Add handle pkg

pkg/handle/handle.go

@@ -0,0 +1,13 @@
+package handle
+
+import (
+	"regexp"
+)
+
+var (
+	c = regexp.MustCompile(`^[A-Za-z][0-9A-Za-z_\-.]*[A-Za-z0-9]$`)
+)
+
+func IsValid(s string) bool {
+	return s == "" || (len(s) >= 2 && c.MatchString(s))
+}

pkg/handle/handle_test.go

@@ -0,0 +1,30 @@
+package handle
+
+import (
+	"testing"
+)
+
+func TestIsValid(t *testing.T) {
+	tests := []struct {
+		name   string
+		handle string
+		want   bool
+	}{
+		// TODO: Add test cases.
+		{"empty", "", true},
+		{"alphanum", "a1", true},
+		{"alpha", "abc", true},
+		{"num", "123", false},
+		{"valid1", "Valid1Handle", true},
+		{"valid2", "Valid-Handle", true},
+		{"valid3", "Valid_Handle", true},
+		{"weirdo", "a$&_.!", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IsValid(tt.handle); got != tt.want {
+				t.Errorf("IsValid() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}