flutter 测试未找到小部件

Question

I have this code that test if the button is on the screen:

void main() {
  testWidgets('Search for button', (WidgetTester tester) async {
    await tester.pumpWidget(MaterialApp(
      home: HomeView(),
    ));
    final button = find.byType(BotaoRedirecionamentoInterno);
    expect(button, findsWidgets);
  });
}

Is working as I expected, but when I try this code that search for another type of button in the same view it doenst work:

void main() {
  testWidgets('Search for button', (WidgetTester tester) async {
    await tester.pumpWidget(MaterialApp(
      home: HomeView(),
    ));
    final button = find.byType(BotaoRedirecionamentoExterno);
    expect(button, findsWidgets);
  });
}

I don't understand why because they are exactly one line below in the HomeView:

      Expanded(
        child: GridView.count(
          childAspectRatio: 6,
          padding: EdgeInsets.only(left: screenWidth * .05, right: screenWidth * .05),
          mainAxisSpacing: screenHeight * 0.02,
          crossAxisCount: 1,
          children: const [
            BotaoRedirecionamentoInterno(texto: "aaa", rota: '/bbbb'),
            BotaoRedirecionamentoExterno(texto: 'aaa', url: "bbb"),
            BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
            BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
            BotaoRedirecionamentoExterno(texto: "aaa", url: 'bbb'),
            BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
          ],
        ),
      )

this is the error message:

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure object was thrown running a test:
  Expected: at least one matching node in the widget tree
  Actual: _WidgetTypeFinder:<zero widgets with type "BotaoRedirecionamentoExterno" (ignoring
offstage widgets)>

I discovered that if I change the position inside the GridView to this:

 Expanded(
            child: GridView.count(
              childAspectRatio: 6,
              padding: EdgeInsets.only(left: screenWidth * .05, right: screenWidth * .05),
              mainAxisSpacing: screenHeight * 0.02,
              crossAxisCount: 1,
              children: const [
                BotaoRedirecionamentoExterno(texto: 'aaa', url: "bbb"),
                BotaoRedirecionamentoInterno(texto: "aaa", rota: '/bbbb'),

                BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
                BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
                BotaoRedirecionamentoExterno(texto: "aaa", url: 'bbb'),
                BotaoRedirecionamentoExterno(texto: "aaa", url: "bbb"),
              ],
            ),
          )

The test finds the BotaoRedirecionamentoInterno but wont find BotaoRedirecionamentoExterno, so my guess is that is only finding the first widget inside the GridView.

Anyone could help me figure out what is happening?

Answer 1

Use dragUntilVisible which scrolls the GridView in right direction, look below one it will scroll till the BotaoRedirecionamentoExterno widget, you can replace it with any Key or Text ..

await tester.dragUntilVisible(
    find.byType(BotaoRedirecionamentoExterno), // what you want to find
    find.byType(GridView), // widget you want to scroll
    const Offset(-250, -0), // delta to move
);

Answer 2

The test may actually work as intended: your second child widget in the Exanded my not be visible on screen, and can therefore not be found. The find methods will only return Widgets that have been created, and the Gridview will not create all widgets if they are not visible. The fact that it does show up if you swap the order suggests that the first Interno widget is large.