Flutter: How to test a widgets who contains a StreamBuilder?

Question

I'm new on Flutter and I want to add Widgets tests to my app. But I have some problems and questions about widget tests a little more complex than flutter documentation. Indeed i have a Scaffold widget with this body :

body: StreamBuilder<List<UserData>> (
        stream: DatabaseService().searchUser(searchValue),
        builder: (context, snapshot) {
          if (snapshot.hasData && searchValue.length >= 3){
            return ListView.builder(
              itemCount: snapshot.data.length,
              itemBuilder: (context, index) {
                return ListTile(
                  onTap: () {
                    Navigator.pushReplacementNamed(context, '/friends/search/details', arguments: snapshot.data[index]);
                  },
                  title: Text(snapshot.data[index].name),
                );
              }
            );
          }
          return Center();
        },
      )

The first question is:

Is it necessary to test this StreamBuilder?

And if yes: How can I mock the stream and test these widgets ?

Solution

Is it necessary to test this StreamBuilder?

This is subjective. Generally if there is anything that you feel is critical to the functionality of your app, then its better to write a test for it to ensure it works/behaves as expected always.

How can I mock the stream and test these widgets ?

There are tons of resources online to achieve this. Maybe have a look at this?

Comments

[Admin]

Thanks, I looked at this example, but the builder is defined in test, how can I get the builder of my Scaffold widget ?

[Joy Terence]

You could mimic the similar code and then with expect verify the widgets.