test(aws): trim sleepContext test to the cancellation case only

The happy-path test was a trivial sanity check (sleepContext returns
nil on success). The cancellation case is the one that actually
exercises the new code path. Verbose docstrings removed.

Linear: LIB-4933

Author: james00012

modules/aws/iam_internal_test.go

@@ -7,40 +7,22 @@ import (
 	"time"
 )
 
-// TestSleepContextHonorsCancellation verifies that sleepContext returns promptly
-// with context.Canceled when the context is cancelled mid-sleep, rather than
-// waiting the full duration.
 func TestSleepContextHonorsCancellation(t *testing.T) {
 	t.Parallel()
 
 	ctx, cancel := context.WithCancel(context.Background())
-
-	// Cancel after a short delay so we can verify the sleep is interrupted.
 	go func() {
 		time.Sleep(50 * time.Millisecond)
 		cancel()
 	}()
 
 	start := time.Now()
 	err := sleepContext(ctx, 30*time.Second)
-	elapsed := time.Since(start)
 
 	if !errors.Is(err, context.Canceled) {
 		t.Fatalf("expected context.Canceled, got %v", err)
 	}
-
-	if elapsed > 5*time.Second {
-		t.Fatalf("sleepContext did not return promptly after cancellation; took %v", elapsed)
-	}
-}
-
-// TestSleepContextCompletesNormally verifies that sleepContext returns nil
-// when the duration elapses before the context is cancelled.
-func TestSleepContextCompletesNormally(t *testing.T) {
-	t.Parallel()
-
-	ctx := context.Background()
-	if err := sleepContext(ctx, 10*time.Millisecond); err != nil {
-		t.Fatalf("expected nil error, got %v", err)
+	if time.Since(start) > 5*time.Second {
+		t.Fatalf("sleepContext did not return promptly after cancellation")
 	}
 }