internal/validate: relocate from app

These are free of the dispatcher from internal/app. This change relocates them into their own package.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/validate/username_test.go

@@ -0,0 +1,30 @@
+package validate_test
+
+import (
+	"strings"
+	"testing"
+
+	"hakurei.app/internal/validate"
+)
+
+func TestIsValidUsername(t *testing.T) {
+	t.Parallel()
+
+	t.Run("long", func(t *testing.T) {
+		if validate.IsValidUsername(strings.Repeat("a", validate.Sysconf(validate.SC_LOGIN_NAME_MAX))) {
+			t.Errorf("IsValidUsername unexpected true")
+		}
+	})
+
+	t.Run("regexp", func(t *testing.T) {
+		if validate.IsValidUsername("0") {
+			t.Errorf("IsValidUsername unexpected true")
+		}
+	})
+
+	t.Run("valid", func(t *testing.T) {
+		if !validate.IsValidUsername("alice") {
+			t.Errorf("IsValidUsername unexpected false")
+		}
+	})
+}