build jobs

tools/ci/src/args.rs

@@ -1,5 +1,5 @@
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub struct Args {
     pub keep_going: bool,
-    pub test_threads: u8,
+    pub test_threads: Option<u8>,
 }

tools/ci/src/ci.rs

@@ -17,7 +17,11 @@ pub struct CI {
 
     /// parallelism of `cargo test`
     #[argh(option)]
-    test_threads: u8,
+    test_threads: Option<u8>,
+
+    /// sets `RUST_BUILD_JOBS`
+    #[argh(option)]
+    build_jobs: Option<u8>,
 }
 
 impl From<&CI> for Args {
@@ -36,7 +40,14 @@ impl CI {
     /// This is usually related to differing toolchains and configuration.
     pub fn run(self) {
         let sh = xshell::Shell::new().unwrap();
-        let prepared_commands = self.prepare(&sh);
+        let mut prepared_commands = self.prepare(&sh);
+
+        if let Some(build_jobs) = self.build_jobs {
+            prepared_commands = prepared_commands
+                .into_iter()
+                .map(|pc| pc.with_env_var("RUST_BUILD_JOBS", build_jobs.to_string().leak()))
+                .collect();
+        }
         let mut failures = vec![];
 
         for command in prepared_commands {

tools/ci/src/commands/doc_test.rs

@@ -14,12 +14,15 @@ impl Prepare for DocTestCommand {
             .then_some("--no-fail-fast")
             .unwrap_or_default();
 
-        let test_threads = args.test_threads.to_string();
+        let test_threads = args
+            .test_threads
+            .map(|test_threads| format!("--test-threads={test_threads}"))
+            .unwrap_or_default();
 
         vec![PreparedCommand::new::<Self>(
             cmd!(
                 sh,
-                "cargo test --workspace --doc {no_fail_fast} -- --test-threads={test_threads}"
+                "cargo test --workspace --doc {no_fail_fast} -- {test_threads}"
             ),
             "Please fix failing doc tests in output above.",
         )]

tools/ci/src/commands/test.rs

@@ -14,10 +14,15 @@ impl Prepare for TestCommand {
             .then_some("--no-fail-fast")
             .unwrap_or_default();
 
+        let test_threads = args
+            .test_threads
+            .map(|test_threads| format!("--test-threads={test_threads}"))
+            .unwrap_or_default();
+
         vec![PreparedCommand::new::<Self>(
             cmd!(
                 sh,
-                "cargo test --workspace --lib --bins --tests --benches {no_fail_fast}"
+                "cargo test --workspace --lib --bins --tests --benches {no_fail_fast} -- {test_threads}"
             ),
             "Please fix failing tests in output above.",
         )]