Add smoke tests for Go and Rust clients (#196)

* Add smoke tests for Go and Rush clients

* Add smoke tests for Go and Rush clients

tests/README.md

@@ -7,9 +7,7 @@ This directory contains smoke tests for the MCP quickstart examples. These tests
 The smoke tests verify:
 
 - **Servers**: Each weather server (Python, TypeScript, Rust, Go, Ruby) can start, respond to MCP protocol requests, and honour the output schemas it advertises
-- **Clients**: The Python, TypeScript and Ruby MCP clients can connect to a mock server and list tools
-
-The Go and Rust clients are not covered here: on `main` both abort when no `.env` file is present, so they cannot be driven without credentials. Making them start credential-free is a change in their own directories, so their coverage lands with those changes rather than here.
+- **Clients**: Each MCP client (Python, TypeScript, Ruby, Go, Rust) can connect to a mock server and list tools
 
 ## Structured content
 
@@ -64,6 +62,8 @@ Each client test:
 
 **Note**: Client tests run the actual CLI programs without an Anthropic API key. The clients are designed to handle missing API keys gracefully by listing available tools and exiting, which is perfect for smoke testing the MCP connectivity without requiring external API calls.
 
+The key is set to the empty string rather than unset. Every client loads `.env` without overriding variables already in the environment, so an empty value keeps a developer's local `.env` from starting the chat loop, and every client treats an empty key the same as a missing one.
+
 ## Test Helpers
 
 ### mcp-test-client.ts

tests/smoke-test.sh

@@ -48,7 +48,7 @@ test_weather_server_typescript() {
     check_dependency node || return 1
     check_dependency npm || return 1
     local server_dir="${PROJECT_ROOT}/weather-server-typescript"
-    ensure_built "${server_dir}" || return 1
+    ensure_built "${server_dir}" "" || return 1
     node "${TEST_CLIENT}" node "${server_dir}/build/index.js"
 }
 
@@ -56,7 +56,7 @@ test_weather_server_typescript() {
 test_weather_server_rust() {
     check_dependency cargo || return 1
     local server_dir="${PROJECT_ROOT}/weather-server-rust"
-    ensure_built "${server_dir}" || return 1
+    ensure_built "${server_dir}" weather || return 1
 
     # Determine which binary to use
     local server_bin
@@ -73,7 +73,7 @@ test_weather_server_rust() {
 test_weather_server_go() {
     check_dependency go || return 1
     local server_dir="${PROJECT_ROOT}/weather-server-go"
-    ensure_built "${server_dir}" || return 1
+    ensure_built "${server_dir}" server || return 1
 
     local server_bin
     server_bin=$(resolve_binary "${server_dir}/server") || {
@@ -109,7 +109,7 @@ test_mcp_client_typescript() {
     check_dependency node || return 1
     check_dependency npm || return 1
     local client_dir="${PROJECT_ROOT}/mcp-client-typescript"
-    ensure_built "${client_dir}" || return 1
+    ensure_built "${client_dir}" "" || return 1
     ANTHROPIC_API_KEY= node "${client_dir}/build/index.js" "${MOCK_SERVER}" >/dev/null 2>&1
 }
 
@@ -122,12 +122,38 @@ test_mcp_client_ruby() {
     (cd "${client_dir}" && ANTHROPIC_API_KEY= bundle exec ruby client.rb "${MOCK_SERVER}") >/dev/null 2>&1
 }
 
+# Test: Go MCP client
+test_mcp_client_go() {
+    check_dependency go || return 1
+    local client_dir="${PROJECT_ROOT}/mcp-client-go"
+    ensure_built "${client_dir}" mcp-client-go || return 1
+
+    local client_bin
+    client_bin=$(resolve_binary "${client_dir}/mcp-client-go") || {
+        print_error "no mcp-client-go binary found in ${client_dir}"
+        return 1
+    }
+
+    ANTHROPIC_API_KEY= "${client_bin}" node "${MOCK_SERVER}" >/dev/null 2>&1
+}
+
+# Test: Rust MCP client
+test_mcp_client_rust() {
+    check_dependency cargo || return 1
+    local client_dir="${PROJECT_ROOT}/mcp-client-rust"
+    ensure_built "${client_dir}" mcp-client-rust || return 1
+
+    local client_bin
+    client_bin=$(resolve_binary "${client_dir}/target/release/mcp-client-rust" \
+        || resolve_binary "${client_dir}/target/debug/mcp-client-rust") || {
+        print_error "no mcp-client-rust binary found in ${client_dir}/target"
+        return 1
+    }
+
+    ANTHROPIC_API_KEY= "${client_bin}" node "${MOCK_SERVER}" >/dev/null 2>&1
+}
+
 # Run all tests
-#
-# The Go and Rust clients are not covered: on main both abort when no .env file
-# is present, so they cannot be driven without credentials. Making them start
-# credential-free is a change in their own directories, so their coverage lands
-# with those changes rather than here.
 
 print_header "Running smoke tests"
 run_test "weather-server-python" test_weather_server_python
@@ -138,6 +164,8 @@ run_test "weather-server-ruby" test_weather_server_ruby
 run_test "mcp-client-python" test_mcp_client_python
 run_test "mcp-client-typescript" test_mcp_client_typescript
 run_test "mcp-client-ruby" test_mcp_client_ruby
+run_test "mcp-client-go" test_mcp_client_go
+run_test "mcp-client-rust" test_mcp_client_rust
 
 # Print summary
 echo ""

tests/utils.sh

@@ -109,11 +109,16 @@ run_build() {
 
 # 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
@@ -128,14 +133,14 @@ ensure_built() {
 
     # Build Rust if needed
     if [ -f "Cargo.toml" ] \
-        && ! resolve_binary "target/release/weather" >/dev/null \
-        && ! resolve_binary "target/debug/weather" >/dev/null; then
+        && ! 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 "server" >/dev/null; then
-        run_build "go build in ${dir}" go build -o "server$(exe_suffix)" . || return 1
+    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
 }