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      1 // Copyright 2017 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 package color
      6 
      7 import (
      8 	"testing"
      9 	"testing/quick"
     10 )
     11 
     12 func TestSqDiff(t *testing.T) {
     13 	// canonical sqDiff implementation
     14 	orig := func(x, y uint32) uint32 {
     15 		var d uint32
     16 		if x > y {
     17 			d = uint32(x - y)
     18 		} else {
     19 			d = uint32(y - x)
     20 		}
     21 		return (d * d) >> 2
     22 	}
     23 	testCases := []uint32{
     24 		0,
     25 		1,
     26 		2,
     27 		0x0fffd,
     28 		0x0fffe,
     29 		0x0ffff,
     30 		0x10000,
     31 		0x10001,
     32 		0x10002,
     33 		0xfffffffd,
     34 		0xfffffffe,
     35 		0xffffffff,
     36 	}
     37 	for _, x := range testCases {
     38 		for _, y := range testCases {
     39 			if got, want := sqDiff(x, y), orig(x, y); got != want {
     40 				t.Fatalf("sqDiff(%#x, %#x): got %d, want %d", x, y, got, want)
     41 			}
     42 		}
     43 	}
     44 	if err := quick.CheckEqual(orig, sqDiff, &quick.Config{MaxCountScale: 10}); err != nil {
     45 		t.Fatal(err)
     46 	}
     47 }
     48