Eliminate unused retry.dart from flutter_driver (#13161)

packages/flutter_driver/lib/src/retry.dart

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:async';
-
-/// Performs an action and returns either the result of the action or a [Future]
-/// that evaluates to the result.
-typedef dynamic Action();
-
-/// Determines if [value] is acceptable. For good style an implementation should
-/// be idempotent.
-typedef bool Predicate(dynamic value);
-
-/// Performs [action] repeatedly until it either succeeds or [timeout] limit is
-/// reached.
-///
-/// When the retry time out, the last seen error and stack trace are returned in
-/// an error [Future].
-Future<dynamic> retry(
-  Action action,
-  Duration timeout,
-  Duration pauseBetweenRetries, {
-  Predicate predicate,
-}) async {
-  assert(action != null);
-  assert(timeout != null);
-  assert(pauseBetweenRetries != null);
-
-  final Stopwatch sw = stopwatchFactory()..start();
-  dynamic result;
-  dynamic lastError;
-  dynamic lastStackTrace;
-  bool success = false;
-
-  while (!success && sw.elapsed < timeout) {
-    try {
-      result = await action();
-      if (predicate == null || predicate(result))
-        success = true;
-      lastError = null;
-      lastStackTrace = null;
-    } catch(error, stackTrace) {
-      lastError = error;
-      lastStackTrace = stackTrace;
-    }
-
-    if (!success && sw.elapsed < timeout)
-      await new Future<Null>.delayed(pauseBetweenRetries);
-  }
-
-  if (success)
-    return result;
-  else if (lastError != null)
-    return new Future<Null>.error(lastError, lastStackTrace);
-  else
-    return new Future<Null>.error('Retry timed out');
-}
-
-/// A function that produces a [Stopwatch].
-typedef Stopwatch StopwatchFactory();
-
-/// Restores [stopwatchFactory] to the default implementation.
-void restoreStopwatchFactory() {
-  stopwatchFactory = () => new Stopwatch();
-}
-
-/// Used by [retry] as a source of [Stopwatch] implementation.
-StopwatchFactory stopwatchFactory = () => new Stopwatch();

packages/flutter_driver/test/src/retry_test.dart

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'package:test/test.dart';
-import 'package:quiver/time.dart';
-import 'package:quiver/testing/async.dart';
-import 'package:quiver/testing/time.dart';
-
-import 'package:flutter_driver/src/retry.dart';
-
-void main() {
-  group('retry', () {
-    FakeAsync fakeAsync;
-
-    setUp(() {
-      fakeAsync = new FakeAsync();
-      final Clock fakeClock = fakeAsync.getClock(new DateTime.now());
-      stopwatchFactory = () {
-        return new FakeStopwatch(
-          () => fakeClock.now().millisecondsSinceEpoch,
-          1000
-        );
-      };
-    });
-
-    test('retries until succeeds', () {
-      fakeAsync.run((_) {
-        int retryCount = 0;
-
-        expect(
-          retry(
-            () async {
-              retryCount++;
-              if (retryCount < 2) {
-                throw 'error';
-              } else {
-                return retryCount;
-              }
-            },
-            const Duration(milliseconds: 30),
-            const Duration(milliseconds: 10)
-          ),
-          completion(2)
-        );
-
-        fakeAsync.elapse(const Duration(milliseconds: 50));
-
-        // Check that we didn't retry more times than necessary
-        expect(retryCount, 2);
-      });
-    });
-
-    test('obeys predicates', () {
-      fakeAsync.run((_) {
-        int retryCount = 0;
-
-        expect(
-          // The predicate requires that the returned value is 2, so we expect
-          // that `retry` keeps trying until the counter reaches 2.
-          retry(
-            () async => retryCount++,
-            const Duration(milliseconds: 30),
-            const Duration(milliseconds: 10),
-            predicate: (int value) => value == 2
-          ),
-          completion(2)
-        );
-
-        fakeAsync.elapse(const Duration(milliseconds: 50));
-      });
-    });
-
-    test('times out returning last error', () async {
-      fakeAsync.run((_) {
-        bool timedOut = false;
-        int retryCount = 0;
-        dynamic lastError;
-        dynamic lastStackTrace;
-
-        retry(
-          () {
-            retryCount++;
-            throw 'error';
-          },
-          const Duration(milliseconds: 7),
-          const Duration(milliseconds: 2)
-        ).catchError((dynamic error, dynamic stackTrace) {
-          timedOut = true;
-          lastError = error;
-          lastStackTrace = stackTrace;
-        });
-
-        fakeAsync.elapse(const Duration(milliseconds: 10));
-
-        expect(timedOut, isTrue);
-        expect(lastError, 'error');
-        expect(lastStackTrace, isNotNull);
-        expect(retryCount, 4);
-      });
-    });
-  });
-}