
    return MyWidget(data);
  },
);

When I want to write a test for MyWidget, I need to generate data to pass as an input. I can think of several solutions:

The first one is to manually create a json and do something like:

final json = [{
  'id': 'id0',
  'title': 'Title 0',
  'description': 'Description 0',
}, {
  'id': 'id1',
  // ...
}];
final data = ItemsQuery().parse(json);
await WidgetTestHelper.generateApp(tester, MyWidget(data));
expect(...);

This works ok but people may make mistakes when writing the JSON. I've already seen this happening in my team.

The other solution is to do something like:

final json = [
  (Items$Query$Item()
    ..id = 'id0'
    ..title = 'Title 0'
    ..description = 'Description 0').toJson()
];
final data = ItemsQuery().parse(json);
//...

This is slightly better because the editor will catch typos or attributes that do no exist.
But it gets really tedious when there are nested object in the response. Ex:

Items$Query$Item()
  ..id = 'id0'
  ..title = 'Title 0'
  ..description = 'Description 0
  ..createdBy = (Items$Query$Item$CreatedBy()
    ..username = 'Alice'
    ..address = (Items$Query$Item$CreatedBy$Address() // <- this is very long
      // ...

Do you guys have a better way of doing this?

[comigor]

Hi @GP4cK!

In my work, for unit tests, we're doing your second example. Although kinda boring to write, it is surely safer than the first option. One of the teams is working on a code generator solution to mock those classes generated by Artemis, though. I'll reach them to see if they plan to ship it as opensource.

[GP4cK]

Thanks a lot @comigor. Shall we close this now or we wait for the team's answer?

[comigor]

I've send this link to them asking if they have any plans. Let's keep this open and I'll remember to update!