add name generator

names-generator/names-generator.go

@@ -0,0 +1,30 @@
+package namesgenerator
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+type NameChecker interface {
+	Exists(name string) bool
+}
+
+var (
+	colors  = [...]string{"white", "silver", "gray", "black", "blue", "green", "cyan", "yellow", "gold", "orange", "brown", "red", "violet", "pink", "magenta", "purple"}
+	animals = [...]string{"ant", "bird", "cat", "chicken", "cow", "dog", "fish", "fox", "horse", "lion", "monkey", "pig", "sheep", "tiger", "whale", "wolf"}
+)
+
+func GenerateRandomName(checker NameChecker) (string, error) {
+	retry := 5
+	rand.Seed(time.Now().UnixNano())
+	name := fmt.Sprintf("%s_%s", colors[rand.Intn(len(colors))], animals[rand.Intn(len(animals))])
+	for checker != nil && checker.Exists(name) && retry > 0 {
+		name = fmt.Sprintf("%s%d", name, rand.Intn(10))
+		retry = retry - 1
+	}
+	if retry == 0 {
+		return name, fmt.Errorf("Error generating random name")
+	}
+	return name, nil
+}

names-generator/names-generator_test.go

@@ -0,0 +1,28 @@
+package namesgenerator
+
+import (
+	"testing"
+)
+
+type FalseChecker struct{}
+
+func (n *FalseChecker) Exists(name string) bool {
+	return false
+}
+
+type TrueChecker struct{}
+
+func (n *TrueChecker) Exists(name string) bool {
+	return true
+}
+
+func TestGenerateRandomName(t *testing.T) {
+	if _, err := GenerateRandomName(&FalseChecker{}); err != nil {
+		t.Error(err)
+	}
+
+	if _, err := GenerateRandomName(&TrueChecker{}); err == nil {
+		t.Error("An error was expected")
+	}
+
+}