apply prefer_asserts_in_initializer_list lint (#10483)

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

@@ -115,12 +115,11 @@ class AnimationController extends Animation<double>
     this.lowerBound: 0.0,
     this.upperBound: 1.0,
     @required TickerProvider vsync,
-  }) {
-    assert(lowerBound != null);
-    assert(upperBound != null);
-    assert(upperBound >= lowerBound);
-    assert(vsync != null);
-    _direction = _AnimationDirection.forward;
+  }) : assert(lowerBound != null),
+       assert(upperBound != null),
+       assert(upperBound >= lowerBound),
+       assert(vsync != null),
+       _direction = _AnimationDirection.forward {
     _ticker = vsync.createTicker(_tick);
     _internalSetValue(value ?? lowerBound);
   }
@@ -146,11 +145,11 @@ class AnimationController extends Animation<double>
     this.duration,
     this.debugLabel,
     @required TickerProvider vsync,
-  }) : lowerBound = double.NEGATIVE_INFINITY,
-       upperBound = double.INFINITY {
-    assert(value != null);
-    assert(vsync != null);
-    _direction = _AnimationDirection.forward;
+  }) : assert(value != null),
+       assert(vsync != null),
+       lowerBound = double.NEGATIVE_INFINITY,
+       upperBound = double.INFINITY,
+       _direction = _AnimationDirection.forward {
     _ticker = vsync.createTicker(_tick);
     _internalSetValue(value);
   }
@@ -496,11 +495,10 @@ class AnimationController extends Animation<double>
 
 class _InterpolationSimulation extends Simulation {
   _InterpolationSimulation(this._begin, this._end, Duration duration, this._curve)
-    : _durationInSeconds = duration.inMicroseconds / Duration.MICROSECONDS_PER_SECOND {
-    assert(_durationInSeconds > 0.0);
-    assert(_begin != null);
-    assert(_end != null);
-  }
+    : assert(_begin != null),
+      assert(_end != null),
+      assert(duration != null && duration.inMicroseconds > 0),
+      _durationInSeconds = duration.inMicroseconds / Duration.MICROSECONDS_PER_SECOND;
 
   final double _durationInSeconds;
   final double _begin;

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

@@ -247,9 +247,8 @@ class ReverseAnimation extends Animation<double>
   /// Creates a reverse animation.
   ///
   /// The parent argument must not be null.
-  ReverseAnimation(this.parent) {
-    assert(parent != null);
-  }
+  ReverseAnimation(this.parent)
+    : assert(parent != null);
 
   /// The animation whose value and direction this animation is reversing.
   final Animation<double> parent;
@@ -331,9 +330,8 @@ class CurvedAnimation extends Animation<double> with AnimationWithParentMixin<do
     @required this.parent,
     @required this.curve,
     this.reverseCurve
-  }) {
-    assert(parent != null);
-    assert(curve != null);
+  }) : assert(parent != null),
+       assert(curve != null) {
     _updateCurveDirection(parent.status);
     parent.addStatusListener(_updateCurveDirection);
   }
@@ -441,8 +439,8 @@ class TrainHoppingAnimation extends Animation<double>
   ///
   /// The current train argument must not be null but the next train argument
   /// can be null.
-  TrainHoppingAnimation(this._currentTrain, this._nextTrain, { this.onSwitchedTrain }) {
-    assert(_currentTrain != null);
+  TrainHoppingAnimation(this._currentTrain, this._nextTrain, { this.onSwitchedTrain })
+    : assert(_currentTrain != null) {
     if (_nextTrain != null) {
       if (_currentTrain.value > _nextTrain.value) {
         _mode = _TrainHoppingMode.maximize;
@@ -552,10 +550,8 @@ abstract class CompoundAnimation<T> extends Animation<T>
   CompoundAnimation({
     @required this.first,
     @required this.next,
-  }) {
-    assert(first != null);
-    assert(next != null);
-  }
+  }) : assert(first != null),
+       assert(next != null);
 
   /// The first sub-animation. Its status takes precedence if neither are
   /// animating.

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

@@ -291,9 +291,8 @@ class CurveTween extends Animatable<double> {
   /// Creates a curve tween.
   ///
   /// The [curve] argument must not be null.
-  CurveTween({ @required this.curve }) {
-    assert(curve != null);
-  }
+  CurveTween({ @required this.curve })
+    : assert(curve != null);
 
   /// The curve to use when transforming the value of the animation.
   Curve curve;

packages/flutter/lib/src/cupertino/bottom_tab_bar.dart

@@ -41,12 +41,11 @@ class CupertinoTabBar extends StatelessWidget {
     this.activeColor: CupertinoColors.activeBlue,
     this.inactiveColor: CupertinoColors.inactiveGray,
     this.iconSize: 24.0,
-  }) : super(key: key) {
-    assert(items != null);
-    assert(items.length >= 2);
-    assert(0 <= currentIndex && currentIndex < items.length);
-    assert(iconSize != null);
-  }
+  }) : assert(items != null),
+       assert(items.length >= 2),
+       assert(0 <= currentIndex && currentIndex < items.length),
+       assert(iconSize != null),
+       super(key: key);
 
   /// The interactive items laid out within the bottom navigation bar.
   final List<BottomNavigationBarItem> items;

packages/flutter/lib/src/cupertino/page.dart

@@ -25,7 +25,7 @@ final FractionalOffsetTween _kBottomUpTween = new FractionalOffsetTween(
   end: FractionalOffset.topLeft,
 );
 
-// Custom decoration from no shadow to page shadow mimicking iOS page 
+// Custom decoration from no shadow to page shadow mimicking iOS page
 // transitions using gradients.
 final DecorationTween _kGradientShadowTween = new DecorationTween(
   begin: _CupertinoEdgeShadowDecoration.none, // No decoration initially.
@@ -36,27 +36,27 @@ final DecorationTween _kGradientShadowTween = new DecorationTween(
       end: FractionalOffset.topRight,
       // Eyeballed gradient used to mimic a drop shadow on the left side only.
       colors: const <Color>[
-        const Color(0x00000000), 
+        const Color(0x00000000),
         const Color(0x04000000),
         const Color(0x12000000),
         const Color(0x38000000)
       ],
       stops: const <double>[0.0, 0.3, 0.6, 1.0],
-    ), 
+    ),
   ),
 );
 
-/// A custom [Decoration] used to paint an extra shadow on the left edge of the 
-/// box it's decorating. It's like a [BoxDecoration] with only a gradient except 
+/// A custom [Decoration] used to paint an extra shadow on the left edge of the
+/// box it's decorating. It's like a [BoxDecoration] with only a gradient except
 /// it paints to the left of the box instead of behind the box.
 class _CupertinoEdgeShadowDecoration extends Decoration {
   const _CupertinoEdgeShadowDecoration({ this.edgeGradient });
 
   /// A Decoration with no decorating properties.
-  static const _CupertinoEdgeShadowDecoration none = 
+  static const _CupertinoEdgeShadowDecoration none =
       const _CupertinoEdgeShadowDecoration();
 
-  /// A gradient to draw to the left of the box being decorated. 
+  /// A gradient to draw to the left of the box being decorated.
   /// FractionalOffsets are relative to the original box translated one box
   /// width to the left.
   final LinearGradient edgeGradient;
@@ -65,8 +65,8 @@ class _CupertinoEdgeShadowDecoration extends Decoration {
   ///
   /// See also [Decoration.lerp].
   static _CupertinoEdgeShadowDecoration lerp(
-    _CupertinoEdgeShadowDecoration a, 
-    _CupertinoEdgeShadowDecoration b, 
+    _CupertinoEdgeShadowDecoration a,
+    _CupertinoEdgeShadowDecoration b,
     double t
   ) {
     if (a == null && b == null)
@@ -89,7 +89,7 @@ class _CupertinoEdgeShadowDecoration extends Decoration {
       return _CupertinoEdgeShadowDecoration.lerp(this, null, t);
     return _CupertinoEdgeShadowDecoration.lerp(this, b, t);
   }
-  
+
   @override
   _CupertinoEdgeShadowPainter createBoxPainter([VoidCallback onChanged]) {
     return new _CupertinoEdgeShadowPainter(this, onChanged);
@@ -114,7 +114,7 @@ class _CupertinoEdgeShadowDecoration extends Decoration {
 /// A [BoxPainter] used to draw the page transition shadow using gradients.
 class _CupertinoEdgeShadowPainter extends BoxPainter {
   _CupertinoEdgeShadowPainter(
-    @required this._decoration, 
+    @required this._decoration,
     VoidCallback onChange
   ) : assert(_decoration != null),
       super(onChange);
@@ -126,9 +126,9 @@ class _CupertinoEdgeShadowPainter extends BoxPainter {
     final LinearGradient gradient = _decoration.edgeGradient;
     if (gradient == null)
       return;
-    // The drawable space for the gradient is a rect with the same size as 
+    // The drawable space for the gradient is a rect with the same size as
     // its parent box one box width to the left of the box.
-    final Rect rect = 
+    final Rect rect =
         (offset & configuration.size).translate(-configuration.size.width, 0.0);
     final Paint paint = new Paint()
       ..shader = gradient.createShader(rect);
@@ -249,9 +249,8 @@ class CupertinoBackGestureController extends NavigationGestureController {
   CupertinoBackGestureController({
     @required NavigatorState navigator,
     @required this.controller,
-  }) : super(navigator) {
-    assert(controller != null);
-  }
+  }) : assert(controller != null),
+       super(navigator);
 
   /// The animation controller that the route uses to drive its transition
   /// animation.

packages/flutter/lib/src/cupertino/slider.dart

@@ -192,11 +192,11 @@ class _RenderCupertinoSlider extends RenderConstrainedBox implements SemanticsAc
     Color activeColor,
     this.onChanged,
     TickerProvider vsync,
-  }) : _value = value,
+  }) : assert(value != null && value >= 0.0 && value <= 1.0),
+       _value = value,
        _divisions = divisions,
        _activeColor = activeColor,
        super(additionalConstraints: const BoxConstraints.tightFor(width: _kSliderWidth, height: _kSliderHeight)) {
-    assert(value != null && value >= 0.0 && value <= 1.0);
     _drag = new HorizontalDragGestureRecognizer()
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate

packages/flutter/lib/src/cupertino/switch.dart

@@ -141,14 +141,14 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox implements SemanticsAc
     @required Color activeColor,
     ValueChanged<bool> onChanged,
     @required TickerProvider vsync,
-  }) : _value = value,
-        _activeColor = activeColor,
-        _onChanged = onChanged,
-        _vsync = vsync,
-        super(additionalConstraints: const BoxConstraints.tightFor(width: _kSwitchWidth, height: _kSwitchHeight)) {
-    assert(value != null);
-    assert(activeColor != null);
-    assert(vsync != null);
+  }) : assert(value != null),
+       assert(activeColor != null),
+       assert(vsync != null),
+       _value = value,
+       _activeColor = activeColor,
+       _onChanged = onChanged,
+       _vsync = vsync,
+       super(additionalConstraints: const BoxConstraints.tightFor(width: _kSwitchWidth, height: _kSwitchHeight)) {
     _tap = new TapGestureRecognizer()
       ..onTapDown = _handleTapDown
       ..onTap = _handleTap

packages/flutter/lib/src/gestures/drag_details.dart

@@ -20,9 +20,8 @@ class DragDownDetails {
   /// Creates details for a [GestureDragDownCallback].
   ///
   /// The [globalPosition] argument must not be null.
-  DragDownDetails({ this.globalPosition: Offset.zero }) {
-    assert(globalPosition != null);
-  }
+  DragDownDetails({ this.globalPosition: Offset.zero })
+    : assert(globalPosition != null);
 
   /// The global position at which the pointer contacted the screen.
   ///
@@ -53,9 +52,8 @@ class DragStartDetails {
   /// Creates details for a [GestureDragStartCallback].
   ///
   /// The [globalPosition] argument must not be null.
-  DragStartDetails({ this.globalPosition: Offset.zero }) {
-    assert(globalPosition != null);
-  }
+  DragStartDetails({ this.globalPosition: Offset.zero })
+    : assert(globalPosition != null);
 
   /// The global position at which the pointer contacted the screen.
   ///
@@ -99,12 +97,10 @@ class DragUpdateDetails {
     this.delta: Offset.zero,
     this.primaryDelta,
     @required this.globalPosition
-  }) {
-    assert(delta != null);
-    assert(primaryDelta == null
-        || (primaryDelta == delta.dx && delta.dy == 0.0)
-        || (primaryDelta == delta.dy && delta.dx == 0.0));
-  }
+  }) : assert(delta != null),
+       assert(primaryDelta == null
+           || (primaryDelta == delta.dx && delta.dy == 0.0)
+           || (primaryDelta == delta.dy && delta.dx == 0.0));
 
   /// The amount the pointer has moved since the previous update.
   ///
@@ -158,12 +154,10 @@ class DragEndDetails {
   DragEndDetails({
     this.velocity: Velocity.zero,
     this.primaryVelocity,
-  }) {
-    assert(velocity != null);
-    assert(primaryVelocity == null
-        || primaryVelocity == velocity.pixelsPerSecond.dx
-        || primaryVelocity == velocity.pixelsPerSecond.dy);
-  }
+  }) : assert(velocity != null),
+       assert(primaryVelocity == null
+           || primaryVelocity == velocity.pixelsPerSecond.dx
+           || primaryVelocity == velocity.pixelsPerSecond.dy);
 
   /// The velocity the pointer was moving when it stopped contacting the screen.
   ///

packages/flutter/lib/src/gestures/lsq_solver.dart

@@ -75,10 +75,9 @@ class LeastSquaresSolver {
   /// Creates a least-squares solver.
   ///
   /// The [x], [y], and [w] arguments must not be null.
-  LeastSquaresSolver(this.x, this.y, this.w) {
-    assert(x.length == y.length);
-    assert(y.length == w.length);
-  }
+  LeastSquaresSolver(this.x, this.y, this.w)
+    : assert(x.length == y.length),
+      assert(y.length == w.length);
 
   /// The x-coordinates of each data point.
   final List<double> x;

packages/flutter/lib/src/gestures/multidrag.dart

@@ -27,9 +27,8 @@ abstract class MultiDragPointerState {
   /// Creates per-pointer state for a [MultiDragGestureRecognizer].
   ///
   /// The [initialPosition] argument must not be null.
-  MultiDragPointerState(this.initialPosition) {
-    assert(initialPosition != null);
-  }
+  MultiDragPointerState(this.initialPosition)
+    : assert(initialPosition != null);
 
   /// The global coordinates of the pointer when the pointer contacted the screen.
   final Offset initialPosition;
@@ -396,8 +395,9 @@ class VerticalMultiDragGestureRecognizer extends MultiDragGestureRecognizer<_Ver
 }
 
 class _DelayedPointerState extends MultiDragPointerState {
-  _DelayedPointerState(Offset initialPosition, Duration delay) : super(initialPosition) {
-    assert(delay != null);
+  _DelayedPointerState(Offset initialPosition, Duration delay)
+    : assert(delay != null),
+      super(initialPosition) {
     _timer = new Timer(delay, _delayPassed);
   }
 
@@ -481,9 +481,7 @@ class DelayedMultiDragGestureRecognizer extends MultiDragGestureRecognizer<_Dela
   /// can be changed for specific behaviors.
   DelayedMultiDragGestureRecognizer({
     this.delay: kLongPressTimeout
-  }) {
-    assert(delay != null);
-  }
+  }) : assert(delay != null);
 
   /// The amount of time the pointer must remain in the same place for the drag
   /// to be recognized.

packages/flutter/lib/src/gestures/scale.dart

@@ -32,9 +32,8 @@ class ScaleStartDetails {
   /// Creates details for [GestureScaleStartCallback].
   ///
   /// The [focalPoint] argument must not be null.
-  ScaleStartDetails({ this.focalPoint: Offset.zero }) {
-    assert(focalPoint != null);
-  }
+  ScaleStartDetails({ this.focalPoint: Offset.zero })
+    : assert(focalPoint != null);
 
   /// The initial focal point of the pointers in contact with the screen.
   /// Reported in global coordinates.
@@ -50,10 +49,11 @@ class ScaleUpdateDetails {
   ///
   /// The [focalPoint] and [scale] arguments must not be null. The [scale]
   /// argument must be greater than or equal to zero.
-  ScaleUpdateDetails({ this.focalPoint: Offset.zero, this.scale: 1.0 }) {
-    assert(focalPoint != null);
-    assert(scale != null && scale >= 0.0);
-  }
+  ScaleUpdateDetails({
+    this.focalPoint: Offset.zero,
+    this.scale: 1.0,
+  }) : assert(focalPoint != null),
+       assert(scale != null && scale >= 0.0);
 
   /// The focal point of the pointers in contact with the screen. Reported in
   /// global coordinates.
@@ -72,9 +72,8 @@ class ScaleEndDetails {
   /// Creates details for [GestureScaleEndCallback].
   ///
   /// The [velocity] argument must not be null.
-  ScaleEndDetails({ this.velocity: Velocity.zero }) {
-    assert(velocity != null);
-  }
+  ScaleEndDetails({ this.velocity: Velocity.zero })
+    : assert(velocity != null);
 
   /// The velocity of the last pointer to be lifted off of the screen.
   final Velocity velocity;

packages/flutter/lib/src/gestures/tap.dart

@@ -12,9 +12,8 @@ class TapDownDetails {
   /// Creates details for a [GestureTapDownCallback].
   ///
   /// The [globalPosition] argument must not be null.
-  TapDownDetails({ this.globalPosition: Offset.zero }) {
-    assert(globalPosition != null);
-  }
+  TapDownDetails({ this.globalPosition: Offset.zero })
+    : assert(globalPosition != null);
 
   /// The global position at which the pointer contacted the screen.
   final Offset globalPosition;
@@ -32,9 +31,8 @@ class TapUpDetails {
   /// Creates details for a [GestureTapUpCallback].
   ///
   /// The [globalPosition] argument must not be null.
-  TapUpDetails({ this.globalPosition: Offset.zero }) {
-    assert(globalPosition != null);
-  }
+  TapUpDetails({ this.globalPosition: Offset.zero })
+    : assert(globalPosition != null);
 
   /// The global position at which the pointer contacted the screen.
   final Offset globalPosition;