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// Copyright 2025 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package intset
import (
"fmt"
"math/bits"
"math/rand/v2"
"testing"
"time"
)
// populate fills the set with n sequential values (0..n-1) and verifies
// insertion invariants along the way.
func populate[T Int](t *testing.T, n int) *Set[T] {
t.Helper()
s := New[T](n / 2) // intentionally small to exercise growth
for i := 0; i < n; i++ {
if !s.Add(T(i)) {
t.Fatalf("insert %d reported duplicate", i)
}
}
if got := s.Len(); got != n {
t.Fatalf("Len=%d, want %d", got, n)
}
return s
}
// assertPresent asserts that Has(v) equals want for every v in vals.
func assertPresent[T Int](t *testing.T, s *Set[T], vals []T, want bool) {
t.Helper()
for _, v := range vals {
if got := s.Has(v); got != want {
t.Fatalf("Has(%v)=%v, want %v", v, got, want)
}
}
}
func TestBasicAddHasLen(t *testing.T) {
s := New[uint32](8)
if s.Len() != 0 {
t.Fatalf("new set length want 0 got %d", s.Len())
}
if !s.Add(10) {
t.Fatalf("expected first insertion true")
}
if s.Len() != 1 || !s.Has(10) {
t.Fatalf("basic invariants failed")
}
if s.Add(10) {
t.Fatalf("duplicate insertion should return false")
}
if s.Len() != 1 {
t.Fatalf("duplicate insertion changed size")
}
}
func TestClear(t *testing.T) {
s := populate[uint16](t, 50)
s.Clear()
if s.Len() != 0 {
t.Fatalf("Len after Clear() = %d, want 0", s.Len())
}
assertPresent(t, s, []uint16{0, 25, 49}, false)
// ensure we can reuse without reallocation or corruption
for i := 0; i < 20; i++ {
s.Add(uint16(i))
}
if s.Len() != 20 {
t.Fatalf("Len after reuse = %d, want 20", s.Len())
}
}
func TestRehashGrowth(t *testing.T) {
// create a small set to guarantee multiple growth events
initialCap := 8
s := New[uint32](initialCap)
target := 10_000
for i := 0; i < target; i++ {
s.Add(uint32(i))
}
if s.Len() != target {
t.Fatalf("after bulk add Len=%d want %d", s.Len(), target)
}
// verify every element is present
for i := 0; i < target; i++ {
if !s.Has(uint32(i)) {
t.Fatalf("missing key %d after growth", i)
}
}
// internal capacity should be power-of-two
if bits.OnesCount(uint(len(s.keys))) != 1 {
t.Fatalf("internal slice len=%d, not power-of-two", len(s.keys))
}
}
func TestMultipleIntegerSizes(t *testing.T) {
t.Run("uint8", func(t *testing.T) { populate[uint8](t, 200) })
t.Run("uint16", func(t *testing.T) { populate[uint16](t, 1_000) })
t.Run("uint32", func(t *testing.T) { populate[uint32](t, 10_000) })
t.Run("uint64", func(t *testing.T) { populate[uint64](t, 1_000) })
}
func TestNextPow2(t *testing.T) {
tests := []struct{ in, want int }{{0, 1}, {1, 1}, {2, 2}, {3, 4}, {7, 8}, {8, 8}, {9, 16}, {1023, 1024}, {1024, 1024}, {1025, 2048}}
for _, test := range tests {
t.Run(fmt.Sprint(test.in), func(t *testing.T) {
if got := nextPow2(test.in); got != test.want {
t.Fatalf("nextPow2(%d)=%d, want %d", test.in, got, test.want)
}
})
}
}
// TestRandomizedBehaviour performs a behavioural, property-style test on a
// large batch of pseudo-random keys. It uses an auxiliary Go map to model the
// expected behaviour and cross-checks all edge cases, exercising rehash logic
// many times along the way.
func TestRandomizedBehaviour(t *testing.T) {
const N = 100_000
seed := uint64(time.Now().UnixNano())
t.Logf("random seed %d", seed)
randGen := rand.New(rand.NewPCG(seed, seed))
s := New[uint32](8) // deliberately tiny to trigger dozens of rehashes
model := make(map[uint32]struct{})
for i := 0; i < N; i++ {
k := randGen.Uint32()
added := s.Add(k)
_, exists := model[k]
if added == exists {
t.Fatalf("Add(%d) reported %v, expected %v (iteration %d)", k, added, !exists, i)
}
model[k] = struct{}{}
if !s.Has(k) {
t.Fatalf("Has(%d)=false immediately after add", k)
}
if s.Len() != len(model) {
t.Fatalf("Len mismatch at i=%d: set=%d, model=%d", i, s.Len(), len(model))
}
}
for k := range model {
if !s.Has(k) {
t.Fatalf("Has(%d)=false at end, should be true", k)
}
}
// sanity check on internal capacity: should be power of two and at least len/model * 4/3 (load factor)
if bits.OnesCount(uint(len(s.keys))) != 1 {
t.Fatalf("internal slice len=%d, not power of two", len(s.keys))
}
}
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