ringbuffer_test.gno

  1package ringbuffer
  2
  3import (
  4	"strings"
  5	"testing"
  6
  7	"gno.land/p/nt/uassert/v0"
  8)
  9
 10func TestPushPopFIFO(t *testing.T) {
 11	r := New(3)
 12	r.Push("a")
 13	r.Push("b")
 14	uassert.Equal(t, 2, r.Len())
 15	v, ok := r.Pop()
 16	uassert.True(t, ok)
 17	uassert.Equal(t, "a", v)
 18	v, _ = r.Pop()
 19	uassert.Equal(t, "b", v)
 20	_, ok = r.Pop()
 21	uassert.False(t, ok)
 22}
 23
 24// The defining behaviour: full means overwrite the oldest, and say so.
 25func TestOverwriteOldest(t *testing.T) {
 26	r := New(3)
 27	for _, s := range []string{"a", "b", "c"} {
 28		ev, dropped := r.Push(s)
 29		uassert.False(t, dropped)
 30		uassert.Equal(t, "", ev)
 31	}
 32	uassert.True(t, r.Full())
 33	ev, dropped := r.Push("d")
 34	uassert.True(t, dropped)
 35	uassert.Equal(t, "a", ev) // the OLDEST went, not the newest
 36	uassert.Equal(t, "b,c,d", strings.Join(r.Slice(), ","))
 37	uassert.Equal(t, 3, r.Len())
 38}
 39
 40// Wrapping must not corrupt order — the classic ring-buffer bug.
 41func TestWrapAroundKeepsOrder(t *testing.T) {
 42	r := New(3)
 43	for _, s := range []string{"1", "2", "3", "4", "5", "6", "7"} {
 44		r.Push(s)
 45	}
 46	uassert.Equal(t, "5,6,7", strings.Join(r.Slice(), ","))
 47	v, _ := r.Peek()
 48	uassert.Equal(t, "5", v)
 49}
 50
 51// Interleaving Pop and Push moves head and tail independently.
 52func TestInterleavedPushPop(t *testing.T) {
 53	r := New(3)
 54	r.Push("a")
 55	r.Push("b")
 56	r.Pop() // drop a
 57	r.Push("c")
 58	r.Push("d") // fills: b,c,d
 59	uassert.Equal(t, "b,c,d", strings.Join(r.Slice(), ","))
 60	ev, dropped := r.Push("e")
 61	uassert.True(t, dropped)
 62	uassert.Equal(t, "b", ev)
 63	uassert.Equal(t, "c,d,e", strings.Join(r.Slice(), ","))
 64}
 65
 66func TestAt(t *testing.T) {
 67	r := New(3)
 68	r.Push("a")
 69	r.Push("b")
 70	v, ok := r.At(0)
 71	uassert.True(t, ok)
 72	uassert.Equal(t, "a", v) // 0 is the OLDEST
 73	v, _ = r.At(1)
 74	uassert.Equal(t, "b", v)
 75	_, ok = r.At(2)
 76	uassert.False(t, ok)
 77	_, ok = r.At(-1)
 78	uassert.False(t, ok)
 79}
 80
 81// A zero-capacity buffer stores nothing and admits it rather than pretending.
 82func TestZeroCapacity(t *testing.T) {
 83	r := New(0)
 84	uassert.Equal(t, 0, r.Cap())
 85	ev, dropped := r.Push("x")
 86	uassert.True(t, dropped)
 87	uassert.Equal(t, "x", ev)
 88	uassert.True(t, r.Empty())
 89	uassert.False(t, r.Full()) // a buffer that holds nothing is never "full"
 90	uassert.Equal(t, 0, len(r.Slice()))
 91}
 92
 93func TestEmptyPeekPop(t *testing.T) {
 94	r := New(2)
 95	_, ok := r.Peek()
 96	uassert.False(t, ok)
 97	_, ok = r.Pop()
 98	uassert.False(t, ok)
 99}
100
101func TestReset(t *testing.T) {
102	r := New(3)
103	r.Push("a")
104	r.Push("b")
105	r.Reset()
106	uassert.True(t, r.Empty())
107	uassert.Equal(t, 0, r.Len())
108	r.Push("z")
109	uassert.Equal(t, "z", strings.Join(r.Slice(), ","))
110}
111
112func TestSliceIsACopy(t *testing.T) {
113	r := New(3)
114	r.Push("a")
115	s := r.Slice()
116	s[0] = "mutated"
117	uassert.Equal(t, "a", strings.Join(r.Slice(), ","))
118}
119
120func TestCapClamped(t *testing.T) {
121	uassert.Equal(t, 0, New(-5).Cap())
122	uassert.Equal(t, MaxCap, New(MaxCap+100).Cap())
123}