feat: add RandUniqueIntSlice (#108)

random/random.go

@@ -114,3 +114,27 @@ func UUIdV4() (string, error) {
 
 	return fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:]), nil
 }
+
+// RandUniqueIntSlice generate a slice of random int of length n that do not repeat
+func RandUniqueIntSlice(n, min, max int) []int {
+	if min > max {
+		return []int{}
+	}
+	if n > max-min {
+		n = max - min
+	}
+
+	nums := make([]int, n)
+	used := make(map[int]struct{}, n)
+	for i := 0; i < n; {
+		r := RandInt(min, max)
+		if _, use := used[r]; use {
+			continue
+		}
+		used[r] = struct{}{}
+		nums[i] = r
+		i++
+	}
+
+	return nums
+}

random/random_example_test.go

@@ -123,3 +123,14 @@ func ExampleUUIdV4() {
 	// Output:
 	// true
 }
+
+func ExampleRandUniqueIntSlice() {
+	result := RandUniqueIntSlice(5, 0, 10)
+
+	if len(result) == 5 {
+		fmt.Println("ok")
+	}
+
+	// Output:
+	// ok
+}

random/random_test.go

@@ -103,3 +103,36 @@ func TestUUIdV4(t *testing.T) {
 	isUUiDV4 := regexp.MustCompile(`^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$`)
 	assert.Equal(true, isUUiDV4.MatchString(uuid))
 }
+
+func TestRandUniqueIntSlice(t *testing.T) {
+	assert := internal.NewAssert(t, "TestRandUniqueIntSlice")
+
+	r1 := RandUniqueIntSlice(5, 0, 9)
+	assert.Equal(len(r1), 5)
+	if hasDuplicate(r1) {
+		t.Error("hasDuplicate int")
+	}
+
+	r2 := RandUniqueIntSlice(20, 0, 10)
+	assert.Equal(len(r2), 10)
+	if hasDuplicate(r2) {
+		t.Error("hasDuplicate int")
+	}
+
+	r3 := RandUniqueIntSlice(10, 20, 10)
+	assert.Equal(len(r3), 0)
+
+	r4 := RandUniqueIntSlice(0, 20, 10)
+	assert.Equal(len(r4), 0)
+}
+
+func hasDuplicate(arr []int) bool {
+	elements := make(map[int]bool)
+	for _, v := range arr {
+		if elements[v] {
+			return true
+		}
+		elements[v] = true
+	}
+	return false
+}