1 files changed, 257 insertions, 0 deletions
diff --git a/ttwhy/terminal/echo.tests.cpp b/ttwhy/terminal/echo.tests.cpp
new file mode 100644
index 0000000..ba07d55
--- /dev/null
+++ b/ttwhy/terminal/echo.tests.cpp
@@ -0,0 +1,257 @@
+#include <asio.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <string>
+#include <string_view>
+#include <utility>
+
+import ttwhy.core;
+import ttwhy.terminal;
+
+using namespace std::string_view_literals;
+
+namespace
+{
+  struct mock_stream
+  {
+    using executor_type = asio::any_io_executor;
+
+    asio::any_io_executor executor;
+    std::string written{};
+
+    explicit mock_stream(asio::any_io_executor exec)
+        : executor{std::move(exec)}
+    {}
+
+    auto get_executor() const noexcept -> executor_type
+    {
+      return executor;
+    }
+
+    template<typename ConstBufferSequence, typename Token>
+    auto async_write_some(ConstBufferSequence const & buffers, Token && token)
+    {
+      return asio::async_initiate<Token, void(asio::error_code, std::size_t)>(
+          [this](auto handler, ConstBufferSequence bufs) {
+            auto const total = asio::buffer_size(bufs);
+            auto const offset = written.size();
+            written.resize(offset + total);
+            asio::buffer_copy(asio::buffer(written.data() + offset, total), bufs);
+            asio::post(executor, [handler = std::move(handler), total]() mutable {
+              std::move(handler)(asio::error_code{}, total);
+            });
+          },
+          token, buffers);
+    }
+  };
+
+  struct incomplete_router_no_process
+  {
+  };
+
+  struct incomplete_router_wrong_return
+  {
+    auto process(ttwhy::terminal::input_event) -> void;
+  };
+
+  struct incomplete_router_wrong_event
+  {
+    auto process(int) -> asio::awaitable<void>;
+  };
+}  // namespace
+
+TEST_CASE("The router concept validates router candidate interfaces", "[router][concept]")
+{
+  STATIC_REQUIRE(ttwhy::router<ttwhy::terminal::echo<mock_stream>, ttwhy::terminal::input_event>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_no_process, ttwhy::terminal::input_event>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_wrong_return, ttwhy::terminal::input_event>);
+  STATIC_REQUIRE_FALSE(ttwhy::router<incomplete_router_wrong_event, ttwhy::terminal::input_event>);
+}
+
+SCENARIO("The echo router handles terminal navigation within the valid printed area", "[router][echo]")
+{
+  GIVEN("An initialized echo router with a mock stream")
+  {
+    auto context = asio::io_context{};
+    auto stream = mock_stream{context.get_executor()};
+    auto router = ttwhy::terminal::echo{stream};
+
+    auto run_coro = [&](asio::awaitable<void> coro) {
+      asio::co_spawn(context, std::move(coro), asio::detached);
+      context.restart();
+      context.run();
+    };
+
+    WHEN("Typing characters")
+    {
+      run_coro(router.process(ttwhy::terminal::character_event{'A'}));
+      run_coro(router.process(ttwhy::terminal::character_event{'B'}));
+
+      THEN("Characters are echoed and positions advance")
+      {
+        CHECK(stream.written == "AB");
+        CHECK(router.cursor_position() == 2);
+        CHECK(router.max_position() == 2);
+      }
+
+      AND_WHEN("Navigating left")
+      {
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::left}));
+
+        THEN("The cursor moves left")
+        {
+          CHECK(stream.written == "\x1b[D");
+          CHECK(router.cursor_position() == 1);
+          CHECK(router.max_position() == 2);
+        }
+
+        AND_WHEN("Navigating left again to position 0")
+        {
+          stream.written.clear();
+          run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::left}));
+
+          THEN("The cursor reaches 0")
+          {
+            CHECK(stream.written == "\x1b[D");
+            CHECK(router.cursor_position() == 0);
+            CHECK(router.max_position() == 2);
+          }
+
+          AND_WHEN("Attempting to navigate left beyond 0")
+          {
+            stream.written.clear();
+            run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::left}));
+
+            THEN("Navigation is prevented and nothing is emitted")
+            {
+              CHECK(stream.written.empty());
+              CHECK(router.cursor_position() == 0);
+              CHECK(router.max_position() == 2);
+            }
+          }
+        }
+      }
+
+      AND_WHEN("Attempting to navigate right beyond what was printed")
+      {
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::right}));
+
+        THEN("Navigation is prevented and nothing is emitted")
+        {
+          CHECK(stream.written.empty());
+          CHECK(router.cursor_position() == 2);
+          CHECK(router.max_position() == 2);
+        }
+      }
+
+      AND_WHEN("Navigating left and then overwriting with new character")
+      {
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::left}));
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::character_event{'X'}));
+
+        THEN("The new character is written and max position is preserved")
+        {
+          CHECK(stream.written == "X");
+          CHECK(router.cursor_position() == 2);
+          CHECK(router.max_position() == 2);
+        }
+      }
+
+      AND_WHEN("Using Home and End keys")
+      {
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::home}));
+
+        THEN("Home navigates to 0")
+        {
+          CHECK(stream.written == "\x1b[2D");
+          CHECK(router.cursor_position() == 0);
+          CHECK(router.max_position() == 2);
+        }
+
+        AND_WHEN("Pressing Home when already at 0")
+        {
+          stream.written.clear();
+          run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::home}));
+
+          THEN("Nothing is emitted")
+          {
+            CHECK(stream.written.empty());
+            CHECK(router.cursor_position() == 0);
+          }
+        }
+
+        AND_WHEN("Pressing End from 0")
+        {
+          stream.written.clear();
+          run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::end}));
+
+          THEN("End moves to max position")
+          {
+            CHECK(stream.written == "\x1b[2C");
+            CHECK(router.cursor_position() == 2);
+            CHECK(router.max_position() == 2);
+          }
+        }
+      }
+
+      AND_WHEN("Pressing Enter")
+      {
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::control_event{ttwhy::terminal::control_key::enter}));
+
+        THEN("Newline is emitted and positions reset")
+        {
+          CHECK(stream.written == "\r\n");
+          CHECK(router.cursor_position() == 0);
+          CHECK(router.max_position() == 0);
+        }
+      }
+
+      AND_WHEN("Pressing Backspace at position 0 after reset")
+      {
+        run_coro(router.process(ttwhy::terminal::control_event{ttwhy::terminal::control_key::enter}));
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::control_event{ttwhy::terminal::control_key::backspace}));
+
+        THEN("Backspace does nothing at position 0")
+        {
+          CHECK(stream.written.empty());
+          CHECK(router.cursor_position() == 0);
+          CHECK(router.max_position() == 0);
+        }
+      }
+
+      AND_WHEN("Using Delete key")
+      {
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::left}));
+        stream.written.clear();
+        run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::delete_key}));
+
+        THEN("Delete character sequence is emitted and max position shrinks")
+        {
+          CHECK(stream.written == "\x1b[P");
+          CHECK(router.cursor_position() == 1);
+          CHECK(router.max_position() == 1);
+        }
+
+        AND_WHEN("Pressing Delete when cursor is at max position")
+        {
+          stream.written.clear();
+          run_coro(router.process(ttwhy::terminal::navigation_event{ttwhy::terminal::navigation_key::delete_key}));
+
+          THEN("Nothing is emitted")
+          {
+            CHECK(stream.written.empty());
+            CHECK(router.cursor_position() == 1);
+            CHECK(router.max_position() == 1);
+          }
+        }
+      }
+    }
+  }
+}