Invalid Curve transform parameter should assert (#7340)

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

@@ -16,7 +16,8 @@ abstract class Curve {
 
   /// Returns the value of the curve at point `t`.
   ///
-  /// The value of `t` must be between 0.0 and 1.0, inclusive.
+  /// The value of `t` must be between 0.0 and 1.0, inclusive. Subclasses should
+  /// assert that this is true.
   double transform(double t);
 
   /// Returns a new curve that is the reversed inversion of this one.
@@ -54,6 +55,7 @@ class SawTooth extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     if (t == 1.0)
       return 1.0;
     t *= count;
@@ -84,6 +86,7 @@ class Interval extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     assert(begin >= 0.0);
     assert(begin <= 1.0);
     assert(end >= 0.0);
@@ -119,6 +122,7 @@ class Threshold extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     assert(threshold >= 0.0);
     assert(threshold <= 1.0);
     if (t == 0.0 || t == 1.0)
@@ -180,6 +184,7 @@ class Cubic extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     double start = 0.0;
     double end = 1.0;
     while (true) {
@@ -235,6 +240,7 @@ class _DecelerateCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     // Intended to match the behavior of:
     // https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/view/animation/DecelerateInterpolator.java
     // ...as of December 2016.
@@ -268,6 +274,7 @@ class _BounceInCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     return 1.0 - _bounce(1.0 - t);
   }
 }
@@ -280,6 +287,7 @@ class _BounceOutCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     return _bounce(t);
   }
 }
@@ -292,6 +300,7 @@ class _BounceInOutCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     if (t < 0.5)
       return (1.0 - _bounce(1.0 - t)) * 0.5;
     else
@@ -314,6 +323,7 @@ class ElasticInCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     double s = period / 4.0;
     t = t - 1.0;
     return -math.pow(2.0, 10.0 * t) * math.sin((t - s) * (math.PI * 2.0) / period);
@@ -337,6 +347,7 @@ class ElasticOutCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     double s = period / 4.0;
     return math.pow(2.0, -10 * t) * math.sin((t - s) * (math.PI * 2.0) / period) + 1.0;
   }
@@ -359,6 +370,7 @@ class ElasticInOutCurve extends Curve {
 
   @override
   double transform(double t) {
+    assert(t >= 0.0 && t <= 1.0);
     double s = period / 4.0;
     t = 2.0 * t - 1.0;
     if (t < 0.0)

packages/flutter/test/animation/curves_test.dart

@@ -103,4 +103,37 @@ void main() {
     double d2 = Curves.decelerate.transform(1.0) - Curves.decelerate.transform(0.8);
     expect(d2, lessThan(d1));
   });
+
+  test('Invalid transform parameter should assert', () {
+    expect(() => const SawTooth(2).transform(-0.0001), throws);
+    expect(() => const SawTooth(2).transform(1.0001), throws);
+
+    expect(() => const Interval(0.0, 1.0).transform(-0.0001), throws);
+    expect(() => const Interval(0.0, 1.0).transform(1.0001), throws);
+
+    expect(() => const Threshold(0.5).transform(-0.0001), throws);
+    expect(() => const Threshold(0.5).transform(1.0001), throws);
+
+    expect(() => const ElasticInCurve().transform(-0.0001), throws);
+    expect(() => const ElasticInCurve().transform(1.0001), throws);
+
+    expect(() => const ElasticOutCurve().transform(-0.0001), throws);
+    expect(() => const ElasticOutCurve().transform(1.0001), throws);
+
+    expect(() => const Cubic(0.42, 0.0, 0.58, 1.0).transform(-0.0001), throws);
+    expect(() => const Cubic(0.42, 0.0, 0.58, 1.0).transform(1.0001), throws);
+
+    expect(() => Curves.decelerate.transform(-0.0001), throws);
+    expect(() => Curves.decelerate.transform(1.0001), throws);
+
+    expect(() => Curves.bounceIn.transform(-0.0001), throws);
+    expect(() => Curves.bounceIn.transform(1.0001), throws);
+
+    expect(() => Curves.bounceOut.transform(-0.0001), throws);
+    expect(() => Curves.bounceOut.transform(1.0001), throws);
+
+    expect(() => Curves.bounceInOut.transform(-0.0001), throws);
+    expect(() => Curves.bounceInOut.transform(1.0001), throws);
+  });
+
 }