ruby-sdk/test/mcp/client_test.rb
Koichi ITO c43ea6e51b
Merge pull request #433 from koic/mrtr_result_type
Recognize multi round-trip `input_required` results per SEP-2322
2026-07-12 02:15:01 +09:00

1588 lines
57 KiB
Ruby

# frozen_string_literal: true
require "test_helper"
require "securerandom"
module MCP
class ClientTest < Minitest::Test
def test_connect_delegates_to_transport_and_forwards_keyword_args
transport = mock
init_result = {
"protocolVersion" => "2025-11-25",
"capabilities" => { "tools" => {} },
"serverInfo" => { "name" => "test-server", "version" => "1.0" },
}
transport.expects(:connect).with(
client_info: { name: "my-app", version: "1.0" },
protocol_version: "2025-11-25",
capabilities: { roots: {} },
).returns(init_result).once
result = Client.new(transport: transport).connect(
client_info: { name: "my-app", version: "1.0" },
protocol_version: "2025-11-25",
capabilities: { roots: {} },
)
assert_equal(init_result, result)
end
def test_connect_passes_nil_defaults_to_transport
transport = mock
transport.expects(:connect)
.with(client_info: nil, protocol_version: nil, capabilities: {})
.returns({ "protocolVersion" => "2025-11-25" }).once
Client.new(transport: transport).connect
end
def test_connect_is_noop_when_transport_does_not_respond_to_connect
transport = mock
transport.stubs(:respond_to?).with(:connect).returns(false)
transport.stubs(:respond_to?).with(:server_info).returns(false)
client = Client.new(transport: transport)
assert_nil(client.connect)
assert_nil(client.server_info)
end
def test_connected_delegates_to_transport_when_supported
transport = mock
transport.expects(:connected?).returns(true)
assert_predicate(Client.new(transport: transport), :connected?)
end
def test_connected_returns_true_when_transport_does_not_respond_to_connected
transport = mock
transport.stubs(:respond_to?).with(:connected?).returns(false)
assert_predicate(Client.new(transport: transport), :connected?)
end
def test_server_info_delegates_to_transport_when_supported
transport = mock
init_result = { "protocolVersion" => "2025-11-25" }
transport.expects(:server_info).returns(init_result)
assert_equal(init_result, Client.new(transport: transport).server_info)
end
def test_server_info_returns_nil_when_transport_does_not_expose_it
transport = mock
transport.stubs(:respond_to?).with(:server_info).returns(false)
assert_nil(Client.new(transport: transport).server_info)
end
def test_tools_sends_request_to_transport_and_returns_tools_array
transport = mock
mock_response = {
"result" => {
"tools" => [
{
"name" => "tool1",
"description" => "tool1",
"inputSchema" => {},
"outputSchema" => { "type" => "object", "properties" => { "result" => { "type" => "string" } } },
},
{ "name" => "tool2", "description" => "tool2", "inputSchema" => {} },
],
},
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/list" && args.dig(:request, :jsonrpc) == "2.0"
end.returns(mock_response).once
client = Client.new(transport: transport)
tools = client.tools
assert_equal(2, tools.size)
assert_equal("tool1", tools.first.name)
assert_equal({ "type" => "object", "properties" => { "result" => { "type" => "string" } } }, tools.first.output_schema)
assert_equal("tool2", tools.last.name)
assert_nil(tools.last.output_schema)
end
def test_tools_returns_empty_array_when_no_tools
transport = mock
mock_response = { "result" => { "tools" => [] } }
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/list" && args.dig(:request, :jsonrpc) == "2.0"
end.returns(mock_response).once
client = Client.new(transport: transport)
tools = client.tools
assert_equal([], tools)
end
def test_call_tool_sends_request_to_transport_and_returns_content
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
arguments = { foo: "bar" }
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/call" &&
args.dig(:request, :jsonrpc) == "2.0" &&
args.dig(:request, :params, :name) == "tool1" &&
args.dig(:request, :params, :arguments) == arguments
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.call_tool(tool: tool, arguments: arguments)
content = result.dig("result", "content")
assert_equal([{ type: "text", text: "Hello, world!" }], content)
end
def test_call_tool_by_name
transport = mock
arguments = { foo: "bar" }
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
args.dig(:request, :params, :name) == "tool1" &&
args.dig(:request, :params, :arguments) == arguments
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.call_tool(name: "tool1", arguments: arguments)
content = result.dig("result", "content")
assert_equal([{ type: "text", text: "Hello, world!" }], content)
end
def test_call_tool_raises_input_required_error_when_result_type_is_input_required
# Per SEP-2322, a result with `resultType: "input_required"` is not a final result;
# surface it instead of returning it as a normal result.
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
mock_response = {
"result" => {
"resultType" => "input_required",
"inputRequests" => {
"1" => { "method" => "elicitation/create", "params" => { "mode" => "form", "message" => "Name?" } },
},
"requestState" => "opaque-state",
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::InputRequiredError) do
client.call_tool(tool: tool, arguments: {})
end
assert_equal(
{ "1" => { "method" => "elicitation/create", "params" => { "mode" => "form", "message" => "Name?" } } },
error.input_requests,
)
assert_equal("opaque-state", error.request_state)
assert_equal(mock_response["result"], error.result)
end
def test_call_tool_returns_normally_when_result_type_is_complete
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
mock_response = {
"result" => {
"resultType" => "complete",
"content" => [{ "type" => "text", "text" => "done" }],
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.call_tool(tool: tool, arguments: {})
assert_equal("done", result.dig("result", "content", 0, "text"))
end
def test_call_tool_returns_normally_when_result_type_is_absent
# Regression guard: stable-protocol servers never send `resultType`.
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
mock_response = {
"result" => { "content" => [{ "type" => "text", "text" => "done" }] },
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.call_tool(tool: tool, arguments: {})
assert_equal("done", result.dig("result", "content", 0, "text"))
end
def test_list_tools_raises_input_required_error_for_input_required_results
# The recognition lives in the shared request path, so every client method is covered, not only tools/call.
transport = mock
mock_response = {
"result" => { "resultType" => "input_required", "inputRequests" => {} },
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
assert_raises(Client::InputRequiredError) { client.list_tools }
end
def test_call_tool_raises_when_no_name_or_tool
client = Client.new(transport: mock)
error = assert_raises(ArgumentError) { client.call_tool(arguments: { foo: "bar" }) }
assert_equal("Either `name:` or `tool:` must be provided.", error.message)
end
def test_resources_sends_request_to_transport_and_returns_resources_array
transport = mock
mock_response = {
"result" => {
"resources" => [
{ "name" => "resource1", "uri" => "file:///path/to/resource1", "description" => "First resource" },
{ "name" => "resource2", "uri" => "file:///path/to/resource2", "description" => "Second resource" },
],
},
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "resources/list" && args.dig(:request, :jsonrpc) == "2.0"
end.returns(mock_response).once
client = Client.new(transport: transport)
resources = client.resources
assert_equal(2, resources.size)
assert_equal("resource1", resources.first["name"])
assert_equal("file:///path/to/resource1", resources.first["uri"])
assert_equal("resource2", resources.last["name"])
assert_equal("file:///path/to/resource2", resources.last["uri"])
end
def test_resources_returns_empty_array_when_no_resources
transport = mock
mock_response = { "result" => { "resources" => [] } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
resources = client.resources
assert_equal([], resources)
end
def test_read_resource_sends_request_to_transport_and_returns_contents
transport = mock
uri = "file:///path/to/resource.txt"
mock_response = {
"result" => {
"contents" => [
{ "uri" => uri, "mimeType" => "text/plain", "text" => "Hello, world!" },
],
},
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "resources/read" &&
args.dig(:request, :jsonrpc) == "2.0" &&
args.dig(:request, :params, :uri) == uri
end.returns(mock_response).once
client = Client.new(transport: transport)
contents = client.read_resource(uri: uri)
assert_equal(1, contents.size)
assert_equal(uri, contents.first["uri"])
assert_equal("text/plain", contents.first["mimeType"])
assert_equal("Hello, world!", contents.first["text"])
end
def test_read_resource_returns_empty_array_when_no_contents
transport = mock
uri = "file:///path/to/nonexistent.txt"
mock_response = { "result" => {} }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
contents = client.read_resource(uri: uri)
assert_equal([], contents)
end
def test_resource_templates_sends_request_to_transport_and_returns_resource_templates_array
transport = mock
mock_response = {
"result" => {
"resourceTemplates" => [
{ "name" => "template1", "uriTemplate" => "file:///path/{filename}", "description" => "First template" },
{ "name" => "template2", "uriTemplate" => "http://example.com/{id}", "description" => "Second template" },
],
},
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "resources/templates/list" && args.dig(:request, :jsonrpc) == "2.0"
end.returns(mock_response).once
client = Client.new(transport: transport)
resource_templates = client.resource_templates
assert_equal(2, resource_templates.size)
assert_equal("template1", resource_templates.first["name"])
assert_equal("file:///path/{filename}", resource_templates.first["uriTemplate"])
assert_equal("template2", resource_templates.last["name"])
assert_equal("http://example.com/{id}", resource_templates.last["uriTemplate"])
end
def test_resource_templates_returns_empty_array_when_no_resource_templates
transport = mock
mock_response = { "result" => { "resourceTemplates" => [] } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
resource_templates = client.resource_templates
assert_equal([], resource_templates)
end
def test_prompts_sends_request_to_transport_and_returns_prompts_array
transport = mock
mock_response = {
"result" => {
"prompts" => [
{
"name" => "prompt_1",
"description" => "First prompt",
"arguments" => [
{
"name" => "code_1",
"description" => "The code_1 to review",
"required" => true,
},
],
},
{
"name" => "prompt_2",
"description" => "Second prompt",
"arguments" => [
{
"name" => "code_2",
"description" => "The code_2 to review",
"required" => true,
},
],
},
],
},
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "prompts/list" && args.dig(:request, :jsonrpc) == "2.0"
end.returns(mock_response).once
client = Client.new(transport: transport)
prompts = client.prompts
assert_equal(2, prompts.size)
assert_equal("prompt_1", prompts.first["name"])
assert_equal("First prompt", prompts.first["description"])
assert_equal("code_1", prompts.first["arguments"].first["name"])
assert_equal("The code_1 to review", prompts.first["arguments"].first["description"])
assert(prompts.first["arguments"].first["required"])
assert_equal("prompt_2", prompts.last["name"])
assert_equal("Second prompt", prompts.last["description"])
assert_equal("code_2", prompts.last["arguments"].first["name"])
assert_equal("The code_2 to review", prompts.last["arguments"].first["description"])
assert(prompts.last["arguments"].first["required"])
end
def test_prompts_returns_empty_array_when_no_prompts
transport = mock
mock_response = { "result" => { "prompts" => [] } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
prompts = client.prompts
assert_equal([], prompts)
end
def test_get_prompt_sends_request_to_transport_and_returns_contents
transport = mock
name = "first_prompt"
mock_response = {
"result" => {
"description" => "First prompt",
"messages" => [
{
"role" => "user",
"content" => {
"text" => "First prompt content",
"type" => "text",
},
},
],
},
}
# Only checking for the essential parts of the request
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "prompts/get" &&
args.dig(:request, :jsonrpc) == "2.0" &&
args.dig(:request, :params, :name) == name
end.returns(mock_response).once
client = Client.new(transport: transport)
contents = client.get_prompt(name: name)
assert_equal("First prompt", contents["description"])
assert_equal("user", contents["messages"].first["role"])
assert_equal("First prompt content", contents["messages"].first["content"]["text"])
end
def test_get_prompt_returns_empty_hash_when_no_contents
transport = mock
name = "nonexistent_prompt"
mock_response = { "result" => {} }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
contents = client.get_prompt(name: name)
assert_equal({}, contents)
end
def test_get_prompt_returns_empty_hash
transport = mock
name = "nonexistent_prompt"
mock_response = {}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
contents = client.get_prompt(name: name)
assert_equal({}, contents)
end
def test_call_tool_includes_meta_progress_token_when_provided
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
arguments = { foo: "bar" }
progress_token = "my-progress-token"
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/call" &&
args.dig(:request, :params, :_meta, :progressToken) == progress_token &&
args.dig(:request, :params, :name) == "tool1" &&
args.dig(:request, :params, :arguments) == arguments
end.returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: arguments, progress_token: progress_token)
end
def test_call_tool_sends_trace_context_meta_entries
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
meta = {
MCP::TraceContext::TRACEPARENT_META_KEY => "00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01",
MCP::TraceContext::TRACESTATE_META_KEY => "vendor=value",
MCP::TraceContext::BAGGAGE_META_KEY => "userId=alice",
}
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
sent_meta = args.dig(:request, :params, :_meta)
sent_meta["traceparent"] == meta["traceparent"] &&
sent_meta["tracestate"] == meta["tracestate"] &&
sent_meta["baggage"] == meta["baggage"]
end.returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: {}, meta: meta)
end
def test_call_tool_merges_meta_with_progress_token_taking_precedence
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
meta = { "traceparent" => "00-trace-span-01", "progressToken" => "from-meta" }
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
sent_meta = args.dig(:request, :params, :_meta)
sent_meta["traceparent"] == "00-trace-span-01" &&
sent_meta[:progressToken] == "explicit-token" &&
!sent_meta.key?("progressToken")
end.returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: {}, progress_token: "explicit-token", meta: meta)
end
def test_call_tool_omits_meta_when_empty_meta_hash_given
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
args.dig(:request, :params).key?(:_meta) == false
end.returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: {}, meta: {})
end
def test_call_tool_does_not_mutate_caller_meta
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
meta = { "traceparent" => "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01" }
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: {}, progress_token: "t", meta: meta)
assert_equal({ "traceparent" => "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01" }, meta)
end
def test_read_resource_sends_meta_when_provided
transport = mock
traceparent = "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01"
mock_response = { "result" => { "contents" => [] } }
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "resources/read" &&
args.dig(:request, :params, :uri) == "file:///foo" &&
args.dig(:request, :params, :_meta, :traceparent) == traceparent
end.returns(mock_response).once
client = Client.new(transport: transport)
client.read_resource(uri: "file:///foo", meta: { traceparent: traceparent })
end
def test_request_methods_send_meta_when_provided
# Per SEP-414, trace context should flow on every request, so the `meta:` keyword
# is available on all client request methods.
traceparent = "00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01"
meta = { traceparent: traceparent }
[
["tools/list", { "tools" => [] }, ->(client) { client.list_tools(meta: meta) }],
["resources/list", { "resources" => [] }, ->(client) { client.list_resources(meta: meta) }],
["resources/templates/list", { "resourceTemplates" => [] }, ->(client) { client.list_resource_templates(meta: meta) }],
["prompts/list", { "prompts" => [] }, ->(client) { client.list_prompts(meta: meta) }],
["prompts/get", {}, ->(client) { client.get_prompt(name: "p", meta: meta) }],
[
"completion/complete",
{ "completion" => { "values" => [] } },
->(client) {
client.complete(ref: { type: "ref/prompt", name: "p" }, argument: { name: "a", value: "v" }, meta: meta)
},
],
["ping", {}, ->(client) { client.ping(meta: meta) }],
].each do |method, result, invoke|
transport = mock
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == method &&
args.dig(:request, :params, :_meta, :traceparent) == traceparent
end.returns({ "result" => result }).once
invoke.call(Client.new(transport: transport))
end
end
def test_request_methods_omit_meta_when_not_provided
# Wire-format regression: without `meta:`, list requests keep sending no `params` at all.
transport = mock
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/list" && !args[:request].key?(:params)
end.returns({ "result" => { "tools" => [] } }).once
Client.new(transport: transport).list_tools
end
def test_call_tool_omits_meta_when_no_progress_token
transport = mock
tool = MCP::Client::Tool.new(name: "tool1", description: "tool1", input_schema: {})
arguments = { foo: "bar" }
mock_response = {
"result" => { "content" => [{ "type": "text", "text": "Hello, world!" }] },
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/call" &&
args.dig(:request, :params, :name) == "tool1" &&
args.dig(:request, :params).key?(:_meta) == false
end.returns(mock_response).once
client = Client.new(transport: transport)
client.call_tool(tool: tool, arguments: arguments)
end
def test_tools_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_601, "message" => "Method not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.tools }
assert_equal(-32_601, error.code)
assert_equal("Method not found", error.message)
end
def test_resources_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_602, "message" => "Invalid params" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.resources }
assert_equal(-32_602, error.code)
end
def test_read_resource_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_602, "message" => "Resource not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
assert_raises(Client::ServerError) { client.read_resource(uri: "file:///missing") }
end
def test_read_resource_surfaces_resource_not_found_code_and_data
# Per SEP-2164, servers report unknown resource URIs with -32602 and
# the URI in the error `data`; the client must expose both unmodified.
transport = mock
mock_response = {
"error" => {
"code" => -32_602,
"message" => "Resource not found: file:///missing.txt",
"data" => { "uri" => "file:///missing.txt" },
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.read_resource(uri: "file:///missing.txt") }
assert_equal(-32_602, error.code)
assert_equal({ "uri" => "file:///missing.txt" }, error.data)
end
def test_get_prompt_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_602, "message" => "Prompt not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
assert_raises(Client::ServerError) { client.get_prompt(name: "missing") }
end
def test_prompts_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_601, "message" => "Method not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
assert_raises(Client::ServerError) { client.prompts }
end
def test_resource_templates_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_601, "message" => "Method not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
assert_raises(Client::ServerError) { client.resource_templates }
end
def test_call_tool_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_602, "message" => "Tool not found" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.call_tool(name: "missing") }
assert_equal(-32_602, error.code)
end
def test_server_error_includes_data_field
transport = mock
mock_response = {
"error" => { "code" => -32_603, "message" => "Internal error", "data" => "extra details" },
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.tools }
assert_equal("extra details", error.data)
end
def test_complete_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_602, "message" => "Invalid params" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.complete(ref: { type: "ref/prompt", name: "missing" }, argument: { name: "arg", value: "" }) }
assert_equal(-32_602, error.code)
end
def test_complete_sends_request_and_returns_completion_result
transport = mock
mock_response = {
"result" => {
"completion" => {
"values" => ["python", "pytorch"],
"hasMore" => false,
},
},
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "completion/complete" &&
args.dig(:request, :jsonrpc) == "2.0" &&
args.dig(:request, :params, :ref) == { type: "ref/prompt", name: "code_review" } &&
args.dig(:request, :params, :argument) == { name: "language", value: "py" } &&
!args.dig(:request, :params).key?(:context)
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.complete(
ref: { type: "ref/prompt", name: "code_review" },
argument: { name: "language", value: "py" },
)
assert_equal(["python", "pytorch"], result["values"])
refute(result["hasMore"])
end
def test_complete_includes_context_when_provided
transport = mock
mock_response = {
"result" => {
"completion" => {
"values" => ["flask"],
"hasMore" => false,
},
},
}
transport.expects(:send_request).with do |args|
args.dig(:request, :params, :context) == { arguments: { language: "python" } }
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.complete(
ref: { type: "ref/prompt", name: "code_review" },
argument: { name: "framework", value: "fla" },
context: { arguments: { language: "python" } },
)
assert_equal(["flask"], result["values"])
end
def test_complete_returns_default_when_result_is_missing
transport = mock
mock_response = { "result" => {} }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.complete(
ref: { type: "ref/prompt", name: "test" },
argument: { name: "arg", value: "" },
)
assert_equal([], result["values"])
refute(result["hasMore"])
end
def test_ping_sends_request_and_returns_empty_hash
transport = mock
mock_response = { "result" => {} }
transport.expects(:send_request).with do |args|
req = args[:request]
req[:method] == "ping" &&
req[:jsonrpc] == "2.0" &&
!req.key?(:params)
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.ping
assert_equal({}, result)
end
def test_ping_raises_server_error_on_error_response
transport = mock
mock_response = { "error" => { "code" => -32_603, "message" => "Internal error" } }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ServerError) { client.ping }
assert_equal(-32_603, error.code)
assert_equal("Internal error", error.message)
end
def test_ping_raises_validation_error_when_result_is_missing
transport = mock
mock_response = {}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ValidationError) { client.ping }
assert_equal("Response validation failed: missing or invalid `result`", error.message)
end
def test_ping_raises_validation_error_when_result_is_wrong_type
transport = mock
mock_response = { "result" => "ok" }
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
error = assert_raises(Client::ValidationError) { client.ping }
assert_equal("Response validation failed: missing or invalid `result`", error.message)
end
def test_ping_propagates_transport_errors
transport = mock
transport_error = StandardError.new("read timeout")
transport.expects(:send_request).raises(transport_error).once
client = Client.new(transport: transport)
error = assert_raises(StandardError) { client.ping }
assert_equal("read timeout", error.message)
end
def test_tools_auto_paginates_across_multiple_pages
transport = mock
page1_response = {
"result" => {
"tools" => [{ "name" => "tool1", "description" => "tool1", "inputSchema" => {} }],
"nextCursor" => "cursor1",
},
}
page2_response = {
"result" => {
"tools" => [{ "name" => "tool2", "description" => "tool2", "inputSchema" => {} }],
},
}
call_count = 0
transport.expects(:send_request).twice.with do |args|
call_count += 1
req = args[:request]
if call_count == 1
req[:method] == "tools/list" && req[:params].nil?
else
req[:method] == "tools/list" && req[:params] == { cursor: "cursor1" }
end
end.returns(page1_response).then.returns(page2_response)
client = Client.new(transport: transport)
tools = client.tools
assert_equal(2, tools.size)
assert_equal("tool1", tools[0].name)
assert_equal("tool2", tools[1].name)
end
def test_list_tools_returns_single_page_with_cursor
transport = mock
mock_response = {
"result" => {
"tools" => [{ "name" => "tool1", "description" => "tool1", "inputSchema" => {} }],
"nextCursor" => "cursor1",
},
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == "tools/list"
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.list_tools
assert_equal(1, result.tools.size)
assert_equal("tool1", result.tools[0].name)
assert_equal("cursor1", result.next_cursor)
end
def test_list_results_expose_ttl_ms_and_cache_scope
# SEP-2549 cache hints are surfaced on every paginated result struct.
[
["tools/list", "tools", :list_tools],
["prompts/list", "prompts", :list_prompts],
["resources/list", "resources", :list_resources],
["resources/templates/list", "resourceTemplates", :list_resource_templates],
].each do |method, items_key, client_method|
transport = mock
mock_response = {
"result" => { items_key => [], "ttlMs" => 5000, "cacheScope" => "private" },
}
transport.expects(:send_request).with do |args|
args.dig(:request, :method) == method
end.returns(mock_response).once
result = Client.new(transport: transport).public_send(client_method)
assert_equal(5000, result.ttl_ms, "#{method} missing ttl_ms")
assert_equal("private", result.cache_scope, "#{method} missing cache_scope")
end
end
def test_list_results_have_nil_cache_hints_when_server_omits_them
transport = mock
mock_response = { "result" => { "tools" => [] } }
transport.expects(:send_request).returns(mock_response).once
result = Client.new(transport: transport).list_tools
assert_nil(result.ttl_ms)
assert_nil(result.cache_scope)
end
def test_list_tools_with_cursor_param
transport = mock
mock_response = {
"result" => {
"tools" => [{ "name" => "tool2", "description" => "tool2", "inputSchema" => {} }],
},
}
transport.expects(:send_request).with do |args|
args.dig(:request, :params) == { cursor: "cursor1" }
end.returns(mock_response).once
client = Client.new(transport: transport)
result = client.list_tools(cursor: "cursor1")
assert_equal(1, result.tools.size)
assert_equal("tool2", result.tools[0].name)
assert_nil(result.next_cursor)
end
def test_resources_auto_paginates_across_multiple_pages
transport = mock
page1_response = {
"result" => {
"resources" => [{ "uri" => "https://a.invalid", "name" => "a" }],
"nextCursor" => "cursor1",
},
}
page2_response = {
"result" => {
"resources" => [{ "uri" => "https://b.invalid", "name" => "b" }],
},
}
transport.expects(:send_request).twice.returns(page1_response).then.returns(page2_response)
client = Client.new(transport: transport)
resources = client.resources
assert_equal(2, resources.size)
assert_equal("a", resources[0]["name"])
assert_equal("b", resources[1]["name"])
end
def test_list_resources_returns_single_page_with_cursor
transport = mock
mock_response = {
"result" => {
"resources" => [{ "uri" => "https://a.invalid", "name" => "a" }],
"nextCursor" => "cursor1",
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.list_resources
assert_equal(1, result.resources.size)
assert_equal("cursor1", result.next_cursor)
end
def test_resource_templates_auto_paginates_across_multiple_pages
transport = mock
page1_response = {
"result" => {
"resourceTemplates" => [{ "uriTemplate" => "https://a.invalid/{id}", "name" => "a" }],
"nextCursor" => "cursor1",
},
}
page2_response = {
"result" => {
"resourceTemplates" => [{ "uriTemplate" => "https://b.invalid/{id}", "name" => "b" }],
},
}
transport.expects(:send_request).twice.returns(page1_response).then.returns(page2_response)
client = Client.new(transport: transport)
templates = client.resource_templates
assert_equal(2, templates.size)
assert_equal("a", templates[0]["name"])
assert_equal("b", templates[1]["name"])
end
def test_list_resource_templates_returns_single_page_with_cursor
transport = mock
mock_response = {
"result" => {
"resourceTemplates" => [{ "uriTemplate" => "https://a.invalid/{id}", "name" => "a" }],
"nextCursor" => "cursor1",
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.list_resource_templates
assert_equal(1, result.resource_templates.size)
assert_equal("cursor1", result.next_cursor)
end
def test_prompts_auto_paginates_across_multiple_pages
transport = mock
page1_response = {
"result" => {
"prompts" => [{ "name" => "prompt_a", "description" => "A" }],
"nextCursor" => "cursor1",
},
}
page2_response = {
"result" => {
"prompts" => [{ "name" => "prompt_b", "description" => "B" }],
},
}
transport.expects(:send_request).twice.returns(page1_response).then.returns(page2_response)
client = Client.new(transport: transport)
prompts = client.prompts
assert_equal(2, prompts.size)
assert_equal("prompt_a", prompts[0]["name"])
assert_equal("prompt_b", prompts[1]["name"])
end
def test_tools_breaks_when_server_returns_same_cursor_repeatedly
transport = mock
stuck_response = {
"result" => {
"tools" => [{ "name" => "tool1", "description" => "tool1", "inputSchema" => {} }],
"nextCursor" => "stuck_cursor",
},
}
# If the server keeps returning the same cursor, the client must not loop forever.
# Expect at most 2 calls: the initial request (cursor=nil) and one retry (cursor="stuck_cursor")
# that detects the repeat and breaks out.
transport.expects(:send_request).twice.returns(stuck_response)
client = Client.new(transport: transport)
tools = client.tools
assert_equal(2, tools.size)
end
def test_tools_breaks_when_server_cycles_between_cursors
transport = mock
page_a = {
"result" => {
"tools" => [{ "name" => "tool1", "description" => "tool1", "inputSchema" => {} }],
"nextCursor" => "A",
},
}
page_b = {
"result" => {
"tools" => [{ "name" => "tool2", "description" => "tool2", "inputSchema" => {} }],
"nextCursor" => "B",
},
}
# Server cycles A -> B -> A. Client must detect the revisited cursor and break.
page_a_again = {
"result" => {
"tools" => [{ "name" => "tool3", "description" => "tool3", "inputSchema" => {} }],
"nextCursor" => "A",
},
}
transport.expects(:send_request).times(3).returns(page_a, page_b, page_a_again)
client = Client.new(transport: transport)
tools = client.tools
assert_equal(3, tools.size)
assert_equal(["tool1", "tool2", "tool3"], tools.map(&:name))
end
def test_resources_breaks_when_server_returns_same_cursor_repeatedly
transport = mock
stuck_response = {
"result" => {
"resources" => [{ "uri" => "https://a.invalid", "name" => "a" }],
"nextCursor" => "stuck_cursor",
},
}
transport.expects(:send_request).twice.returns(stuck_response)
client = Client.new(transport: transport)
resources = client.resources
assert_equal(2, resources.size)
end
def test_resource_templates_breaks_when_server_returns_same_cursor_repeatedly
transport = mock
stuck_response = {
"result" => {
"resourceTemplates" => [{ "uriTemplate" => "https://a.invalid/{id}", "name" => "a" }],
"nextCursor" => "stuck_cursor",
},
}
transport.expects(:send_request).twice.returns(stuck_response)
client = Client.new(transport: transport)
templates = client.resource_templates
assert_equal(2, templates.size)
end
def test_prompts_breaks_when_server_returns_same_cursor_repeatedly
transport = mock
stuck_response = {
"result" => {
"prompts" => [{ "name" => "prompt_a", "description" => "A" }],
"nextCursor" => "stuck_cursor",
},
}
transport.expects(:send_request).twice.returns(stuck_response)
client = Client.new(transport: transport)
prompts = client.prompts
assert_equal(2, prompts.size)
end
def test_list_prompts_returns_single_page_with_cursor
transport = mock
mock_response = {
"result" => {
"prompts" => [{ "name" => "prompt_a", "description" => "A" }],
"nextCursor" => "cursor1",
},
}
transport.expects(:send_request).returns(mock_response).once
client = Client.new(transport: transport)
result = client.list_prompts
assert_equal(1, result.prompts.size)
assert_equal("cursor1", result.next_cursor)
end
def test_cancellation_without_reason_omits_reason_in_notification
# The token-driven cancel path must omit `reason` from the `notifications/cancelled` params
# when the token is cancelled without one.
sent = Queue.new
cancellation = MCP::Cancellation.new
transport = Object.new
transport.define_singleton_method(:send_request) do |**|
cancellation.cancel # no reason
{ "result" => {} }
end
transport.define_singleton_method(:send_notification) do |notification:|
sent.push(notification)
nil
end
client = Client.new(transport: transport)
assert_raises(MCP::CancelledError) do
client.call_tool(name: "slow", arguments: {}, cancellation: cancellation)
end
notification = sent.pop
assert_equal(Methods::NOTIFICATIONS_CANCELLED, notification[:method])
refute(notification[:params].key?(:reason))
end
def test_call_tool_with_cancellation_returns_response_when_no_cancel
transport = mock
transport.expects(:send_request).returns({ "result" => { "content" => [{ "type" => "text", "text" => "ok" }] } }).once
transport.stubs(:send_notification) # required for `cancellation:` capability check
cancellation = MCP::Cancellation.new
client = Client.new(transport: transport)
response = client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
assert_equal("ok", response.dig("result", "content", 0, "text"))
end
def test_call_tool_with_cancellation_already_cancelled_raises_without_sending
transport = mock
transport.expects(:send_request).never
transport.expects(:send_notification).never
cancellation = MCP::Cancellation.new
cancellation.cancel(reason: "pre-cancelled")
client = Client.new(transport: transport)
assert_raises(MCP::CancelledError) do
client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
end
end
def test_call_tool_with_cancellation_mid_flight_raises_and_sends_notification
cancellation = MCP::Cancellation.new
notification_queue = Queue.new
transport = Object.new
transport.define_singleton_method(:send_request) do |**|
# Cancel while the request is "in flight".
cancellation.cancel(reason: "user abort")
sleep(0.05)
{ "result" => {} }
end
transport.define_singleton_method(:send_notification) do |notification:|
notification_queue.push(notification)
nil
end
client = Client.new(transport: transport)
error = assert_raises(MCP::CancelledError) do
client.call_tool(name: "slow", arguments: {}, cancellation: cancellation)
end
assert_equal("user abort", error.reason)
# Cancel notification is dispatched fire-and-forget on a separate thread;
# block here until it reaches the transport.
notification = notification_queue.pop
assert_equal(Methods::NOTIFICATIONS_CANCELLED, notification[:method])
assert_equal("user abort", notification[:params][:reason])
end
def test_loop_methods_accept_cancellation_keyword
# Regression: `tools` / `resources` / `resource_templates` / `prompts` are the high-level pagination loops.
# They must accept `cancellation:` so the README's "all request methods accept the cancellation: keyword"
# claim holds. The token is propagated to each underlying `list_*` page.
cancellation = MCP::Cancellation.new
transport = mock
transport.stubs(:send_request).returns({ "result" => { "tools" => [] } })
transport.stubs(:send_notification) # required for `cancellation:` capability check
client = Client.new(transport: transport)
[
-> { client.tools(cancellation: cancellation) },
-> { client.resources(cancellation: cancellation) },
-> { client.resource_templates(cancellation: cancellation) },
-> { client.prompts(cancellation: cancellation) },
].each do |loop_call|
transport.stubs(:send_request).returns({ "result" => {} })
loop_call.call
end
end
def test_cancel_callback_does_not_deadlock_when_transport_holds_a_mutex
# Regression: when the cancellation callback fires on the same thread that is currently inside
# `transport.send_request` (and therefore holds a transport-level mutex), a synchronous `send_notification`
# from the callback would deadlock by re-entering the same mutex. The fix wakes the calling thread first
# and dispatches the notification on a separate thread.
transport_mutex = Mutex.new
cancellation = MCP::Cancellation.new
# Custom transport class so we can model a mutex held during send_request.
transport = Object.new
transport.define_singleton_method(:send_request) do |**|
transport_mutex.synchronize do
# Trigger cancel while we hold the mutex. The callback must NOT try to synchronously acquire
# the same mutex via send_notification.
cancellation.cancel(reason: "mid-flight")
# Hold the mutex briefly to give the callback time to (incorrectly) try to re-enter.
sleep(0.05)
{ "result" => {} }
end
end
# send_notification also needs the mutex - this is the path that would deadlock under synchronous dispatch.
send_notification_called = Queue.new
transport.define_singleton_method(:send_notification) do |notification:|
transport_mutex.synchronize do
send_notification_called.push(notification)
end
end
client = Client.new(transport: transport)
assert_raises(MCP::CancelledError) do
client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
end
# The notification must reach the transport eventually (after the mutex is released by the now-finished send_request).
notification = send_notification_called.pop
assert_equal(Methods::NOTIFICATIONS_CANCELLED, notification[:method])
assert_equal("mid-flight", notification[:params][:reason])
end
def test_late_cancel_after_response_does_not_send_stray_notification
# Regression: between the worker thread pushing `:response` and the main thread leaving `dispatch_with_cancellation`,
# a cancellation firing in that gap must not emit a stray `notifications/cancelled` for the already-completed request.
# The completion-mutex gate makes the worker and the on_cancel callback fight for a single slot; whichever sets
# `completed` first wins, the loser bails.
cancellation = MCP::Cancellation.new
notification_count = 0
notification_count_mutex = Mutex.new
transport = Object.new
transport.define_singleton_method(:send_request) do |**, &on_sent|
on_sent&.call
{ "result" => {} }
end
transport.define_singleton_method(:send_notification) do |**|
notification_count_mutex.synchronize { notification_count += 1 }
nil
end
client = Client.new(transport: transport)
response = client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
assert_equal({}, response["result"])
# Cancel after the call returned. The on_cancel hook was deregistered in the `ensure` block;
# even if a callback raced with the response handoff, `completed` would already be true and
# `queue.push :cancelled` plus the cancel-dispatch thread would not run.
cancellation.cancel(reason: "late")
sleep(0.05) # let any erroneous cancel-dispatch thread complete.
count = notification_count_mutex.synchronize { notification_count }
assert_equal(0, count, "no stray notifications/cancelled for an already-completed request")
end
def test_call_tool_with_cancellation_raises_NoMethodError_when_transport_lacks_send_notification
# Regression: a transport that only implements `send_request` cannot deliver `notifications/cancelled`.
# We must surface this upfront with a clear `NoMethodError` rather than silently swallow
# the failure inside the cancel-dispatch thread - otherwise the user sees `CancelledError` but
# the server never receives the notification.
transport = Object.new
transport.define_singleton_method(:send_request) do |**|
{ "result" => {} }
end
# NOTE: no send_notification.
cancellation = MCP::Cancellation.new
client = Client.new(transport: transport)
error = assert_raises(NoMethodError) do
client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
end
assert_match(/send_notification/, error.message)
end
def test_cancel_notification_is_dispatched_after_request_write_via_on_sent_block
# Regression for the wire-order race: a transport that yields from `send_request` after writing
# the request must see `:request` recorded before `:cancel` even when the cancel signal arrives concurrently.
recorded = []
recorded_mutex = Mutex.new
cancellation = MCP::Cancellation.new
cancel_complete = Queue.new
transport = Object.new
transport.define_singleton_method(:send_request) do |request:, &on_sent|
# Trigger cancel BEFORE the simulated wire-write so the cancel-dispatch thread starts racing immediately.
# The `on_sent` block is yielded only after we have recorded the request - so any cancel-write that obeys
# the block must land afterwards.
cancellation.cancel(reason: "race")
sleep(0.02) # give cancel-dispatch thread time to spawn and start waiting
recorded_mutex.synchronize { recorded << [:request, request[:id]] }
on_sent&.call
{ "result" => {} }
end
transport.define_singleton_method(:send_notification) do |notification:|
recorded_mutex.synchronize { recorded << [:cancel, notification[:params][:requestId]] }
cancel_complete.push(:done)
nil
end
client = Client.new(transport: transport)
client.stubs(:generate_request_id).returns("req-A")
assert_raises(MCP::CancelledError) do
client.call_tool(name: "slow", arguments: {}, cancellation: cancellation)
end
cancel_complete.pop # wait for the fire-and-forget cancel dispatch
# Wire-order must be: request first, then cancel.
assert_equal([[:request, "req-A"], [:cancel, "req-A"]], recorded)
end
def test_cancel_notification_waits_for_delayed_on_sent_signal
# Regression: the cancel-dispatch thread must wait for `&on_sent` no matter how long it takes -
# it cannot fall back to wall-clock-based timeout. An earlier 100 ms fixed-duration fallback
# could release the cancel thread before the worker reached its send-boundary at all, allowing
# the cancel to be issued without any prior request commitment - which the spec only covers under
# the receiver's MAY-ignore-unknown-id clause. The wait is now bounded by worker termination
# (via `ensure -> signal_sent.call`), not by elapsed time.
recorded = []
recorded_mutex = Mutex.new
cancellation = MCP::Cancellation.new
cancel_complete = Queue.new
transport = Object.new
transport.define_singleton_method(:send_request) do |request:, &on_sent|
cancellation.cancel(reason: "race")
# Delay well beyond any plausible fixed-duration fallback (200 ms).
# If cancel-dispatch fires on a timer rather than waiting for on_sent,
# the recorded order will be [:cancel, :request] and the assertion below will fail.
sleep(0.2)
recorded_mutex.synchronize { recorded << [:request, request[:id]] }
on_sent&.call
{ "result" => {} }
end
transport.define_singleton_method(:send_notification) do |notification:|
recorded_mutex.synchronize { recorded << [:cancel, notification[:params][:requestId]] }
cancel_complete.push(:done)
nil
end
client = Client.new(transport: transport)
client.stubs(:generate_request_id).returns("req-D")
assert_raises(MCP::CancelledError) do
client.call_tool(name: "slow", arguments: {}, cancellation: cancellation)
end
cancel_complete.pop
assert_equal([[:request, "req-D"], [:cancel, "req-D"]], recorded)
end
def test_cancel_notification_dispatches_when_worker_raises_before_on_sent
# Regression: if the worker raises before `&on_sent` is called - which can happen if a transport rejects
# a malformed request synchronously - the cancel-dispatch thread must still terminate AND deliver the notification.
# The worker's `ensure` block invokes `signal_sent.call`, which broadcasts to the condition variable and unblocks
# the `until request_sent` wait. Without the ensure-driven unblock, the dispatch thread would leak.
cancellation = MCP::Cancellation.new
send_notification_called = Queue.new
transport = Object.new
transport.define_singleton_method(:send_request) do |**|
# Trigger cancel before raising so the cancel hook fires while the worker is mid-flight,
# then bail out without ever calling on_sent.
cancellation.cancel(reason: "race")
raise StandardError, "transport boom"
end
transport.define_singleton_method(:send_notification) do |notification:|
send_notification_called.push(notification)
nil
end
client = Client.new(transport: transport)
client.stubs(:generate_request_id).returns("req-E")
assert_raises(MCP::CancelledError) do
client.call_tool(name: "slow", arguments: {}, cancellation: cancellation)
end
# The cancel-dispatch thread should still send the notification because the worker's `ensure` triggers `signal_sent.call`.
notification = send_notification_called.pop
assert_equal("req-E", notification[:params][:requestId])
end
def test_call_tool_with_cancellation_normal_completion_does_not_send_notification
transport = mock
transport.expects(:send_request).returns({ "result" => {} }).once
transport.expects(:send_notification).never
cancellation = MCP::Cancellation.new
client = Client.new(transport: transport)
client.call_tool(name: "noop", arguments: {}, cancellation: cancellation)
# Late cancel after normal completion: hook should already be deregistered.
cancellation.cancel(reason: "late")
end
end
end