feat(utils): added waitUntil util and updated docs

CHANGELOG.md

@@ -1,6 +1,8 @@
-## [1.1.4] - 26/09/2019
-* Added configuration parameter `flutterBuildTimeout` to allow setting the app build wait timeout.  Slower machine may need longer to build and start a Flutter app under test.
+## [1.1.4] - 27/09/2019
+* Added configuration parameter `flutterBuildTimeout` to allow setting the app build wait timeout.  Slower machines may need longer to build and start the Flutter app under test.
 * Now logging the flutter driver command used when the configuration setting `logFlutterProcessOutput` is true
+* Verbose logging for the underlying Flutter process can be enabled via the configuration setting `verboseFlutterProcessLogs`
+* Added `waitUntil` helper method to the `FlutterDriverUtils` class that waits until a certain provided condition is true
 
 ## [1.1.3] - 25/09/2019
 * Added Flutter driver reporter - the Flutter Driver logs all messages (even non-error ones) to stderr and will cause the process to be marked as failed by a CI server becuase of this.  So this reporter redirects the messages to the appropiate output stream (stdout / stderr).

README.md

@@ -927,7 +927,7 @@ For convenience the library defines a number of pre-defined steps so you can get
 
 #### Flutter Driver Utilities
 
-For convenience the library provides a static `FlutterDriverUtils` class that abstracts away some common Flutter driver functionality like tapping a button, getting and entering text, checking if an element is present or absent.  See [lib/src/flutter/utils/driver_utils.dart](lib/src/flutter/utils/driver_utils.dart).
+For convenience the library provides a static `FlutterDriverUtils` class that abstracts away some common Flutter driver functionality like tapping a button, getting and entering text, checking if an element is present or absent, waiting for a condition to become true.  See [lib/src/flutter/utils/driver_utils.dart](lib/src/flutter/utils/driver_utils.dart).
 
 ### Debugging
 

lib/src/flutter/utils/driver_utils.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter_driver/flutter_driver.dart';
 
 class FlutterDriverUtils {
@@ -50,4 +52,31 @@ class FlutterDriverUtils {
     await driver.tap(finder, timeout: timeout);
     await FlutterDriverUtils.waitForFlutter(driver, timeout: timeout);
   }
+
+  /// Waits until the [condition] returns true
+  /// Will raise a complete with a [TimeoutException] if the
+  /// condition does not return true with the timeout period.
+  static Future<void> waitUntil(
+    FlutterDriver driver,
+    Future<bool> condition(), {
+    Duration timeout = const Duration(seconds: 10),
+    Duration pollInterval = const Duration(milliseconds: 500),
+  }) async {
+    return Future.microtask(() async {
+      final completer = Completer<void>();
+      int maxAttempts =
+          (timeout.inMilliseconds / pollInterval.inMilliseconds).round();
+      int attempts = 0;
+
+      while (attempts < maxAttempts) {
+        final result = await condition();
+        if (result) {
+          completer.complete();
+          break;
+        } else {
+          await Future.delayed(pollInterval);
+        }
+      }
+    }).timeout(timeout);
+  }
 }

pubspec.lock

@@ -104,7 +104,7 @@ packages:
       name: gherkin
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.1.3"
   glob:
     dependency: "direct main"
     description:

pubspec.yaml

@@ -16,7 +16,7 @@ dependencies:
     sdk: flutter
   glob: ^1.1.7
   meta: ">=1.1.6 <2.0.0"
-  gherkin: ^1.1.2
+  gherkin: ^1.1.3
 
 dev_dependencies:
   test: ">=1.6.1 <1.7.0"