add: random element and weighted random element. (#170)

* add: random element and weighted random element.

* fix: time format in ISO8601.

faker_test.go

@@ -556,6 +556,13 @@ func TestMap(t *testing.T) {
 	Expect(t, true, len(mp) > 0)
 }
 
+func TestRandomStringElement(t *testing.T) {
+	f := New()
+	m := []string{"str1", "str2"}
+	randomStr := f.RandomStringElement(m)
+	Expect(t, true, randomStr == "str1" || randomStr == "str2")
+}
+
 func TestRandomStringMapKey(t *testing.T) {
 	f := New()
 	m := map[string]string{"k0": "v0", "k1": "v1"}

random_element.go

@@ -0,0 +1,26 @@
+package faker
+
+// RandomElement returns a fake random element from a given list of elements
+func RandomElement[T any](f Faker, elements ...T) T {
+	i := f.IntBetween(0, len(elements)-1)
+	return elements[i]
+}
+
+// RandomElementWeighted takes faker instance and a list of elements in the form of map[weight]element,
+// it then selects one of the elements randomly and returns it,
+//
+// Elements with higher weight have more chance to be returned.
+func RandomElementWeighted[T any](f Faker, elements map[int]T) T {
+	arrayOfElements := make([]T, 0)
+
+	for weight, value := range elements {
+		// TODO: there is an accepted proposal for generic slices.Repeat function in Go 1.23
+		for i := 0; i < weight; i++ {
+			arrayOfElements = append(arrayOfElements, value)
+		}
+	}
+
+	i := f.IntBetween(0, len(arrayOfElements)-1)
+
+	return arrayOfElements[i]
+}

random_element_test.go

@@ -0,0 +1,25 @@
+package faker
+
+import "testing"
+
+func TestRandomElement(t *testing.T) {
+	f := New()
+	m := []string{"str1", "str2"}
+	randomStr := RandomElement(f, m...)
+	Expect(t, true, randomStr == "str1" || randomStr == "str2")
+}
+
+func TestRandomElementWeighted(t *testing.T) {
+	f := New()
+	m := map[int]string{
+		0: "zeroChance",
+		1: "someChance",
+		5: "moreChance",
+	}
+
+	for i := 0; i < 5; i++ {
+		got := RandomElementWeighted(f, m)
+		Expect(t, true, got == "someChance" || got == "moreChance")
+		Expect(t, true, got != "zeroChance")
+	}
+}

time.go

@@ -33,7 +33,7 @@ func (t Time) TimeBetween(min, max time.Time) time.Time {
 // ISO8601 returns a fake time in ISO8601 format for Time
 func (t Time) ISO8601(max time.Time) string {
 	t1 := t.Time(max)
-	return t1.Format("2006-02-01T15:04:05+000")
+	return t1.Format("2006-01-02T15:04:05+000")
 }
 
 // ANSIC returns a fake time in ANSIC format for Time