Make testing simple (#20)

* Make testing simpler

* Remove testing deps

* Simplemize tests

go.mod

@@ -1,5 +1,3 @@
 module github.com/sony/sonyflake
 
-go 1.12
-
-require github.com/deckarep/golang-set v1.7.1
+go 1.13

go.sum

@@ -1,2 +0,0 @@
-github.com/deckarep/golang-set v1.7.1 h1:SCQV0S6gTtp6itiFrTqI+pfmJ4LN85S1YzhDf9rTHJQ=
-github.com/deckarep/golang-set v1.7.1/go.mod h1:93vsz/8Wt4joVM7c2AVqh+YRMiUSc14yDtF28KmMOgQ=

sonyflake_test.go

@@ -5,8 +5,6 @@ import (
 	"runtime"
 	"testing"
 	"time"
-
-	"github.com/deckarep/golang-set"
 )
 
 var sf *Sonyflake
@@ -139,16 +137,15 @@ func TestSonyflakeInParallel(t *testing.T) {
 		go generate()
 	}
 
-	set := mapset.NewSet()
+	set := make(map[uint64]struct{})
 	for i := 0; i < numID*numGenerator; i++ {
 		id := <-consumer
-		if set.Contains(id) {
+		if _, ok := set[id]; ok {
 			t.Fatal("duplicated id")
-		} else {
-			set.Add(id)
 		}
+		set[id] = struct{}{}
 	}
-	fmt.Println("number of id:", set.Cardinality())
+	fmt.Println("number of id:", len(set))
 }
 
 func TestNilSonyflake(t *testing.T) {