From ad19c9cf412ca59c8557eb0972094a6dbf87cce5 Mon Sep 17 00:00:00 2001
From: joshua-spacetime <josh@clockworklabs.io>
Date: Mon, 6 Apr 2026 16:15:15 -0700
Subject: [PATCH] Parallelize smoketests

---
 .config/nextest.toml     | 25 +++++++++++++++++++++++++
 .github/workflows/ci.yml |  8 ++++----
 2 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 .config/nextest.toml

diff --git a/.config/nextest.toml b/.config/nextest.toml
new file mode 100644
index 00000000000..c6aa072721f
--- /dev/null
+++ b/.config/nextest.toml
@@ -0,0 +1,25 @@
+[test-groups]
+# These smoketests rebuild or reconfigure shared TS/C#/C++ toolchain artifacts.
+# Keep them mutually exclusive so the rest of the Rust smoketests can continue
+# to run under nextest's normal parallel execution.
+smoketests-toolchain = { max-threads = 1 }
+
+[[profile.default.overrides]]
+filter = 'package(spacetimedb-smoketests) & test(/^smoketests::csharp_module::/)'
+test-group = 'smoketests-toolchain'
+
+[[profile.default.overrides]]
+filter = 'package(spacetimedb-smoketests) & test(/^smoketests::templates::/)'
+test-group = 'smoketests-toolchain'
+
+[[profile.default.overrides]]
+filter = 'package(spacetimedb-smoketests) & test(/^smoketests::change_host_type::/)'
+test-group = 'smoketests-toolchain'
+
+[[profile.default.overrides]]
+filter = 'package(spacetimedb-smoketests) & test(/^smoketests::quickstart::test_quickstart_(csharp|typescript|cpp)$/)'
+test-group = 'smoketests-toolchain'
+
+[[profile.default.overrides]]
+filter = 'package(spacetimedb-smoketests) & test(/^smoketests::views::test_(csharp|typescript)_/)'
+test-group = 'smoketests-toolchain'
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f9c105f4c4c..51fc639694d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -149,9 +149,9 @@ jobs:
       - name: Install cargo-nextest
         uses: taiki-e/install-action@nextest
 
-      # --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)
+      # In CI this uses cargo-nextest. Keep the libtest harness on a single thread per
+      # test process, and let .config/nextest.toml serialize only the shared TS/C#/C++
+      # smoketests while the Rust smoketests continue to run concurrently.
       - name: Run smoketests (Linux)
         if: runner.os == 'Linux'
         shell: bash
@@ -169,7 +169,7 @@ jobs:
           if (Test-Path "$env:USERPROFILE\emsdk\emsdk_env.ps1") {
             & "$env:USERPROFILE\emsdk\emsdk_env.ps1" | Out-Null
           }
-          cargo ci smoketests -- --test-threads=1          
+          cargo ci smoketests -- --test-threads=1
 
       - name: Check for changes
         run: |