Fix the duration assertion error for the _animateToInternal method and refine...

Fix the duration assertion error for the _animateToInternal method and refine the error description (#71137)

packages/flutter/lib/src/animation/animation_controller.dart

@@ -508,6 +508,17 @@ class AnimationController extends Animation<double>
   /// animation, when `target` is reached, [status] is reported as
   /// [AnimationStatus.completed].
   TickerFuture animateTo(double target, { Duration? duration, Curve curve = Curves.linear }) {
+    assert(() {
+      if (this.duration == null && duration == null) {
+        throw FlutterError(
+          'AnimationController.animateTo() called with no explicit duration and no default duration.\n'
+          'Either the "duration" argument to the animateTo() method should be provided, or the '
+          '"duration" property should be set, either in the constructor or later, before '
+          'calling the animateTo() function.'
+        );
+      }
+      return true;
+    }());
     assert(
       _ticker != null,
       'AnimationController.animateTo() called after AnimationController.dispose()\n'
@@ -530,6 +541,17 @@ class AnimationController extends Animation<double>
   /// animation, when `target` is reached, [status] is reported as
   /// [AnimationStatus.dismissed].
   TickerFuture animateBack(double target, { Duration? duration, Curve curve = Curves.linear }) {
+    assert(() {
+      if (this.duration == null && reverseDuration == null && duration == null) {
+        throw FlutterError(
+          'AnimationController.animateBack() called with no explicit duration and no default duration or reverseDuration.\n'
+          'Either the "duration" argument to the animateBack() method should be provided, or the '
+          '"duration" or "reverseDuration" property should be set, either in the constructor or later, before '
+          'calling the animateBack() function.'
+        );
+      }
+      return true;
+    }());
     assert(
       _ticker != null,
       'AnimationController.animateBack() called after AnimationController.dispose()\n'
@@ -555,17 +577,8 @@ class AnimationController extends Animation<double>
     }
     Duration? simulationDuration = duration;
     if (simulationDuration == null) {
-      assert(() {
-        if ((this.duration == null && _direction == _AnimationDirection.reverse && reverseDuration == null) || this.duration == null) {
-          throw FlutterError(
-            'AnimationController.animateTo() called with no explicit duration and no default duration or reverseDuration.\n'
-            'Either the "duration" argument to the animateTo() method should be provided, or the '
-            '"duration" and/or "reverseDuration" property should be set, either in the constructor or later, before '
-            'calling the animateTo() function.'
-          );
-        }
-        return true;
-      }());
+      assert(!(this.duration == null && _direction == _AnimationDirection.forward));
+      assert(!(this.duration == null && _direction == _AnimationDirection.reverse && reverseDuration == null));
       final double range = upperBound - lowerBound;
       final double remainingFraction = range.isFinite ? (target - _value).abs() / range : 1.0;
       final Duration directionDuration =

packages/flutter/test/animation/animation_controller_test.dart

@@ -929,6 +929,135 @@ void main() {
     tick(const Duration(seconds: 1));
     expect(statuses, <AnimationStatus>[AnimationStatus.reverse]);
   });
+
+  test('AnimateBack can runs successfully with just "reverseDuration" property set', () {
+    final List<AnimationStatus> statuses = <AnimationStatus>[];
+    final AnimationController controller = AnimationController(
+      reverseDuration: const Duration(seconds: 2),
+      vsync: const TestVSync(),
+    )..addStatusListener((AnimationStatus status) {
+      statuses.add(status);
+    });
+
+    controller.animateBack(0.8);
+
+    expect(statuses, <AnimationStatus>[AnimationStatus.reverse]);
+    statuses.clear();
+    tick(const Duration(milliseconds: 0));
+    tick(const Duration(seconds: 2));
+    expect(statuses, <AnimationStatus>[AnimationStatus.dismissed]);
+
+    controller.dispose();
+  });
+
+  group('AnimationController "duration" error test', () {
+    test('AnimationController forward() will throw an error if there is no default duration', () {
+      final AnimationController controller = AnimationController(
+        vsync: const TestVSync(),
+      );
+
+      late FlutterError error;
+      try {
+        controller.forward();
+      } on FlutterError catch (e) {
+        error = e;
+      }
+
+      expect(error, isNotNull);
+      expect(
+        error.toStringDeep(),
+        'FlutterError\n'
+          '   AnimationController.forward() called with no default duration.\n'
+          '   The "duration" property should be set, either in the constructor\n'
+          '   or later, before calling the forward() function.\n'
+      );
+
+      controller.dispose();
+    });
+
+    test('AnimationController animateTo() will throw an error if there is no explicit duration '
+      'and default duration', () {
+      final AnimationController controller = AnimationController(
+        vsync: const TestVSync(),
+      );
+
+      late FlutterError error;
+      try {
+        controller.animateTo(0.8);
+      } on FlutterError catch (e) {
+        error = e;
+      }
+
+      expect(error, isNotNull);
+      expect(
+        error.toStringDeep(),
+        'FlutterError\n'
+          '   AnimationController.animateTo() called with no explicit duration\n'
+          '   and no default duration.\n'
+          '   Either the "duration" argument to the animateTo() method should\n'
+          '   be provided, or the "duration" property should be set, either in\n'
+          '   the constructor or later, before calling the animateTo()\n'
+          '   function.\n'
+      );
+
+      controller.dispose();
+    });
+
+    test('AnimationController reverse() will throw an error if there is no default duration or reverseDuration', () {
+      final AnimationController controller = AnimationController(
+        vsync: const TestVSync(),
+      );
+
+      late FlutterError error;
+      try {
+        controller.reverse();
+      } on FlutterError catch (e) {
+        error = e;
+      }
+
+      expect(error, isNotNull);
+      expect(
+        error.toStringDeep(),
+        'FlutterError\n'
+          '   AnimationController.reverse() called with no default duration or\n'
+          '   reverseDuration.\n'
+          '   The "duration" or "reverseDuration" property should be set,\n'
+          '   either in the constructor or later, before calling the reverse()\n'
+          '   function.\n'
+      );
+
+      controller.dispose();
+    });
+
+    test('AnimationController animateBack() will throw an error if there is no explicit duration and '
+      'no default duration or reverseDuration', () {
+      final AnimationController controller = AnimationController(
+        vsync: const TestVSync(),
+      );
+
+      late FlutterError error;
+      try {
+        controller.animateBack(0.8);
+      } on FlutterError catch (e) {
+        error = e;
+      }
+
+      expect(error, isNotNull);
+      expect(
+        error.toStringDeep(),
+        'FlutterError\n'
+          '   AnimationController.animateBack() called with no explicit\n'
+          '   duration and no default duration or reverseDuration.\n'
+          '   Either the "duration" argument to the animateBack() method should\n'
+          '   be provided, or the "duration" or "reverseDuration" property\n'
+          '   should be set, either in the constructor or later, before calling\n'
+          '   the animateBack() function.\n'
+      );
+
+      controller.dispose();
+    });
+  });
+
 }
 
 class TestSimulation extends Simulation {