From 43e44bc35b18c7e6938d8b5103ae8a76dd06f5a0 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@gmail.com>
Date: Tue, 22 Sep 2026 16:27:21 +0200
Subject: lib/routers: introduce router concept

---
 ttwhy/routers/echo.tests.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'ttwhy/routers/echo.tests.cpp')

diff --git a/ttwhy/routers/echo.tests.cpp b/ttwhy/routers/echo.tests.cpp
index f12d08b..c6ea10a 100644
--- a/ttwhy/routers/echo.tests.cpp
+++ b/ttwhy/routers/echo.tests.cpp
@@ -45,8 +45,32 @@ namespace
           token, buffers);
     }
   };
+
+  struct incomplete_router_no_policy
+  {
+    auto process(ttwhy::scanners::input_event) -> asio::awaitable<void>;
+  };
+
+  struct incomplete_router_no_process
+  {
+    using terminal_policy = ttwhy::scanners::xterm_policy;
+  };
+
+  struct incomplete_router_wrong_return
+  {
+    using terminal_policy = ttwhy::scanners::xterm_policy;
+    auto process(ttwhy::scanners::input_event) -> void;
+  };
 }  // namespace
 
+TEST_CASE("The router concept validates router candidate interfaces", "[router][concept]")
+{
+  STATIC_REQUIRE(ttwhy::router<ttwhy::routers::echo<mock_stream>>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_no_policy>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_no_process>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_wrong_return>);
+}
+
 SCENARIO("The echo router handles terminal navigation within the valid printed area", "[router][echo]")
 {
   GIVEN("An initialized echo router with a mock stream")
-- 
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