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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"math"
)
func main() {
TestMinFloat()
TestMaxFloat()
TestMinMaxInt()
TestMinMaxUint8()
TestMinMaxString()
}
func errorf(format string, args ...any) { panic(fmt.Sprintf(format, args...)) }
func fatalf(format string, args ...any) { panic(fmt.Sprintf(format, args...)) }
// derived from $GOROOT/src/runtime/minmax_test.go
var (
zero = math.Copysign(0, +1)
negZero = math.Copysign(0, -1)
inf = math.Inf(+1)
negInf = math.Inf(-1)
nan = math.NaN()
)
var tests = []struct{ min, max float64 }{
{1, 2},
{-2, 1},
{negZero, zero},
{zero, inf},
{negInf, zero},
{negInf, inf},
{1, inf},
{negInf, 1},
}
var all = []float64{1, 2, -1, -2, zero, negZero, inf, negInf, nan}
func eq(x, y float64) bool {
return x == y && math.Signbit(x) == math.Signbit(y)
}
func TestMinFloat() {
for _, tt := range tests {
if z := min(tt.min, tt.max); !eq(z, tt.min) {
errorf("min(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.min)
}
if z := min(tt.max, tt.min); !eq(z, tt.min) {
errorf("min(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.min)
}
}
for _, x := range all {
if z := min(nan, x); !math.IsNaN(z) {
errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
}
if z := min(x, nan); !math.IsNaN(z) {
errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
}
}
}
func TestMaxFloat() {
for _, tt := range tests {
if z := max(tt.min, tt.max); !eq(z, tt.max) {
errorf("max(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.max)
}
if z := max(tt.max, tt.min); !eq(z, tt.max) {
errorf("max(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.max)
}
}
for _, x := range all {
if z := max(nan, x); !math.IsNaN(z) {
errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
}
if z := max(x, nan); !math.IsNaN(z) {
errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
}
}
}
// testMinMax tests that min/max behave correctly on every pair of
// values in vals.
//
// vals should be a sequence of values in strictly ascending order.
func testMinMax[T int | uint8 | string](vals ...T) {
for i, x := range vals {
for _, y := range vals[i+1:] {
if !(x < y) {
fatalf("values out of order: !(%v < %v)", x, y)
}
if z := min(x, y); z != x {
errorf("min(%v, %v) = %v, want %v", x, y, z, x)
}
if z := min(y, x); z != x {
errorf("min(%v, %v) = %v, want %v", y, x, z, x)
}
if z := max(x, y); z != y {
errorf("max(%v, %v) = %v, want %v", x, y, z, y)
}
if z := max(y, x); z != y {
errorf("max(%v, %v) = %v, want %v", y, x, z, y)
}
}
}
}
func TestMinMaxInt() { testMinMax[int](-7, 0, 9) }
func TestMinMaxUint8() { testMinMax[uint8](0, 1, 2, 4, 7) }
func TestMinMaxString() { testMinMax[string]("a", "b", "c") }
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