[WIP] parallel test crates

src/bin/cargo/commands/test.rs

@@ -46,6 +46,7 @@ pub fn cli() -> App {
             "Exclude packages from the test",
         )
         .arg_jobs()
+        .arg_test_jobs()
         .arg_release("Build artifacts in release mode, with optimizations")
         .arg_profile("Build artifacts with the specified profile")
         .arg_features()

src/cargo/core/compiler/build_config.rs

@@ -14,6 +14,8 @@ pub struct BuildConfig {
     pub requested_kinds: Vec<CompileKind>,
     /// Number of rustc jobs to run in parallel.
     pub jobs: u32,
+    /// Number of crates to test in parallel.
+    pub test_jobs: u32,
     /// Build profile
     pub requested_profile: InternedString,
     /// The mode we are compiling in.
@@ -53,6 +55,7 @@ impl BuildConfig {
     pub fn new(
         config: &Config,
         jobs: Option<u32>,
+        test_jobs: Option<u32>,
         requested_targets: &[String],
         mode: CompileMode,
     ) -> CargoResult<BuildConfig> {
@@ -72,10 +75,15 @@ impl BuildConfig {
         if jobs == 0 {
             anyhow::bail!("jobs may not be 0");
         }
+        let test_jobs = test_jobs.or(cfg.test_jobs).unwrap_or(1);
+        if test_jobs == 0 {
+            anyhow::bail!("test jobs may not be 0");
+        }
 
         Ok(BuildConfig {
             requested_kinds,
             jobs,
+            test_jobs,
             requested_profile: InternedString::new("dev"),
             mode,
             message_format: MessageFormat::Human,

src/cargo/ops/cargo_compile.rs

@@ -84,7 +84,7 @@ pub struct CompileOptions {
 impl<'a> CompileOptions {
     pub fn new(config: &Config, mode: CompileMode) -> CargoResult<CompileOptions> {
         Ok(CompileOptions {
-            build_config: BuildConfig::new(config, None, &[], mode)?,
+            build_config: BuildConfig::new(config, None, None, &[], mode)?,
             cli_features: CliFeatures::new_all(false),
             spec: ops::Packages::Packages(Vec::new()),
             filter: CompileFilter::Default {

src/cargo/ops/cargo_fetch.rs

@@ -21,7 +21,7 @@ pub fn fetch<'a>(
 
     let jobs = Some(1);
     let config = ws.config();
-    let build_config = BuildConfig::new(config, jobs, &options.targets, CompileMode::Build)?;
+    let build_config = BuildConfig::new(config, jobs, None, &options.targets, CompileMode::Build)?;
     let data = RustcTargetData::new(ws, &build_config.requested_kinds)?;
     let mut fetched_packages = HashSet::new();
     let mut deps_to_fetch = ws.members().map(|p| p.package_id()).collect::<Vec<_>>();

src/cargo/ops/cargo_package.rs

@@ -755,7 +755,13 @@ fn run_verify(
     ops::compile_with_exec(
         &ws,
         &ops::CompileOptions {
-            build_config: BuildConfig::new(config, opts.jobs, &opts.targets, CompileMode::Build)?,
+            build_config: BuildConfig::new(
+                config,
+                opts.jobs,
+                None,
+                &opts.targets,
+                CompileMode::Build,
+            )?,
             cli_features: opts.cli_features.clone(),
             spec: ops::Packages::Packages(Vec::new()),
             filter: ops::CompileFilter::Default {