quickstart-resources/tests/utils.sh
Alex Akimov 470d1ba328
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Fix the tool-use loop in the Go, Rust, and Ruby clients and add a tool-loop smoke test (#200)
* Fix the tool-use loop in the Go, Rust, and Ruby clients and add a tool-loop smoke test

## Motivation and Context

Only the Python and TypeScript clients implemented a correct tool-use loop. The other three
had bugs that break ordinary multi-step requests:

- **Go, Rust, Ruby** did a single tool round and then called Claude once more *without*
  `tools`, so any request that needs a second tool call stalled. Go silently dropped
  `tool_use` blocks from that final response.
- **Ruby** called Claude once per `tool_use` block, each time with a single `tool_result`.
  Parallel tool calls produced a malformed message sequence and an API 400.
- **max_tokens** was 1000 in TypeScript and Ruby, 1024 in Go, and unset in Rust. Sonnet 5
  thinks adaptively, so 1000 tokens is regularly exhausted mid-thought. Python already used
  10000 with a comment explaining why.
- **Ruby** never forwarded MCP `isError` as `is_error`, so the model could not tell a failed
  tool call from a successful one. Rust cannot set the flag either (see below).
- **TypeScript** forwarded raw MCP content blocks to Anthropic. The two block shapes differ,
  so a non-text result would have failed.

The existing smoke test never noticed because it only checks that each client calls
`tools/list`. None of these bugs was reachable without an API key.

### What changed

All five clients now run the same loop: call tools until Claude answers without one, send
every `tool_result` of a turn in one user message, pass `tools` on every call, and stop
after `MAX_TOOL_TURNS = 10`. `max_tokens` is 10000 everywhere, with the same comment.
Python and TypeScript also keep the last response's text when the turn cap is hit; it used
to be dropped.

Rust keeps the `genai` crate. Its tool-response type has no `is_error` field, so an error
result is marked with an `Error:` prefix in the text and the limitation is commented.

### New smoke test

`tests/helpers/tool-loop-test.ts` starts a fake Anthropic Messages API on a loopback port,
points a client at it through `ANTHROPIC_BASE_URL`, pipes in one query, and checks every
request the client sends. It scripts two parallel tool calls, then a call to a tool the mock
server lacks (an `isError` result), then a final answer, and asserts that tools are passed
each time, `max_tokens` is 10000, all `tool_result`s arrive in one message with matching
ids, and the error is forwarded. `smoke-test.sh` runs it for Python, TypeScript, Go, and
Ruby.

The Rust client is excluded for now: `genai` reads no endpoint variable, and the client
negotiates protocol `2025-11-25`, under which the mock's array-rooted tool is refused at call
time. Both will be addressed in a follow-up that brings all examples to current SDK versions.

## How Has This Been Tested?

- `./tests/smoke-test.sh` passes for every example.
- The new tool-loop test passes all 19 checks for Python, TypeScript, Go, and Ruby.
- The Rust client was driven through the same scripted conversation with a temporary
  endpoint resolver (not committed) and passes.
- As a negative check, the Ruby client from `main` was run through the new test. It fails 10
  of 19 checks, on exactly the bugs listed above.
- Go and Ruby were built and run in `golang:1.25` and `ruby:3.4` containers.

## Breaking Changes

None. The clients' command lines, output format, and no-key behavior are unchanged.

## Types of changes

- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
- [x] Documentation update

## Checklist

- [x] I have read the [MCP Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context

Two pre-existing issues surfaced while testing and are left for a follow-up:

- The Rust client (rmcp 3.1.2) negotiates `2025-11-25`. The TypeScript mock server and the
  Python weather server both reject its calls to array-rooted tools under that revision.
  Even current rmcp defaults to `2025-11-25`, so the client must request `2026-07-28`
  explicitly.
- The Go SDK's tool-result helper sends content as a list of text blocks rather than a
  string. The API accepts both, so it is unchanged.

AI assistance: the analysis, code changes, test helper, and this description were prepared
partially manually, partially with Claude Code and reviewed by me.

* Improvements

* Address comments
2026-09-19 18:25:02 -07:00

159 lines
4.6 KiB
Shell

#!/bin/bash
# Shared utilities for test scripts
# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color
# Print functions
print_header() {
echo -e "${YELLOW}==== $1 ====${NC}"
}
print_success() {
echo -e "${GREEN}✓ $1${NC}"
}
print_error() {
echo -e "${RED}✗ $1${NC}"
}
# Get project root directory
get_project_root() {
cd "$(dirname "$0")/.." && pwd
}
# Check if command exists
command_exists() {
command -v "$1" >/dev/null 2>&1
}
# Check dependency and fail the calling test if not found.
#
# Returns rather than exits: a missing toolchain should fail its own test and
# let the rest of the suite run, not abort the whole script before the summary
# is printed.
check_dependency() {
local cmd=$1
if ! command_exists "${cmd}"; then
print_error "${cmd} is not installed"
return 1
fi
}
# The executable suffix for this platform: ".exe" under MSYS/Git Bash, empty
# elsewhere. Windows will not run a binary without it, whatever the file is
# actually named.
exe_suffix() {
case "$(uname -s)" in
MINGW* | MSYS* | CYGWIN*) echo ".exe" ;;
*) echo "" ;;
esac
}
# Echo the path to a built binary, accounting for the .exe suffix on Windows.
# Prints nothing and returns 1 when neither exists.
resolve_binary() {
local path=$1
if [ -f "${path}$(exe_suffix)" ]; then
echo "${path}$(exe_suffix)"
elif [ -f "${path}" ]; then
echo "${path}"
else
return 1
fi
}
# Setup test environment
setup_test() {
local test_name=$1
print_header "Testing ${test_name}"
PROJECT_ROOT=$(get_project_root)
SERVER_DIR="${PROJECT_ROOT}/${test_name}"
CLIENT_DIR="${PROJECT_ROOT}/${test_name}"
TEST_CLIENT="${PROJECT_ROOT}/tests/helpers/build/mcp-test-client.js"
MOCK_SERVER="${PROJECT_ROOT}/tests/helpers/build/mock-mcp-server.js"
TOOL_LOOP_TEST="${PROJECT_ROOT}/tests/helpers/build/tool-loop-test.js"
}
# Ensure test helpers are built
ensure_helpers_built() {
if [ ! -f "${TEST_CLIENT}" ] || [ ! -f "${MOCK_SERVER}" ] || [ ! -f "${TOOL_LOOP_TEST}" ]; then
print_error "Test helpers not built"
print_header "Building test helpers..."
cd "${PROJECT_ROOT}/tests/helpers" || return 1
npm install >/dev/null 2>&1
npm run build >/dev/null 2>&1
cd - >/dev/null || return 1
print_success "Test helpers built"
fi
}
# Run a build step, showing its output only if it fails.
#
# Builds used to be run with `>/dev/null 2>&1` unconditionally, which hid
# compile errors: a failed build left no binary behind and the smoke test
# reported the downstream `spawn ... ENOENT` instead of the actual error.
run_build() {
local what=$1
shift
local output
if ! output=$("$@" 2>&1); then
print_error "${what} failed"
echo "${output}"
return 1
fi
}
# Ensure a project directory is built (TypeScript/Rust/Go)
#
# `bin` is the name of the binary a Rust or Go project produces (unused for
# TypeScript). Rust names it after the package, so it is looked for under
# target/; Go is told to write it to `bin` in the project directory.
#
# Returns rather than exits, for the same reason check_dependency does: one
# project failing to build should fail its own test, not abort the suite
# before the summary is printed.
ensure_built() {
local dir=$1
local bin=$2
cd "${dir}" || return 1
# Install npm dependencies if needed
if [ -f "package.json" ] && [ ! -d "node_modules" ]; then
run_build "npm install in ${dir}" npm install || return 1
fi
# Build TypeScript if needed
if [ -f "tsconfig.json" ] && [ ! -f "build/index.js" ]; then
run_build "npm run build in ${dir}" npm run build || return 1
fi
# Build Rust if needed
if [ -f "Cargo.toml" ] \
&& ! resolve_binary "target/release/${bin}" >/dev/null \
&& ! resolve_binary "target/debug/${bin}" >/dev/null; then
run_build "cargo build in ${dir}" cargo build --release || return 1
fi
# Build Go if needed
if [ -f "go.mod" ] && ! resolve_binary "${bin}" >/dev/null; then
run_build "go build in ${dir}" go build -o "${bin}$(exe_suffix)" . || return 1
fi
}
# Ensure a Ruby project directory has its gems installed.
#
# Unlike ensure_built there is no artefact to test for -- a Ruby example has no
# build step and Gemfile.lock is gitignored -- so ask Bundler directly.
ensure_bundled() {
local dir=$1
cd "${dir}" || return 1
if ! bundle check >/dev/null 2>&1; then
run_build "bundle install in ${dir}" bundle install || return 1
fi
}