From 1855a86d0409069e25c3c87725d5e0eb1bf556eb Mon Sep 17 00:00:00 2001
From: armanmikoyan <arman.mikoyan1@gmail.com>
Date: Mon, 27 Jul 2026 14:19:52 +0400
Subject: [PATCH] feat: add app-aware router creation

---
 lib/application.js       | 17 +++++++++++++++++
 test/app.createRouter.js | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 test/app.createRouter.js

diff --git a/lib/application.js b/lib/application.js
index 310e6dfef21..09c1718adac 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -605,6 +605,23 @@ app.listen = function listen() {
   return server.listen.apply(server, args)
 }
 
+/**
+ * Create a router that inherits this application's routing settings.
+ *
+ * @param {Object} [options]
+ * @return {Router}
+ * @public
+ */
+
+app.createRouter = function createRouter(options) {
+  options = Object.assign({
+    caseSensitive: this.enabled('case sensitive routing'),
+    strict: this.enabled('strict routing')
+  }, options)
+
+  return new Router(options)
+}
+
 /**
  * Log error using console.error.
  *
diff --git a/test/app.createRouter.js b/test/app.createRouter.js
new file mode 100644
index 00000000000..c754206f295
--- /dev/null
+++ b/test/app.createRouter.js
@@ -0,0 +1,40 @@
+'use strict'
+
+var assert = require('node:assert')
+var express = require('../')
+
+describe('app.createRouter()', function () {
+  it('should inherit routing settings from the app', function () {
+    var app = express()
+
+    app.enable('case sensitive routing')
+    app.enable('strict routing')
+
+    var router = app.createRouter()
+
+    assert.strictEqual(router.caseSensitive, true)
+    assert.strictEqual(router.strict, true)
+  })
+
+  it('should allow options to override inherited settings', function () {
+    var app = express()
+
+    app.enable('case sensitive routing')
+    app.enable('strict routing')
+
+    var router = app.createRouter({
+      caseSensitive: false,
+      strict: false
+    })
+
+    assert.strictEqual(router.caseSensitive, false)
+    assert.strictEqual(router.strict, false)
+  })
+
+  it('should pass other options to the router', function () {
+    var app = express()
+    var router = app.createRouter({ mergeParams: true })
+
+    assert.strictEqual(router.mergeParams, true)
+  })
+})