Added C++ smoketest for quickstart-chat + updated chat doc

.github/workflows/ci.yml

@@ -77,6 +77,18 @@ jobs:
         with:
           run_install: true
 
+      # Install cmake and emscripten for C++ module compilation tests.
+      - name: Install cmake and emscripten (Linux)
+        if: runner.os == 'Linux'
+        shell: bash
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y cmake
+          git clone https://github.com/emscripten-core/emsdk.git ~/emsdk
+          cd ~/emsdk
+          ./emsdk install 4.0.21
+          ./emsdk activate 4.0.21
+
       - name: Install psql (Windows)
         if: runner.os == 'Windows'
         run: choco install psql -y --no-progress
@@ -124,7 +136,12 @@ jobs:
         # --test-threads=1 eliminates contention in the C# tests where they fight over bindings
         # build artifacts.
         # It also seemed to improve performance a fair amount (11m -> 6m)
-        run: cargo ci smoketests -- --test-threads=1
+        shell: bash
+        run: |
+          if [ "${{ runner.os }}" = "Linux" ]; then
+            source ~/emsdk/emsdk_env.sh
+          fi
+          cargo ci smoketests -- --test-threads=1
 
   smoketests-python:
     needs: [lints]

crates/smoketests/src/lib.rs

@@ -139,6 +139,15 @@ macro_rules! require_pnpm {
     };
 }
 
+#[macro_export]
+macro_rules! require_emscripten {
+    () => {
+        if !$crate::have_emscripten() {
+            panic!("emcc (Emscripten) not found");
+        }
+    };
+}
+
 /// Helper macro for timing operations and printing results
 macro_rules! timed {
     ($label:expr, $expr:expr) => {{
@@ -242,6 +251,12 @@ pub fn pnpm_path() -> Option<PathBuf> {
     PNPM_PATH.get_or_init(|| which("pnpm").ok()).clone()
 }
 
+/// Returns true if Emscripten (emcc) is available on the system.
+pub fn have_emscripten() -> bool {
+    static HAVE_EMSCRIPTEN: OnceLock<bool> = OnceLock::new();
+    *HAVE_EMSCRIPTEN.get_or_init(|| which("emcc").is_ok() || which("emcc.bat").is_ok())
+}
+
 /// A smoketest instance that manages a SpacetimeDB server and module project.
 pub struct Smoketest {
     /// The SpacetimeDB server guard (stops server on drop).

crates/smoketests/tests/smoketests/quickstart.rs

@@ -4,7 +4,7 @@
 
 use anyhow::{bail, Context, Result};
 use regex::Regex;
-use spacetimedb_smoketests::{pnpm_path, require_dotnet, require_pnpm, workspace_root, Smoketest};
+use spacetimedb_smoketests::{pnpm_path, require_dotnet, require_emscripten, require_pnpm, workspace_root, Smoketest};
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
@@ -438,6 +438,37 @@ fn user_input_direct(ctx: &DbConnection) {
     std::thread::sleep(std::time::Duration::from_secs(1));
     std::process::exit(0);
 }
+"#,
+            connected_str: "connected",
+        }
+    }
+
+    fn cpp() -> Self {
+        // C++ server uses Rust client (same as TypeScript pattern)
+        Self {
+            lang: "cpp",
+            client_lang: "rust",
+            server_file: "src/lib.cpp",
+            client_file: "src/main.rs",
+            module_bindings: "src/module_bindings",
+            run_cmd: &["cargo", "run"],
+            build_cmd: &["cargo", "build"],
+            replacements: &[
+                ("user_input_loop(&ctx)", "user_input_direct(&ctx)"),
+                (".with_token(creds_store()", "//.with_token(creds_store()"),
+            ],
+            extra_code: r#"
+fn user_input_direct(ctx: &DbConnection) {
+    let mut line = String::new();
+    std::io::stdin().read_line(&mut line).expect("Failed to read from stdin.");
+    if let Some(name) = line.strip_prefix("/name ") {
+        ctx.reducers.set_name(name.to_string()).unwrap();
+    } else {
+        ctx.reducers.send_message(line).unwrap();
+    }
+    std::thread::sleep(std::time::Duration::from_secs(1));
+    std::process::exit(0);
+}
 "#,
             connected_str: "connected",
         }
@@ -782,3 +813,12 @@ fn test_quickstart_typescript() {
     let mut qt = QuickstartTest::new(QuickstartConfig::typescript());
     qt.run_quickstart().expect("TypeScript quickstart test failed");
 }
+
+/// Run the C++ quickstart for server (with Rust client).
+#[test]
+fn test_quickstart_cpp() {
+    require_emscripten!();
+
+    let mut qt = QuickstartTest::new(QuickstartConfig::cpp());
+    qt.run_quickstart().expect("C++ quickstart test failed");
+}