initial

1 files changed, 70 insertions, 0 deletions

diff --git a/internal/cli/worker_pool_test.go b/internal/cli/worker_pool_test.go
new file mode 100644
index 0000000..db3edf0
--- /dev/null
+++ b/internal/cli/worker_pool_test.go
@@ -0,0 +1,70 @@
+package cli
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+// TestWorkerPoolFailFastSwallowsCancellation locks in the §8.3 invariant that a
+// fail-fast pool reports only GENUINE failures: the first real error cancels the
+// pool, and the in-flight siblings that consequently return context.Canceled are
+// swallowed (cancellation collateral is never an independent per-file failure).
+func TestWorkerPoolFailFastSwallowsCancellation(t *testing.T) {
+	pool := newWorkerPool(context.Background(), 8, true)
+
+	// Occupy several slots with tasks that block until the pool is cancelled and
+	// then return context.Canceled (the collateral that must be swallowed).
+	const blockers = 5
+	for i := 0; i < blockers; i++ {
+		pool.submit("block", func(ctx context.Context) error {
+			<-ctx.Done()
+			return ctx.Err() // context.Canceled
+		})
+	}
+
+	// One genuine failure triggers fail-fast cancellation of the blockers above.
+	pool.submit("fail", func(ctx context.Context) error {
+		return fileError{path: "a.js", err: errors.New("boom")}
+	})
+
+	succeeded, errs := pool.wait()
+	if succeeded != 0 {
+		t.Fatalf("succeeded = %d, want 0", succeeded)
+	}
+	if len(errs) != 1 {
+		t.Fatalf("errs = %d (%v), want exactly 1 genuine failure", len(errs), errs)
+	}
+	if errors.Is(errs[0], context.Canceled) {
+		t.Fatalf("reported error is cancellation collateral, want the genuine failure: %v", errs[0])
+	}
+	var fe fileError
+	if !errors.As(errs[0], &fe) || fe.path != "a.js" {
+		t.Fatalf("reported error = %v, want fileError for a.js", errs[0])
+	}
+}
+
+// TestWorkerPoolDrainReportsAll confirms the non-fail-fast (drain-and-report)
+// mode collects every failure and still runs all tasks.
+func TestWorkerPoolDrainReportsAll(t *testing.T) {
+	pool := newWorkerPool(context.Background(), 4, false)
+
+	const tasks = 6
+	for i := 0; i < tasks; i++ {
+		odd := i%2 == 1
+		pool.submit("t", func(ctx context.Context) error {
+			if odd {
+				return errors.New("fail")
+			}
+			return nil
+		})
+	}
+
+	succeeded, errs := pool.wait()
+	if succeeded != 3 {
+		t.Fatalf("succeeded = %d, want 3", succeeded)
+	}
+	if len(errs) != 3 {
+		t.Fatalf("errs = %d, want 3", len(errs))
+	}
+}