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|
package mem
import (
"fmt"
"testing"
)
var (
countPairSizes = [...]int{
1, 2, 4, 8, 10, 16, 32,
}
)
func TestCountPair(t *testing.T) {
for _, size := range countPairSizes {
makeInput := func(values ...byte) []byte {
input := make([]byte, size*len(values))
for i := range values {
input[i*size] = values[i]
}
return input
}
t.Run(fmt.Sprintf("N=%d", size), func(t *testing.T) {
tests := []struct {
scenario string
input []byte
count int
}{
{
scenario: "empty input",
input: nil,
count: 0,
},
{
scenario: "input with only one item",
input: makeInput(1),
count: 0,
},
{
scenario: "input with two non-equal items",
input: makeInput(1, 2),
count: 0,
},
{
scenario: "input with two equal items",
input: makeInput(1, 1),
count: 1,
},
{
scenario: "input with two equal items in the middle",
input: makeInput(0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9),
count: 1,
},
{
scenario: "input with two equal items at the end",
input: makeInput(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9),
count: 1,
},
{
scenario: "input with many equal items at the beginning of a long sequence",
input: makeInput(
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
),
count: 9,
},
{
scenario: "input with many equal items in the middle of a long sequence",
input: makeInput(
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
0, 1, 2, 3, 4, 5, 6, 7, 8,
),
count: 9,
},
{
scenario: "input with many equal items in a long sequence",
input: makeInput(
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
0, 1, 2, 3, 4, 5, 6, 7, 0,
),
count: 15,
},
}
for _, test := range tests {
t.Run(test.scenario, func(t *testing.T) {
n := CountPair(test.input, size)
if n != test.count {
t.Errorf("expected=%d found=%d", test.count, n)
}
})
}
})
}
}
func BenchmarkCountPair(b *testing.B) {
for _, size := range countPairSizes {
input := make([]byte, 16*1024)
for i := range input {
input[i] = byte(i)
}
if size%len(input) != 0 {
input = input[:(len(input)/size)*size]
}
b.Run(fmt.Sprintf("N=%d", size), func(b *testing.B) {
b.SetBytes(int64(len(input)))
for i := 0; i < b.N; i++ {
n := CountPair(input, size)
if n != 0 {
b.Fatal("unexpected result:", n)
}
}
})
}
}
|
