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// Copyright 2010 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 sort_test
import (
"runtime"
. "sort"
"testing"
)
func f(a []int, x int) func(int) bool {
return func(i int) bool {
return a[i] >= x
}
}
var data = []int{0: -10, 1: -5, 2: 0, 3: 1, 4: 2, 5: 3, 6: 5, 7: 7, 8: 11, 9: 100, 10: 100, 11: 100, 12: 1000, 13: 10000}
var tests = []struct {
name string
n int
f func(int) bool
i int
}{
{"empty", 0, nil, 0},
{"1 1", 1, func(i int) bool { return i >= 1 }, 1},
{"1 true", 1, func(i int) bool { return true }, 0},
{"1 false", 1, func(i int) bool { return false }, 1},
{"1e9 991", 1e9, func(i int) bool { return i >= 991 }, 991},
{"1e9 true", 1e9, func(i int) bool { return true }, 0},
{"1e9 false", 1e9, func(i int) bool { return false }, 1e9},
{"data -20", len(data), f(data, -20), 0},
{"data -10", len(data), f(data, -10), 0},
{"data -9", len(data), f(data, -9), 1},
{"data -6", len(data), f(data, -6), 1},
{"data -5", len(data), f(data, -5), 1},
{"data 3", len(data), f(data, 3), 5},
{"data 11", len(data), f(data, 11), 8},
{"data 99", len(data), f(data, 99), 9},
{"data 100", len(data), f(data, 100), 9},
{"data 101", len(data), f(data, 101), 12},
{"data 10000", len(data), f(data, 10000), 13},
{"data 10001", len(data), f(data, 10001), 14},
{"descending a", 7, func(i int) bool { return []int{99, 99, 59, 42, 7, 0, -1, -1}[i] <= 7 }, 4},
{"descending 7", 1e9, func(i int) bool { return 1e9-i <= 7 }, 1e9 - 7},
{"overflow", 2e9, func(i int) bool { return false }, 2e9},
}
func TestSearch(t *testing.T) {
for _, e := range tests {
i := Search(e.n, e.f)
if i != e.i {
t.Errorf("%s: expected index %d; got %d", e.name, e.i, i)
}
}
}
// log2 computes the binary logarithm of x, rounded up to the next integer.
// (log2(0) == 0, log2(1) == 0, log2(2) == 1, log2(3) == 2, etc.)
//
func log2(x int) int {
n := 0
for p := 1; p < x; p += p {
// p == 2**n
n++
}
// p/2 < x <= p == 2**n
return n
}
func TestSearchEfficiency(t *testing.T) {
n := 100
step := 1
for exp := 2; exp < 10; exp++ {
// n == 10**exp
// step == 10**(exp-2)
max := log2(n)
for x := 0; x < n; x += step {
count := 0
i := Search(n, func(i int) bool { count++; return i >= x })
if i != x {
t.Errorf("n = %d: expected index %d; got %d", n, x, i)
}
if count > max {
t.Errorf("n = %d, x = %d: expected <= %d calls; got %d", n, x, max, count)
}
}
n *= 10
step *= 10
}
}
// Smoke tests for convenience wrappers - not comprehensive.
var fdata = []float64{0: -3.14, 1: 0, 2: 1, 3: 2, 4: 1000.7}
var sdata = []string{0: "f", 1: "foo", 2: "foobar", 3: "x"}
var wrappertests = []struct {
name string
result int
i int
}{
{"SearchInts", SearchInts(data, 11), 8},
{"SearchFloat64s", SearchFloat64s(fdata, 2.1), 4},
{"SearchStrings", SearchStrings(sdata, ""), 0},
{"IntSlice.Search", IntSlice(data).Search(0), 2},
{"Float64Slice.Search", Float64Slice(fdata).Search(2.0), 3},
{"StringSlice.Search", StringSlice(sdata).Search("x"), 3},
}
func TestSearchWrappers(t *testing.T) {
for _, e := range wrappertests {
if e.result != e.i {
t.Errorf("%s: expected index %d; got %d", e.name, e.i, e.result)
}
}
}
func runSearchWrappers() {
SearchInts(data, 11)
SearchFloat64s(fdata, 2.1)
SearchStrings(sdata, "")
IntSlice(data).Search(0)
Float64Slice(fdata).Search(2.0)
StringSlice(sdata).Search("x")
}
func TestSearchWrappersDontAlloc(t *testing.T) {
if testing.Short() {
t.Skip("skipping malloc count in short mode")
}
if runtime.GOMAXPROCS(0) > 1 {
t.Skip("skipping; GOMAXPROCS>1")
}
allocs := testing.AllocsPerRun(100, runSearchWrappers)
if allocs != 0 {
t.Errorf("expected no allocs for runSearchWrappers, got %v", allocs)
}
}
func BenchmarkSearchWrappers(b *testing.B) {
for i := 0; i < b.N; i++ {
runSearchWrappers()
}
}
// Abstract exhaustive test: all sizes up to 100,
// all possible return values. If there are any small
// corner cases, this test exercises them.
func TestSearchExhaustive(t *testing.T) {
for size := 0; size <= 100; size++ {
for targ := 0; targ <= size; targ++ {
i := Search(size, func(i int) bool { return i >= targ })
if i != targ {
t.Errorf("Search(%d, %d) = %d", size, targ, i)
}
}
}
}
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