src/lib/sort_test.go

// Copyright 2009 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

import (
	"fmt";
	"rand";
	"sort";
	"testing";
)

func BentleyMcIlroyTests();


var ints = []int{74, 59, 238, -784, 9845, 959, 905, 0, 0, 42, 7586, -5467984, 7586}
var floats = []float{74.3, 59.0, 238.2, -784.0, 2.3, 9845.768, -959.7485, 905, 7.8, 7.8}
var strings = []string{"", "Hello", "foo", "bar", "foo", "f00", "%*&^*&^&", "***"}

export func TestSortIntArray(t *testing.T) {
	data := ints;
	a := sort.IntArray{data};
	sort.Sort(&a);
	if !sort.IsSorted(&a) {
		t.Errorf("sorted %v", ints);
		t.Errorf("   got %v", data);
	}
}

export func TestSortFloatArray(t *testing.T) {
	data := floats;
	a := sort.FloatArray{data};
	sort.Sort(&a);
	if !sort.IsSorted(&a) {
		t.Errorf("sorted %v", floats);
		t.Errorf("   got %v", data);
	}
}

export func TestSortStringArray(t *testing.T) {
	data := strings;
	a := sort.StringArray{data};
	sort.Sort(&a);
	if !sort.IsSorted(&a) {
		t.Errorf("sorted %v", strings);
		t.Errorf("   got %v", data);
	}
}

export func TestSortInts(t *testing.T) {
	data := ints;
	sort.SortInts(data);
	if !sort.IntsAreSorted(data) {
		t.Errorf("sorted %v", ints);
		t.Errorf("   got %v", data);
	}
}

export func TestSortFloats(t *testing.T) {
	data := floats;
	sort.SortFloats(data);
	if !sort.FloatsAreSorted(data) {
		t.Errorf("sorted %v", floats);
		t.Errorf("   got %v", data);
	}
}

export func TestSortStrings(t *testing.T) {
	data := strings;
	sort.SortStrings(data);
	if !sort.StringsAreSorted(data) {
		t.Errorf("sorted %v", strings);
		t.Errorf("   got %v", data);
	}
}

export func TestSortLargeRandom(t *testing.T) {
	data := make([]int, 1000000);
	for i := 0; i < len(data); i++ {
		data[i] = rand.rand() % 100;
	}
	if sort.IntsAreSorted(data) {
		t.Fatalf("terrible rand.rand");
	}
	sort.SortInts(data);
	if !sort.IntsAreSorted(data) {
		t.Errorf("sort didn't sort - 1M ints");
	}
}

const (
	Sawtooth = iota;
	Rand;
	Stagger;
	Plateau;
	Shuffle;
	NDist;
)

const (
	Copy = iota;
	Reverse;
	ReverseFirstHalf;
	ReverseSecondHalf;
	Sorted;
	Dither;
	NMode;
);

type TestingData struct {
	desc string;
	t *testing.T;
	data []int;
	maxswap int;	// number of swaps allowed
	nswap int;
}

func (d *TestingData) Len() int { return len(d.data); }
func (d *TestingData) Less(i, j int) bool { return d.data[i] < d.data[j]; }
func (d *TestingData) Swap(i, j int) {
	if d.nswap >= d.maxswap {
		d.t.Errorf("%s: used %d swaps sorting array of %d", d.desc, d.nswap, len(d.data));
		d.t.FailNow();
	}
	d.nswap++;
	d.data[i], d.data[j] = d.data[j], d.data[i];
}

func Lg(n int) int {
	i := 0;
	for 1<<uint(i) < n {
		i++;
	}
	return i;
}

func Min(a, b int) int {
	if a < b {
		return a;
	}
	return b;
}

export func TestBentleyMcIlroy(t *testing.T) {
	sizes := []int{100, 1023, 1024, 1025};
	dists := []string{"sawtooth", "rand", "stagger", "plateau", "shuffle"};
	modes := []string{"copy", "reverse", "reverse1", "reverse2", "sort", "dither"};
	var tmp1, tmp2 [1025]int;
	for ni := 0; ni < len(sizes); ni++ {
		n := sizes[ni];
		for m := 1; m < 2*n; m *= 2 {
			for dist := 0; dist < NDist; dist++ {
				j := 0;
				k := 1;
				data := tmp1[0:n];
				for i := 0; i < n; i++ {
					switch dist {
					case Sawtooth:
						data[i] = i % m;
					case Rand:
						data[i] = rand.rand() % m;
					case Stagger:
						data[i] = (i*m + i) % n;
					case Plateau:
						data[i] = Min(i, m);
					case Shuffle:
						if rand.rand() % m != 0 {
							j += 2;
							data[i] = j;
						} else {
							k += 2;
							data[i] = k;
						}
					}
				}

				mdata := tmp2[0:n];
				for mode := 0; mode < NMode; mode++ {
					switch mode {
					case Copy:
						for i := 0; i < n; i++ {
							mdata[i] = data[i];
						}
					case Reverse:
						for i := 0; i < n; i++ {
							mdata[i] = data[n-i-1];
						}
					case ReverseFirstHalf:
						for i := 0; i < n/2; i++ {
							mdata[i] = data[n/2-i-1];
						}
						for i := n/2; i < n; i++ {
							mdata[i] = data[i];
						}
					case ReverseSecondHalf:
						for i := 0; i < n/2; i++ {
							mdata[i] = data[i];
						}
						for i := n/2; i < n; i++ {
							mdata[i] = data[n-(i-n/2)-1];
						}
					case Sorted:
						for i := 0; i < n; i++ {
							mdata[i] = data[i];
						}
						// sort.SortInts is known to be correct
						// because mode Sort runs after mode Copy.
						sort.SortInts(mdata);
					case Dither:
						for i := 0; i < n; i++ {
							mdata[i] = data[i] + i%5;
						}
					}

					desc := fmt.sprintf("n=%d m=%d dist=%s mode=%s", n, m, dists[dist], modes[mode]);
					d := &TestingData{desc, t, mdata[0:n], n*Lg(n)*12/10, 0};
					sort.Sort(d);

					// If we were testing C qsort, we'd have to make a copy
					// of the array and sort it ourselves and then compare
					// x against it, to ensure that qsort was only permuting
					// the data, not (for example) overwriting it with zeros.
					//
					// In go, we don't have to be so paranoid: since the only
					// mutating method sort.Sort can call is TestingData.swap,
					// it suffices here just to check that the final array is sorted.
					if !sort.IntsAreSorted(mdata) {
						t.Errorf("%s: ints not sorted", desc);
						t.Errorf("\t%v", mdata);
						t.FailNow();
					}
				}
			}
		}
	}
}