From 1ffc580a632ac2bb95ba4f0e815eaac7d8194d4d Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Fri, 29 Sep 2023 23:40:10 +0900
Subject: [PATCH] tests: Allow to run tests in parallel even if the LLVM tool
 is not installed

---
 .github/workflows/ci.yml |  2 +-
 tests/auxiliary/mod.rs   | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dbf42c09..21ee09a0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -64,7 +64,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Install Rust
-        run: rustup toolchain add ${{ matrix.rust }} --no-self-update --component llvm-tools-preview && rustup default ${{ matrix.rust }}
+        run: rustup toolchain add ${{ matrix.rust }} --no-self-update && rustup default ${{ matrix.rust }}
       - run: rustup toolchain add nightly --no-self-update
       - uses: taiki-e/install-action@cargo-hack
       - uses: taiki-e/install-action@cargo-minimal-versions
diff --git a/tests/auxiliary/mod.rs b/tests/auxiliary/mod.rs
index cbdd4b4f..1565ded2 100644
--- a/tests/auxiliary/mod.rs
+++ b/tests/auxiliary/mod.rs
@@ -7,6 +7,7 @@ use std::{
     mem,
     path::{Path, PathBuf},
     process::{Command, ExitStatus, Stdio},
+    sync::OnceLock,
 };
 
 use anyhow::{Context as _, Result};
@@ -19,7 +20,16 @@ pub fn fixtures_path() -> &'static Utf8Path {
     Utf8Path::new(concat!(env!("CARGO_MANIFEST_DIR"), "/tests/fixtures"))
 }
 
+fn ensure_llvm_tools_installed() {
+    static TEST_VERSION: OnceLock<()> = OnceLock::new();
+    TEST_VERSION.get_or_init(|| {
+        // Install component first to avoid component installation conflicts.
+        let _ = Command::new("rustup").args(["component", "add", "llvm-tools-preview"]).output();
+    });
+}
+
 pub fn cargo_llvm_cov(subcommand: &str) -> Command {
+    ensure_llvm_tools_installed();
     let mut cmd = Command::new(env!("CARGO_BIN_EXE_cargo-llvm-cov"));
     cmd.arg("llvm-cov");
     if !subcommand.is_empty() {