Improved debug validations. (#5822)

This commit renames all debugAssertValid methods to
debugAssertIsValid and assert BoxConstaints validity in
constructors. Fixes #5807.

packages/flutter/lib/src/painting/box_painter.dart

@@ -1045,10 +1045,10 @@ class BoxDecoration extends Decoration {
   });
 
   @override
-  bool debugAssertValid() {
+  bool debugAssertIsValid() {
     assert(shape != BoxShape.circle ||
            borderRadius == null); // Can't have a border radius if you're a circle.
-    return super.debugAssertValid();
+    return super.debugAssertIsValid();
   }
 
   /// The color to fill in the background of the box.

packages/flutter/lib/src/painting/decoration.dart

@@ -33,9 +33,9 @@ abstract class Decoration {
   ///
   /// This is intended to be used as follows:
   /// ```dart
-  ///   assert(myDecoration.debugAssertValid());
+  ///   assert(myDecoration.debugAssertIsValid());
   /// ```
-  bool debugAssertValid() => true;
+  bool debugAssertIsValid() => true;
 
   /// Returns the insets to apply when using this decoration on a box
   /// that has contents, so that the contents do not overlap the edges

packages/flutter/lib/src/painting/flutter_logo.dart

@@ -97,7 +97,7 @@ class FlutterLogoDecoration extends Decoration {
   bool get _inTransition => _opacity != 1.0 || (_position != -1.0 && _position != 0.0 && _position != 1.0);
 
   @override
-  bool debugAssertValid() {
+  bool debugAssertIsValid() {
     assert(swatch != null
         && swatch[_lightShade] != null
         && swatch[_darkShade] != null
@@ -121,8 +121,8 @@ class FlutterLogoDecoration extends Decoration {
   ///
   /// See also [Decoration.lerp].
   static FlutterLogoDecoration lerp(FlutterLogoDecoration a, FlutterLogoDecoration b, double t) {
-    assert(a == null || a.debugAssertValid());
-    assert(b == null || b.debugAssertValid());
+    assert(a == null || a.debugAssertIsValid());
+    assert(b == null || b.debugAssertIsValid());
     if (a == null && b == null)
       return null;
     if (a == null) {
@@ -166,19 +166,19 @@ class FlutterLogoDecoration extends Decoration {
 
   @override
   FlutterLogoDecoration lerpFrom(Decoration a, double t) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     if (a is! FlutterLogoDecoration)
       return lerp(null, this, t);
-    assert(a.debugAssertValid);
+    assert(a.debugAssertIsValid);
     return lerp(a, this, t);
   }
 
   @override
   FlutterLogoDecoration lerpTo(Decoration b, double t) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     if (b is! FlutterLogoDecoration)
       return lerp(this, null, t);
-    assert(b.debugAssertValid());
+    assert(b.debugAssertIsValid());
     return lerp(this, b, t);
   }
 
@@ -188,13 +188,13 @@ class FlutterLogoDecoration extends Decoration {
 
   @override
   BoxPainter createBoxPainter([VoidCallback onChanged]) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     return new _FlutterLogoPainter(this);
   }
 
   @override
   bool operator ==(dynamic other) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     if (identical(this, other))
       return true;
     if (other is! FlutterLogoDecoration)
@@ -209,7 +209,7 @@ class FlutterLogoDecoration extends Decoration {
 
   @override
   int get hashCode {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     return hashValues(
       swatch[_lightShade],
       swatch[_darkShade],
@@ -233,7 +233,7 @@ class FlutterLogoDecoration extends Decoration {
 class _FlutterLogoPainter extends BoxPainter {
   _FlutterLogoPainter(this._config) : super(null) {
     assert(_config != null);
-    assert(_config.debugAssertValid());
+    assert(_config.debugAssertIsValid());
     _prepareText();
   }
 

packages/flutter/lib/src/painting/text_painter.dart

@@ -34,7 +34,7 @@ class TextPainter {
     TextSpan text,
     TextAlign textAlign
   }) : _text = text, _textAlign = textAlign {
-    assert(text == null || text.debugAssertValid());
+    assert(text == null || text.debugAssertIsValid());
   }
 
   ui.Paragraph _paragraph;
@@ -44,7 +44,7 @@ class TextPainter {
   TextSpan get text => _text;
   TextSpan _text;
   set text(TextSpan value) {
-    assert(value == null || value.debugAssertValid());
+    assert(value == null || value.debugAssertIsValid());
     if (_text == value)
       return;
     _text = value;

packages/flutter/lib/src/painting/text_span.dart

@@ -94,7 +94,7 @@ class TextSpan {
   /// [TextPainter] class to paint [TextSpan] objects onto [Canvas]
   /// objects.
   void build(ui.ParagraphBuilder builder) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     final bool hasStyle = style != null;
     if (hasStyle)
       builder.pushStyle(style.textStyle);
@@ -127,7 +127,7 @@ class TextSpan {
 
   /// Returns the text span that contains the given position in the text.
   TextSpan getSpanForPosition(TextPosition position) {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     TextAffinity affinity = position.affinity;
     int targetOffset = position.offset;
     int offset = 0;
@@ -151,7 +151,7 @@ class TextSpan {
   ///
   /// Styles are not honored in this process.
   String toPlainText() {
-    assert(debugAssertValid());
+    assert(debugAssertIsValid());
     StringBuffer buffer = new StringBuffer();
     visitTextSpan((TextSpan span) {
       buffer.write(span.text);
@@ -188,9 +188,9 @@ class TextSpan {
   ///
   /// This is intended to be used as follows:
   /// ```dart
-  ///   assert(myTextSpan.debugAssertValid());
+  ///   assert(myTextSpan.debugAssertIsValid());
   /// ```
-  bool debugAssertValid() {
+  bool debugAssertIsValid() {
     assert(() {
       if (!visitTextSpan((TextSpan span) {
         if (span.children != null) {

packages/flutter/lib/src/rendering/paragraph.dart

@@ -35,7 +35,7 @@ class RenderParagraph extends RenderBox {
        _overflow = overflow,
        _textPainter = new TextPainter(text: text, textAlign: textAlign) {
     assert(text != null);
-    assert(text.debugAssertValid());
+    assert(text.debugAssertIsValid());
     assert(overflow != null);
     assert(softWrap != null);
   }

packages/flutter/lib/src/widgets/basic.dart

@@ -794,6 +794,7 @@ class ConstrainedBox extends SingleChildRenderObjectWidget {
     Widget child
   }) : super(key: key, child: child) {
     assert(constraints != null);
+    assert(constraints.debugAssertIsValid());
   }
 
   /// The additional constraints to impose on the child.

packages/flutter/lib/src/widgets/container.dart

@@ -94,7 +94,8 @@ class Container extends StatelessWidget {
        super(key: key) {
     assert(margin == null || margin.isNonNegative);
     assert(padding == null || padding.isNonNegative);
-    assert(decoration == null || decoration.debugAssertValid());
+    assert(decoration == null || decoration.debugAssertIsValid());
+    assert(constraints == null || constraints.debugAssertIsValid());
   }
 
   /// The child contained by the container.

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -235,10 +235,11 @@ class AnimatedContainer extends ImplicitlyAnimatedWidget {
     Curve curve: Curves.linear,
     @required Duration duration
   }) : super(key: key, curve: curve, duration: duration) {
-    assert(decoration == null || decoration.debugAssertValid());
-    assert(foregroundDecoration == null || foregroundDecoration.debugAssertValid());
+    assert(decoration == null || decoration.debugAssertIsValid());
+    assert(foregroundDecoration == null || foregroundDecoration.debugAssertIsValid());
     assert(margin == null || margin.isNonNegative);
     assert(padding == null || padding.isNonNegative);
+    assert(constraints == null || constraints.debugAssertIsValid());
   }
 
   /// The widget below this widget in the tree.