priorityq/binheap/lib_test.go

package binheap_test

import (
	"math/rand"
	"testing"

	"gogs.humancabbage.net/sam/priorityq/binheap"
)

func TestSmoke(t *testing.T) {
	h := binheap.Make[int, int](10)
	if h.Capacity() != 10 {
		t.Errorf("expected heap capacity to be 10")
	}
	h.Insert(1, 1)
	h.Insert(2, 2)
	h.Insert(3, 3)
	h.Insert(4, 4)
	if h.Len() != 4 {
		t.Errorf("expected heap length to be 4")
	}
	checkExtract := func(n int) {
		_, extracted := h.Extract()
		if extracted != n {
			t.Errorf("expected to extract %d, got %d", n, extracted)
		}
	}
	checkExtract(4)
	checkExtract(3)
	checkExtract(2)
	checkExtract(1)
}

func TestInsertFullPanic(t *testing.T) {
	h := binheap.Make[int, int](4)
	h.Insert(1, 1)
	h.Insert(2, 2)
	h.Insert(3, 3)
	h.Insert(4, 4)
	defer func() {
		if r := recover(); r == nil {
			t.Errorf("expected final insert to panic")
		}
	}()
	h.Insert(5, 5)
}

func TestExtractEmptyPanic(t *testing.T) {
	h := binheap.Make[int, int](4)
	defer func() {
		if r := recover(); r == nil {
			t.Errorf("expected extract to panic")
		}
	}()
	h.Extract()
}

func TestRandomized(t *testing.T) {
	h := binheap.Make[int, int](8192)
	rs := rand.NewSource(0)
	r := rand.New(rs)
	// insert a bunch of random integers
	for i := 0; i < h.Capacity(); i++ {
		n := r.Int()
		h.Insert(n, n)
	}
	// ensure that each extracted integer is <= the last extracted integer
	var extracted []int
	for h.CanExtract() {
		id, item := h.Extract()
		if id != item {
			t.Errorf("id / item mismatch: %d %d", id, item)
		}
		lastIdx := len(extracted) - 1
		extracted = append(extracted, item)
		if lastIdx < 0 {
			continue
		}
		if item > extracted[lastIdx] {
			t.Errorf("newly extracted %d is greater than %d",
				item, extracted[lastIdx])
		}
	}
}

func BenchmarkInsert(b *testing.B) {
	h := binheap.Make[int, int](b.N)
	rs := rand.NewSource(0)
	r := rand.New(rs)
	items := make([]int, b.N)
	for i := 0; i < b.N; i++ {
		items[i] = r.Int()
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		h.Insert(items[i], items[i])
	}
}

func BenchmarkExtract(b *testing.B) {
	h := binheap.Make[int, int](b.N)
	rs := rand.NewSource(0)
	r := rand.New(rs)
	for i := 0; i < b.N; i++ {
		n := r.Int()
		h.Insert(n, n)
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		h.Extract()
	}
}

func BenchmarkRepeatedInsertExtract(b *testing.B) {
	h := binheap.Make[int, int](128)
	rs := rand.NewSource(0)
	r := rand.New(rs)
	items := make([]int, b.N)
	for i := 0; i < h.Capacity()-1; i++ {
		n := r.Int()
		h.Insert(n, n)
	}
	for i := 0; i < b.N; i++ {
		items[i] = r.Int()
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		h.Insert(items[i], items[i])
		h.Extract()
	}
}