[web] Update the within() matcher to be more useful

lib/web_ui/test/engine/canvas_test.dart

@@ -11,6 +11,8 @@ import 'package:ui/src/engine.dart';
 
 import 'package:ui/ui.dart' as ui;
 
+import '../matchers.dart';
+
 void main() {
   internalBootstrapBrowserTest(() => testMain);
 }
@@ -31,7 +33,7 @@ void runCanvasTests({required bool deviceClipRoundsOut}) {
       expect(value.length, equals(16));
       for (int r = 0; r < 4; r++) {
         for (int c = 0; c < 4; c++) {
-          expect(value[r*4 + c], closeTo(expected[r*4 + c], 1e-10));
+          expect(value[r*4 + c], within(from: expected[r*4 + c]));
         }
       }
     }

lib/web_ui/test/geometry_test.dart

@@ -13,6 +13,8 @@ import 'package:test/test.dart';
 
 import 'package:ui/ui.dart';
 
+import 'matchers.dart';
+
 void main() {
   internalBootstrapBrowserTest(() => testMain);
 }
@@ -31,34 +33,32 @@ void testMain() {
   });
   test('Offset.fromDirection', () {
     expect(Offset.fromDirection(0.0, 0.0), const Offset(0.0, 0.0));
-    expect(Offset.fromDirection(pi / 2.0).dx,
-        closeTo(0.0, 1e-12)); // aah, floating point math. i love you so.
-    expect(Offset.fromDirection(pi / 2.0).dy, 1.0);
-    expect(Offset.fromDirection(-pi / 2.0).dx, closeTo(0.0, 1e-12));
-    expect(Offset.fromDirection(-pi / 2.0).dy, -1.0);
+     // aah, floating point math. i love you so.
+    expect(Offset.fromDirection(pi / 2.0), within(from: const Offset(0.0, 1.0)));
+    expect(Offset.fromDirection(-pi / 2.0), within(from: const Offset(0.0, -1.0)));
     expect(Offset.fromDirection(0.0), const Offset(1.0, 0.0));
-    expect(Offset.fromDirection(pi / 4.0).dx,
-        closeTo(1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(pi / 4.0).dy,
-        closeTo(1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(-pi / 4.0).dx,
-        closeTo(1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(-pi / 4.0).dy,
-        closeTo(-1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(pi).dx, -1.0);
-    expect(Offset.fromDirection(pi).dy, closeTo(0.0, 1e-12));
-    expect(Offset.fromDirection(pi * 3.0 / 4.0).dx,
-        closeTo(-1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(pi * 3.0 / 4.0).dy,
-        closeTo(1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(-pi * 3.0 / 4.0).dx,
-        closeTo(-1.0 / math.sqrt(2.0), 1e-12));
-    expect(Offset.fromDirection(-pi * 3.0 / 4.0).dy,
-        closeTo(-1.0 / math.sqrt(2.0), 1e-12));
+    expect(
+      Offset.fromDirection(pi / 4.0),
+      within(from: Offset(1.0 / math.sqrt(2.0), 1.0 / math.sqrt(2.0))),
+    );
+    expect(
+      Offset.fromDirection(-pi / 4.0),
+      within(from: Offset(1.0 / math.sqrt(2.0), -1.0 / math.sqrt(2.0))),
+    );
+    expect(Offset.fromDirection(pi), within(from: const Offset(-1.0, 0.0)));
+    expect(
+      Offset.fromDirection(pi * 3.0 / 4.0),
+      within(from: Offset(-1.0 / math.sqrt(2.0), 1.0 / math.sqrt(2.0))),
+    );
+    expect(
+      Offset.fromDirection(-pi * 3.0 / 4.0),
+      within(from: Offset(-1.0 / math.sqrt(2.0), -1.0 / math.sqrt(2.0))),
+    );
     expect(Offset.fromDirection(0.0, 2.0), const Offset(2.0, 0.0));
     expect(
-        Offset.fromDirection(pi / 6, 2.0).dx, closeTo(math.sqrt(3.0), 1e-12));
-    expect(Offset.fromDirection(pi / 6, 2.0).dy, closeTo(1.0, 1e-12));
+      Offset.fromDirection(pi / 6, 2.0),
+      within(from: Offset(math.sqrt(3.0), 1.0)),
+    );
   });
   test('Size.aspectRatio', () {
     expect(const Size(0.0, 0.0).aspectRatio, 0.0);

lib/web_ui/test/lerp_test.dart

@@ -7,12 +7,7 @@ import 'package:test/test.dart';
 
 import 'package:ui/ui.dart';
 
-/// The epsilon of tolerable double precision error.
-///
-/// This is used in various places in the framework to allow for floating point
-/// precision loss in calculations. Differences below this threshold are safe
-/// to disregard.
-const double precisionErrorTolerance = 1e-10;
+import 'matchers.dart';
 
 void main() {
   internalBootstrapBrowserTest(() => testMain);
@@ -31,19 +26,19 @@ void testMain() {
   });
 
   test('lerpDouble should treat a null input as 0 if the other input is non-null', () {
-    expect(lerpDouble(null, 10.0, 0.25), closeTo(2.5, precisionErrorTolerance));
-    expect(lerpDouble(10.0, null, 0.25), closeTo(7.5, precisionErrorTolerance));
+    expect(lerpDouble(null, 10.0, 0.25), within(from: 2.5));
+    expect(lerpDouble(10.0, null, 0.25), within(from: 7.5));
 
-    expect(lerpDouble(null, 10, 0.25), closeTo(2.5, precisionErrorTolerance));
-    expect(lerpDouble(10, null, 0.25), closeTo(7.5, precisionErrorTolerance));
+    expect(lerpDouble(null, 10, 0.25), within(from: 2.5));
+    expect(lerpDouble(10, null, 0.25), within(from: 7.5));
   });
 
   test('lerpDouble should handle interpolation values < 0.0', () {
-    expect(lerpDouble(0.0, 10.0, -5.0), closeTo(-50.0, precisionErrorTolerance));
-    expect(lerpDouble(10.0, 0.0, -5.0), closeTo(60.0, precisionErrorTolerance));
+    expect(lerpDouble(0.0, 10.0, -5.0), within(from: -50.0));
+    expect(lerpDouble(10.0, 0.0, -5.0), within(from: 60.0));
 
-    expect(lerpDouble(0, 10, -5), closeTo(-50, precisionErrorTolerance));
-    expect(lerpDouble(10, 0, -5), closeTo(60, precisionErrorTolerance));
+    expect(lerpDouble(0, 10, -5), within(from: -50));
+    expect(lerpDouble(10, 0, -5), within(from: 60));
   });
 
   test('lerpDouble should return the start value at 0.0', () {
@@ -55,17 +50,17 @@ void testMain() {
   });
 
   test('lerpDouble should interpolate between two values', () {
-    expect(lerpDouble(0.0, 10.0, 0.25), closeTo(2.5, precisionErrorTolerance));
-    expect(lerpDouble(10.0, 0.0, 0.25), closeTo(7.5, precisionErrorTolerance));
+    expect(lerpDouble(0.0, 10.0, 0.25), within(from: 2.5));
+    expect(lerpDouble(10.0, 0.0, 0.25), within(from: 7.5));
 
-    expect(lerpDouble(0, 10, 0.25), closeTo(2.5, precisionErrorTolerance));
-    expect(lerpDouble(10, 0, 0.25), closeTo(7.5, precisionErrorTolerance));
+    expect(lerpDouble(0, 10, 0.25), within(from: 2.5));
+    expect(lerpDouble(10, 0, 0.25), within(from: 7.5));
 
     // Exact answer: 20.0 - 1.0e-29
-    expect(lerpDouble(10.0, 1.0e30, 1.0e-29), closeTo(20.0, precisionErrorTolerance));
+    expect(lerpDouble(10.0, 1.0e30, 1.0e-29), within(from: 20.0));
 
     // Exact answer: 5.0 + 5.0e29
-    expect(lerpDouble(10.0, 1.0e30, 0.5), closeTo(5.0e29, precisionErrorTolerance));
+    expect(lerpDouble(10.0, 1.0e30, 0.5), within(from: 5.0e29));
   });
 
   test('lerpDouble should return the end value at 1.0', () {
@@ -80,11 +75,11 @@ void testMain() {
   });
 
   test('lerpDouble should handle interpolation values > 1.0', () {
-    expect(lerpDouble(0.0, 10.0, 5.0), closeTo(50.0, precisionErrorTolerance));
-    expect(lerpDouble(10.0, 0.0, 5.0), closeTo(-40.0, precisionErrorTolerance));
+    expect(lerpDouble(0.0, 10.0, 5.0), within(from: 50.0));
+    expect(lerpDouble(10.0, 0.0, 5.0), within(from: -40.0));
 
-    expect(lerpDouble(0, 10, 5), closeTo(50, precisionErrorTolerance));
-    expect(lerpDouble(10, 0, 5), closeTo(-40, precisionErrorTolerance));
+    expect(lerpDouble(0, 10, 5), within(from: 50));
+    expect(lerpDouble(10, 0, 5), within(from: -40));
   });
 
   test('lerpDouble should return input value in all cases if begin/end are equal', () {

lib/web_ui/test/matchers.dart

@@ -15,6 +15,13 @@ import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
 import 'package:ui/ui.dart';
 
+/// The epsilon of tolerable double precision error.
+///
+/// This is used in various places in the framework to allow for floating point
+/// precision loss in calculations. Differences below this threshold are safe
+/// to disregard.
+const double precisionErrorTolerance = 1e-10;
+
 /// Enumerates all persisted surfaces in the tree rooted at [root].
 ///
 /// If [root] is `null` returns all surfaces from the last rendered scene.
@@ -60,7 +67,7 @@ Iterable<PersistedOffset> enumerateOffsets([PersistedSurface? root]) {
 ///
 /// This makes it useful for comparing numbers, [Color]s, [Offset]s and other
 /// sets of value for which a metric space is defined.
-typedef DistanceFunction<T> = num Function(T a, T b);
+typedef DistanceFunction<T> = double Function(T a, T b);
 
 /// The type of a union of instances of [DistanceFunction<T>] for various types
 /// T.
@@ -85,7 +92,7 @@ const Map<Type, AnyDistanceFunction> _kStandardDistanceFunctions =
   Size: _sizeDistance,
 };
 
-int _intDistance(int a, int b) => (b - a).abs();
+double _intDistance(int a, int b) => (b - a).abs().toDouble();
 double _doubleDistance(double a, double b) => (b - a).abs();
 double _offsetDistance(Offset a, Offset b) => (b - a).distance;
 
@@ -131,8 +138,8 @@ double _sizeDistance(Size a, Size b) {
 ///    [double]s and has an optional `epsilon` parameter.
 ///  * [closeTo], which specializes in numbers only.
 Matcher within<T>({
-  required num distance,
   required T from,
+  double distance = precisionErrorTolerance,
   DistanceFunction<T>? distanceFunction,
 }) {
   distanceFunction ??= _kStandardDistanceFunctions[T] as DistanceFunction<T>?;
@@ -152,7 +159,7 @@ class _IsWithinDistance<T> extends Matcher {
 
   final DistanceFunction<T> distanceFunction;
   final T value;
-  final num epsilon;
+  final double epsilon;
 
   @override
   bool matches(Object? object, Map<dynamic, dynamic> matchState) {
@@ -163,7 +170,7 @@ class _IsWithinDistance<T> extends Matcher {
       return true;
     }
     final T test = object;
-    final num distance = distanceFunction(test, value);
+    final double distance = distanceFunction(test, value);
     if (distance < 0) {
       throw ArgumentError(
           'Invalid distance function was used to compare a ${value.runtimeType} '