Initial project import

tools/v/vlib/mcp/mcp_test.v

@@ -0,0 +1,157 @@
+module mcp
+
+struct MockTransport {
+mut:
+	incoming []string
+	sent     []string
+	closed   bool
+}
+
+fn (mut transport MockTransport) send(message string) ! {
+	transport.sent << message
+}
+
+fn (mut transport MockTransport) receive() !string {
+	if transport.incoming.len == 0 {
+		return error('no messages queued in MockTransport')
+	}
+	message := transport.incoming[0]
+	transport.incoming = if transport.incoming.len == 1 {
+		[]string{}
+	} else {
+		transport.incoming[1..].clone()
+	}
+	return message
+}
+
+fn (mut transport MockTransport) close() {
+	transport.closed = true
+}
+
+fn test_initialize_sends_the_mcp_handshake() {
+	mut transport := &MockTransport{
+		incoming: [
+			new_response(1, InitializeResult{
+				protocol_version: protocol_version
+				capabilities:     '{"tools":{}}'
+				server_info:      Implementation{
+					name:    'mock-server'
+					version: '1.0.0'
+				}
+			}, ResponseError{}).encode(),
+		]
+	}
+	mut client := new_client(transport, ClientConfig{
+		client_info:  Implementation{
+			name:    'mcp-test-client'
+			version: '0.1.0'
+		}
+		capabilities: '{"roots":{"listChanged":true}}'
+	})
+
+	result := client.initialize()!
+
+	assert result.server_info.name == 'mock-server'
+	assert transport.sent.len == 2
+
+	request := decode_request(transport.sent[0])!
+	params := request.decode_params[InitializeParams]()!
+	assert request.method == 'initialize'
+	assert params.protocol_version == protocol_version
+	assert params.client_info.name == 'mcp-test-client'
+	assert params.capabilities == '{"roots":{"listChanged":true}}'
+
+	notification := decode_notification(transport.sent[1])!
+	assert notification.method == 'notifications/initialized'
+	assert notification.params == ''
+}
+
+fn test_request_buffers_server_messages_after_initialize() {
+	mut transport := &MockTransport{
+		incoming: [
+			new_response(1, InitializeResult{
+				protocol_version: protocol_version
+				capabilities:     '{"tools":{}}'
+				server_info:      Implementation{
+					name:    'mock-server'
+					version: '1.0.0'
+				}
+			}, ResponseError{}).encode(),
+			new_notification('notifications/tools/list_changed', empty).encode(),
+			new_request('server-1', 'roots/list', empty).encode(),
+			new_response(2, true, ResponseError{}).encode(),
+		]
+	}
+	mut client := new_client(transport, ClientConfig{})
+	client.initialize()!
+
+	response := client.request_message('ping', empty)!
+
+	assert response.result == 'true'
+	assert transport.sent.len == 3
+	assert decode_request(transport.sent[2])!.method == 'ping'
+
+	notifications := client.take_notifications()
+	assert notifications.len == 1
+	assert notifications[0].method == 'notifications/tools/list_changed'
+
+	requests := client.take_requests()
+	assert requests.len == 1
+	assert requests[0].method == 'roots/list'
+	assert requests[0].id == '"server-1"'
+}
+
+fn test_parse_sse_messages_reads_json_rpc_events() {
+	body := 'event: message\r\n' +
+		'data: {"jsonrpc":"2.0","method":"notifications/progress","params":{"progress":0.5}}\r\n' +
+		'\r\n' + 'event: message\r\n' + 'data: {"jsonrpc":"2.0","id":1,"result":true}\r\n' + '\r\n'
+
+	messages := parse_sse_messages(body)!
+
+	assert messages.len == 2
+	assert decode_notification(messages[0])!.method == 'notifications/progress'
+	assert decode_response(messages[1])!.result == 'true'
+}
+
+fn test_stdio_messages_handle_partial_reads() {
+	payload := new_notification('notifications/initialized', empty).encode()
+	frame := encode_stdio_message(payload)
+	assert frame.ends_with('\n')
+	mut buffer := frame[..frame.len - 1]
+
+	try_extract_stdio_message(buffer) or { assert err.msg() == NoFrameError{}.msg() }
+
+	buffer += frame[frame.len - 1..]
+	extracted := try_extract_stdio_message(buffer)!
+	buffer = extracted.remaining
+	message := extracted.message
+
+	assert buffer == ''
+	assert decode_notification(message)!.method == 'notifications/initialized'
+}
+
+fn test_stdio_messages_strip_embedded_newlines() {
+	payload := '{"jsonrpc":"2.0",\n"method":"ping"}'
+	frame := encode_stdio_message(payload)
+	assert frame == '{"jsonrpc":"2.0","method":"ping"}\n'
+}
+
+fn test_stdio_messages_skip_blank_lines() {
+	first := encode_stdio_message(new_notification('a', empty).encode())
+	second := encode_stdio_message(new_notification('b', empty).encode())
+	buffer := first + '\n\n' + second
+
+	frame_a := try_extract_stdio_message(buffer)!
+	assert decode_notification(frame_a.message)!.method == 'a'
+	frame_b := try_extract_stdio_message(frame_a.remaining)!
+	assert decode_notification(frame_b.message)!.method == 'b'
+}
+
+fn test_close_delegates_to_the_transport() {
+	mut transport := &MockTransport{}
+	mut client := new_client(transport, ClientConfig{})
+
+	client.close()
+
+	assert transport.closed
+}