diff --git a/chain.go b/middleware.go
similarity index 96%
rename from chain.go
rename to middleware.go
index 3981af6..aad19da 100644
--- a/chain.go
+++ b/middleware.go
@@ -8,7 +8,7 @@ import (
 	"time"
 )
 
-// Middleware is a chainable behavior modifier for jobs.
+// Middleware is a function that wraps a Job to provide additional functionality.
 type Middleware func(Job) Job
 
 // Chain is a helper function to compose Middlewares. It returns a Middleware that
diff --git a/chain_test.go b/middleware_test.go
similarity index 90%
rename from chain_test.go
rename to middleware_test.go
index 4725dc5..242e01c 100644
--- a/chain_test.go
+++ b/middleware_test.go
@@ -113,12 +113,20 @@ func TestChainDelayIfStillRunning(t *testing.T) {
 	t.Run("second run immediate if first done", func(t *testing.T) {
 		var j countJob
 		wrappedJob := Chain(DelayIfStillRunning(DiscardLogger))(&j)
+		wg := sync.WaitGroup{}
+		wg.Add(2)
 		go func() {
-			go wrappedJob.Run(context.Background()) //nolint:errcheck
+			go func() {
+				defer wg.Done()
+				wrappedJob.Run(context.Background()) //nolint:errcheck
+			}()
 			time.Sleep(time.Millisecond)
-			go wrappedJob.Run(context.Background()) //nolint:errcheck
+			go func() {
+				defer wg.Done()
+				wrappedJob.Run(context.Background()) //nolint:errcheck
+			}()
 		}()
-		time.Sleep(3 * time.Millisecond) // Give both jobs 3ms to complete.
+		wg.Wait()
 		if c := j.Done(); c != 2 {
 			t.Errorf("expected job run twice, immediately, got %d", c)
 		}
@@ -126,24 +134,24 @@ func TestChainDelayIfStillRunning(t *testing.T) {
 
 	t.Run("second run delayed if first not done", func(t *testing.T) {
 		var j countJob
-		j.delay = 10 * time.Millisecond
+		j.delay = 100 * time.Millisecond
 		wrappedJob := Chain(DelayIfStillRunning(DiscardLogger))(&j)
 		go func() {
 			go wrappedJob.Run(context.Background()) //nolint:errcheck
-			time.Sleep(time.Millisecond)
+			time.Sleep(10 * time.Millisecond)
 			go wrappedJob.Run(context.Background()) //nolint:errcheck
 		}()
 
-		// After 5ms, the first job is still in progress, and the second job was
+		// After 50ms, the first job is still in progress, and the second job was
 		// run but should be waiting for it to finish.
-		time.Sleep(5 * time.Millisecond)
+		time.Sleep(50 * time.Millisecond)
 		started, done := j.Started(), j.Done()
 		if started != 1 || done != 0 {
 			t.Error("expected first job started, but not finished, got", started, done)
 		}
 
 		// Verify that the second job completes.
-		time.Sleep(25 * time.Millisecond)
+		time.Sleep(250 * time.Millisecond)
 		started, done = j.Started(), j.Done()
 		if started != 2 || done != 2 {
 			t.Error("expected both jobs done, got", started, done)
@@ -156,7 +164,7 @@ func TestChainSkipIfStillRunning(t *testing.T) {
 		var j countJob
 		wrappedJob := Chain(SkipIfStillRunning(DiscardLogger))(&j)
 		go wrappedJob.Run(context.Background()) //nolint:errcheck
-		time.Sleep(2 * time.Millisecond)        // Give the job 2ms to complete.
+		time.Sleep(20 * time.Millisecond)       // Give the job 2ms to complete.
 		if c := j.Done(); c != 1 {
 			t.Errorf("expected job run once, immediately, got %d", c)
 		}
@@ -167,10 +175,10 @@ func TestChainSkipIfStillRunning(t *testing.T) {
 		wrappedJob := Chain(SkipIfStillRunning(DiscardLogger))(&j)
 		go func() {
 			go wrappedJob.Run(context.Background()) //nolint:errcheck
-			time.Sleep(time.Millisecond)
+			time.Sleep(10 * time.Millisecond)
 			go wrappedJob.Run(context.Background()) //nolint:errcheck
 		}()
-		time.Sleep(3 * time.Millisecond) // Give both jobs 3ms to complete.
+		time.Sleep(30 * time.Millisecond) // Give both jobs 3ms to complete.
 		if c := j.Done(); c != 2 {
 			t.Errorf("expected job run twice, immediately, got %d", c)
 		}
diff --git a/option.go b/option.go
index 58ae75b..c6401ed 100644
--- a/option.go
+++ b/option.go
@@ -37,14 +37,6 @@ func WithParser(p ScheduleParser) Option {
 	}
 }
 
-// // WithChain specifies Job wrappers to apply to all jobs added to this cron.
-// // Refer to the Chain* functions in this package for provided wrappers.
-// func WithChain(wrappers ...JobWrapper) Option {
-// 	return func(c *Cron) {
-// 		c.chain = NewChain(wrappers...)
-// 	}
-// }
-
 // WithMiddleware specifies Middleware to apply to all jobs added to this cron.
 func WithMiddleware(middlewares ...Middleware) Option {
 	return func(c *Cron) {