refactor: Use expected<void, error> instead of optional<error> (#2565)

Co-authored-by: Ayaz Salikhov <mathbunnyru@users.noreply.github.com>

tests/common/util/TestHttpClient.cpp

@@ -186,7 +186,7 @@ HttpAsyncClient::HttpAsyncClient(boost::asio::io_context& ioContext) : stream_{i
 {
 }
 
-std::optional<boost::system::error_code>
+std::expected<void, boost::system::error_code>
 HttpAsyncClient::connect(
     std::string_view host,
     std::string_view port,
@@ -198,18 +198,18 @@ HttpAsyncClient::connect(
     boost::asio::ip::tcp::resolver resolver{stream_.get_executor()};
     auto const resolverResults = resolver.resolve(host, port, error);
     if (error)
-        return error;
+        return std::unexpected{error};
 
     ASSERT(!resolverResults.empty(), "No results from resolver");
 
     boost::beast::get_lowest_layer(stream_).expires_after(timeout);
     stream_.async_connect(resolverResults.begin()->endpoint(), yield[error]);
     if (error)
-        return error;
-    return std::nullopt;
+        return std::unexpected{error};
+    return {};
 }
 
-std::optional<boost::system::error_code>
+std::expected<void, boost::system::error_code>
 HttpAsyncClient::send(
     boost::beast::http::request<boost::beast::http::string_body> request,
     boost::asio::yield_context yield,
@@ -221,8 +221,8 @@ HttpAsyncClient::send(
     boost::beast::get_lowest_layer(stream_).expires_after(timeout);
     http::async_write(stream_, request, yield[error]);
     if (error)
-        return error;
-    return std::nullopt;
+        return std::unexpected{error};
+    return {};
 }
 
 std::expected<boost::beast::http::response<boost::beast::http::string_body>, boost::system::error_code>

tests/common/util/TestHttpClient.hpp

@@ -78,7 +78,7 @@ class HttpAsyncClient {
 public:
     HttpAsyncClient(boost::asio::io_context& ioContext);
 
-    std::optional<boost::system::error_code>
+    std::expected<void, boost::system::error_code>
     connect(
         std::string_view host,
         std::string_view port,
@@ -86,7 +86,7 @@ public:
         std::chrono::steady_clock::duration timeout
     );
 
-    std::optional<boost::system::error_code>
+    std::expected<void, boost::system::error_code>
     send(
         boost::beast::http::request<boost::beast::http::string_body> request,
         boost::asio::yield_context yield,
@@ -98,6 +98,7 @@ public:
 
     void
     gracefulShutdown();
+
     void
     disconnect();
 };

tests/common/util/TestWebSocketClient.cpp

@@ -137,7 +137,7 @@ WebSocketAsyncClient::WebSocketAsyncClient(boost::asio::io_context& ioContext) :
 {
 }
 
-std::optional<boost::system::error_code>
+std::expected<void, boost::system::error_code>
 WebSocketAsyncClient::connect(
     std::string const& host,
     std::string const& port,
@@ -153,7 +153,7 @@ WebSocketAsyncClient::connect(
     boost::beast::get_lowest_layer(stream_).expires_after(timeout);
     stream_.next_layer().async_connect(results, yield[error]);
     if (error)
-        return error;
+        return std::unexpected{error};
 
     boost::beast::websocket::stream_base::timeout wsTimeout =
         boost::beast::websocket::stream_base::timeout::suggested(boost::beast::role_type::client);
@@ -173,12 +173,12 @@ WebSocketAsyncClient::connect(
     stream_.async_handshake(fmt::format("{}:{}", host, port), "/", yield[error]);
 
     if (error)
-        return error;
+        return std::unexpected{error};
 
-    return std::nullopt;
+    return {};
 }
 
-std::optional<boost::system::error_code>
+std::expected<void, boost::system::error_code>
 WebSocketAsyncClient::send(
     boost::asio::yield_context yield,
     std::string_view message,
@@ -190,8 +190,8 @@ WebSocketAsyncClient::send(
     );
 
     if (error)
-        return error;
-    return std::nullopt;
+        return std::unexpected{error};
+    return {};
 }
 
 std::expected<std::string, boost::system::error_code>

tests/common/util/TestWebSocketClient.hpp

@@ -56,7 +56,7 @@ class WebSocketAsyncClient {
 public:
     WebSocketAsyncClient(boost::asio::io_context& ioContext);
 
-    std::optional<boost::system::error_code>
+    std::expected<void, boost::system::error_code>
     connect(
         std::string const& host,
         std::string const& port,
@@ -65,7 +65,7 @@ public:
         std::vector<WebHeader> additionalHeaders = {}
     );
 
-    std::optional<boost::system::error_code>
+    std::expected<void, boost::system::error_code>
     send(boost::asio::yield_context yield, std::string_view message, std::chrono::steady_clock::duration timeout);
 
     std::expected<std::string, boost::system::error_code>