add test case16 for copy rete limiter

all_test.go

@@ -3,10 +3,12 @@ package copy
 import (
 	"errors"
 	"io/ioutil"
+	"math"
 	"os"
 	"runtime"
 	"strings"
 	"testing"
+	"time"
 
 	. "github.com/otiai10/mint"
 )
@@ -326,3 +328,28 @@ func TestOptions_PreserveOwner(t *testing.T) {
 	err := Copy("test/data/case13", "test/data.copy/case13", opt)
 	Expect(t, err).ToBe(nil)
 }
+
+func TestOptions_CopyRateLimit(t *testing.T) {
+	opt := Options{CopyRateLimit: 50} // 50 KB/s
+	size := int64(100 * 1024)         // 100 KB
+	costSec := int64(2)               // 2 seconds
+
+	file, err := os.Create("test/data/case16/large.file")
+	if err != nil {
+		t.Errorf("failed to create test file: %v", err)
+		return
+	}
+
+	if err := file.Truncate(size); err != nil {
+		t.Errorf("failed to truncate test file: %v", err)
+		t.SkipNow()
+		return
+	}
+
+	start := time.Now()
+	err = Copy("test/data/case16", "test/data.copy/case16", opt)
+	copyCost := time.Since(start)
+	Expect(t, err).ToBe(nil)
+	t.Log("copy cost", copyCost)
+	Expect(t, int64(math.Floor(copyCost.Seconds()+0.5)) == costSec).ToBe(true)
+}

ratelimited_reader.go

@@ -12,7 +12,7 @@ type RateLimitedReader struct {
 }
 
 // NewRateLimitedReader
-// n means the number of Kb to be read per second
+// n means the number of KB to be read per second
 func NewRateLimitedReader(src io.Reader, n int64) io.Reader {
 	return &RateLimitedReader{
 		src:     src,

test/data/case16/README.md

@@ -0,0 +1,5 @@
+So if you wanted to limit copy rate with a KB/second value, you could add options like this:
+```go
+opt.CopyRateLimit = 100
+```
+The default value is 0, which means no limit.