flutter_driver's finders should have the equivalent of flutter_test's Finder.evaluate()

[deonchimple]

Steps to Reproduce

Using flutter_driver in the QA environment. Options feels quite limited currently. I am trying to check if an element exists or not, perhaps a function on the like of finder.IsEmpty or something like IfExists in Appium which the skips the element if it doesn't exist and doesn't necessarily throw an exception.

Logs

Application runs fine. Just looking for more functionalities of flutter driver.

Flutter Doctor

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel beta, v0.1.5, on Microsoft Windows [Version 6.1.7601], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK 27.0.3)
[!] Android Studio (version 2.3)
    X Unable to find bundled Java version.
[√] Android Studio (version 3.0)
[√] VS Code (version 1.21.1)
[√] Connected devices (1 available)

! Doctor found issues in 1 category.

[zoechi]

What about
https://docs.flutter.io/flutter/flutter_driver/FlutterDriver/waitFor.html

See also

flutter/packages/flutter_driver/lib/src/driver/driver.dart

Line 748 in 466d154

class CommonFinders {

• flutter/dev/integration_tests/ui/test_driver/driver_test.dart

  Line 24 in e27bcd0

  await driver.waitFor(presentText);

[deonchimple]

@zoechi Unfortunately all this does is wait for the element but doesn't necessarily check if the element is visible/ present (Ideally returning a boolean value).

For instance when I am searching for an element, I would like to give a condition which would go to the next element if the current element isn't found. This requires a boolean function like Ispresent, IsEmpty, isVisible available in Appium and selenium.

[jonsamwell]

@deonchimple can you not assume that if the wait times out that the element is not in the widget tree? If so you could do something like this.

  Future<void> testStep() async {
    final isOpen = await isPresent(find.byType("Drawer"), driver);
    if (isOpen) {
      ...
    }
  }

  Future<bool> isPresent(SerializableFinder finder, FlutterDriver driver, {Duration timeout = const Duration(seconds: 1)}) async {
    try {
      await driver.waitFor(finder, timeout: timeout);
      return true;
    } catch (e) {
      return false;
    }
  }

[brianegan]

@jonsamwell Yep! I've been doing something almost exactly like that and it generally works, but I agree
with the original author that it would be great if that was a method that already existed, since i can imagine a lot of us have that same code in our code bases :)

[akaGelo]

flutter/packages/flutter_driver/lib/src/driver/driver.dart

Line 491 in a817b4e

Future<void> waitForAbsent(SerializableFinder finder, { Duration timeout }) async {

      await driver.waitForAbsent(loginButton);

[Hixie]

Being able to do the equivalent of "Finder.evaluate()" in a driver test would make sense.

[kutlaykural]

But using that function;

Future<bool> isPresent(SerializableFinder finder, FlutterDriver driver, {Duration timeout = const Duration(seconds: 1)}) async {
    try {
      await driver.waitFor(finder, timeout: timeout);
      return true;
    } catch (e) {
      return false;
    }
  }

causes an error log like that
VMServiceFlutterDriver: waitFor message is taking a long time to complete...
is there a way to get rid of that error message?

[Akkasim46]

FlutterDriver does not exist in Flutter 2.5....
So we can use the above method.
any substitute for that method with WidgetTester?