diff --git a/default_context.go b/default_context.go
index 3f2eec99d..e88acbf4b 100644
--- a/default_context.go
+++ b/default_context.go
@@ -23,6 +23,9 @@ import (
 var _ Context = &DefaultContext{}
 var _ context.Context = &DefaultContext{}
 
+// TODO(sio4): #road-to-v1 - make DefaultContext private
+// and only allow it to be generated by App.newContext() or any similar.
+
 // DefaultContext is, as its name implies, a default
 // implementation of the Context interface.
 type DefaultContext struct {
@@ -67,16 +70,22 @@ func (d *DefaultContext) Param(key string) string {
 // Set a value onto the Context. Any value set onto the Context
 // will be automatically available in templates.
 func (d *DefaultContext) Set(key string, value interface{}) {
+	if d.data == nil {
+		d.data = &sync.Map{}
+	}
 	d.data.Store(key, value)
 }
 
 // Value that has previously stored on the context.
 func (d *DefaultContext) Value(key interface{}) interface{} {
-	if k, ok := key.(string); ok {
+	if k, ok := key.(string); ok && d.data != nil {
 		if v, ok := d.data.Load(k); ok {
 			return v
 		}
 	}
+	if d.Context == nil {
+		return nil
+	}
 	return d.Context.Value(key)
 }
 
@@ -235,6 +244,11 @@ func (d *DefaultContext) Redirect(status int, url string, args ...interface{}) e
 // Data contains all the values set through Get/Set.
 func (d *DefaultContext) Data() map[string]interface{} {
 	m := map[string]interface{}{}
+
+	if d.data == nil {
+		return m
+	}
+
 	d.data.Range(func(k, v interface{}) bool {
 		s, ok := k.(string)
 		if !ok {
diff --git a/default_context_test.go b/default_context_test.go
index 2823828cc..203781641 100644
--- a/default_context_test.go
+++ b/default_context_test.go
@@ -143,6 +143,15 @@ func Test_DefaultContext_GetSet(t *testing.T) {
 	r.Equal("Mark", c.Value("name").(string))
 }
 
+func Test_DefaultContext_Set_Unconfigured(t *testing.T) {
+	r := require.New(t)
+	c := DefaultContext{}
+
+	c.Set("name", "Yonghwan")
+	r.NotNil(c.Value("name"))
+	r.Equal("Yonghwan", c.Value("name").(string))
+}
+
 func Test_DefaultContext_Value(t *testing.T) {
 	r := require.New(t)
 	c := basicContext()
@@ -151,7 +160,12 @@ func Test_DefaultContext_Value(t *testing.T) {
 	c.Set("name", "Mark")
 	r.NotNil(c.Value("name"))
 	r.Equal("Mark", c.Value("name").(string))
-	r.Equal("Mark", c.Value("name").(string))
+}
+
+func Test_DefaultContext_Value_Unconfigured(t *testing.T) {
+	r := require.New(t)
+	c := DefaultContext{}
+	r.Nil(c.Value("name"))
 }
 
 func Test_DefaultContext_Render(t *testing.T) {
@@ -301,3 +315,68 @@ func Test_DefaultContext_Bind_JSON(t *testing.T) {
 
 	r.Equal("Mark", user.FirstName)
 }
+
+func Test_DefaultContext_Data(t *testing.T) {
+	r := require.New(t)
+	c := basicContext()
+
+	r.EqualValues(map[string]interface{}{}, c.Data())
+}
+
+func Test_DefaultContext_Data_Unconfigured(t *testing.T) {
+	r := require.New(t)
+	c := DefaultContext{}
+
+	r.EqualValues(map[string]interface{}{}, c.Data())
+}
+
+func Test_DefaultContext_String(t *testing.T) {
+	r := require.New(t)
+	c := basicContext()
+	c.Set("name", "Buffalo")
+	c.Set("language", "go")
+
+	r.EqualValues("language: go\n\nname: Buffalo", c.String())
+}
+
+func Test_DefaultContext_String_EmptyData(t *testing.T) {
+	r := require.New(t)
+	c := basicContext()
+	r.EqualValues("", c.String())
+}
+
+func Test_DefaultContext_String_EmptyData_Unconfigured(t *testing.T) {
+	r := require.New(t)
+	c := DefaultContext{}
+
+	r.EqualValues("", c.String())
+}
+
+func Test_DefaultContext_MarshalJSON(t *testing.T) {
+	r := require.New(t)
+	c := basicContext()
+	c.Set("name", "Buffalo")
+	c.Set("language", "go")
+
+	jb, err := c.MarshalJSON()
+	r.NoError(err)
+	r.EqualValues(`{"language":"go","name":"Buffalo"}`, string(jb))
+}
+
+func Test_DefaultContext_MarshalJSON_EmptyData(t *testing.T) {
+	r := require.New(t)
+	c := basicContext()
+
+	jb, err := c.MarshalJSON()
+	r.NoError(err)
+	r.EqualValues(`{}`, string(jb))
+}
+
+func Test_DefaultContext_MarshalJSON_EmptyData_Unconfigured(t *testing.T) {
+	r := require.New(t)
+	c := DefaultContext{}
+
+	jb, err := c.MarshalJSON()
+	r.NoError(err)
+	r.EqualValues(`{}`, string(jb))
+}
diff --git a/plugins/plugins_test.go b/plugins/plugins_test.go
index 1f6317435..855850a1f 100644
--- a/plugins/plugins_test.go
+++ b/plugins/plugins_test.go
@@ -2,7 +2,7 @@ package plugins
 
 import (
 	"context"
-	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 	"time"
@@ -20,7 +20,7 @@ func TestAskBin_respectsTimeout(t *testing.T) {
 		return
 	}
 
-	if fileEntries, err := ioutil.ReadDir(from); err == nil {
+	if fileEntries, err := os.ReadDir(from); err == nil {
 		found := false
 		for _, e := range fileEntries {
 			if strings.HasPrefix(e.Name(), "buffalo-") {
diff --git a/router_test.go b/router_test.go
index ff3584fa5..29bbdff3b 100644
--- a/router_test.go
+++ b/router_test.go
@@ -2,7 +2,7 @@ package buffalo
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"os"
 	"path"
@@ -98,7 +98,7 @@ func Test_Mount_Buffalo(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, _ := ioutil.ReadAll(res.Body)
+		b, _ := io.ReadAll(res.Body)
 		r.Equal(fmt.Sprintf("%s - %s/", m, u), string(b))
 	}
 }
@@ -123,7 +123,7 @@ func Test_Mount_Buffalo_on_Group(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, _ := ioutil.ReadAll(res.Body)
+		b, _ := io.ReadAll(res.Body)
 		r.Equal(fmt.Sprintf("%s - %s/", m, u), string(b))
 	}
 }
@@ -158,7 +158,7 @@ func Test_Mount_Handler(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, _ := ioutil.ReadAll(res.Body)
+		b, _ := io.ReadAll(res.Body)
 		r.Equal(fmt.Sprintf("%s - %s/", m, u), string(b))
 	}
 }
@@ -197,7 +197,7 @@ func Test_PreHandlers(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, err := ioutil.ReadAll(res.Body)
+		b, err := io.ReadAll(res.Body)
 		r.NoError(err)
 		r.Equal(v.Code, res.StatusCode)
 		r.Equal(v.Result, string(b))
@@ -242,7 +242,7 @@ func Test_PreWares(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, err := ioutil.ReadAll(res.Body)
+		b, err := io.ReadAll(res.Body)
 		r.NoError(err)
 		r.Equal(v.Code, res.StatusCode)
 		r.Equal(v.Result, string(b))
@@ -269,7 +269,7 @@ func Test_Router(t *testing.T) {
 		r.NoError(err)
 		res, err := http.DefaultClient.Do(req)
 		r.NoError(err)
-		b, _ := ioutil.ReadAll(res.Body)
+		b, _ := io.ReadAll(res.Body)
 		r.Equal(fmt.Sprintf("%s|/router/tests", v), string(b))
 	}
 }
@@ -552,7 +552,7 @@ func Test_Resource(t *testing.T) {
 			r.NoError(err)
 			res, err := c.Do(req)
 			r.NoError(err)
-			b, err := ioutil.ReadAll(res.Body)
+			b, err := io.ReadAll(res.Body)
 			r.NoError(err)
 			r.Equal(test.Result, string(b))
 		}
@@ -710,7 +710,7 @@ func Test_ResourceOnResource(t *testing.T) {
 		r.NoError(err)
 		res, err := c.Do(req)
 		r.NoError(err)
-		b, err := ioutil.ReadAll(res.Body)
+		b, err := io.ReadAll(res.Body)
 		r.NoError(err)
 		r.Equal(test.Result, string(b))
 	}
diff --git a/worker/simple.go b/worker/simple.go
index 3f5788d40..76d9ef673 100644
--- a/worker/simple.go
+++ b/worker/simple.go
@@ -15,6 +15,9 @@ var _ Worker = &Simple{}
 // NewSimple creates a basic implementation of the Worker interface
 // that is backed using just the standard library and goroutines.
 func NewSimple() *Simple {
+	// TODO(sio4): #road-to-v1 - how to check if the worker is ready to work
+	// when worker should be initialized? how to check if worker is ready?
+	// and purpose of the context
 	return NewSimpleWithContext(context.Background())
 }
 
@@ -49,6 +52,10 @@ type Simple struct {
 
 // Register Handler with the worker
 func (w *Simple) Register(name string, h Handler) error {
+	if name == "" || h == nil {
+		return fmt.Errorf("name or handler cannot be empty/nil")
+	}
+
 	w.moot.Lock()
 	defer w.moot.Unlock()
 	if _, ok := w.handlers[name]; ok {
@@ -60,6 +67,7 @@ func (w *Simple) Register(name string, h Handler) error {
 
 // Start the worker
 func (w *Simple) Start(ctx context.Context) error {
+	// TODO(sio4): #road-to-v1 - define the purpose of Start clearly
 	w.Logger.Info("starting Simple background worker")
 
 	w.ctx, w.cancel = context.WithCancel(ctx)
@@ -68,20 +76,30 @@ func (w *Simple) Start(ctx context.Context) error {
 
 // Stop the worker
 func (w *Simple) Stop() error {
+	// prevent job submission when stopping
+	w.moot.Lock()
+	defer w.moot.Unlock()
+
 	w.Logger.Info("stopping Simple background worker")
 
+	w.cancel()
+
 	w.wg.Wait()
 	w.Logger.Info("all background jobs stopped completely")
-	w.cancel()
 	return nil
 }
 
 // Perform a job as soon as possibly using a goroutine.
 func (w *Simple) Perform(job Job) error {
+	// Perform should not allow a job submission if the worker is not running
+	if err := w.ctx.Err(); err != nil {
+		return fmt.Errorf("worker is not ready to perform a job: %v", err)
+	}
+
 	w.Logger.Debugf("performing job %s", job)
 
 	if job.Handler == "" {
-		err := fmt.Errorf("no handler name given for %s", job)
+		err := fmt.Errorf("no handler name given: %s", job)
 		w.Logger.Error(err)
 		return err
 	}
@@ -89,7 +107,7 @@ func (w *Simple) Perform(job Job) error {
 	w.moot.Lock()
 	defer w.moot.Unlock()
 	if h, ok := w.handlers[job.Handler]; ok {
-		// TODO: consider to implement timeout and/or cancellation
+		// TODO(sio4): #road-to-v1 - consider timeout and/or cancellation
 		w.wg.Add(1)
 		go func() {
 			defer w.wg.Done()
@@ -118,11 +136,20 @@ func (w *Simple) PerformAt(job Job, t time.Time) error {
 // PerformIn performs a job after waiting for a specified amount
 // using a goroutine.
 func (w *Simple) PerformIn(job Job, d time.Duration) error {
+	// Perform should not allow a job submission if the worker is not running
+	if err := w.ctx.Err(); err != nil {
+		return fmt.Errorf("worker is not ready to perform a job: %v", err)
+	}
+
+	w.wg.Add(1) // waiting job also should be counted
 	go func() {
+		defer w.wg.Done()
+
 		select {
 		case <-time.After(d):
 			w.Perform(job)
 		case <-w.ctx.Done():
+			// TODO(sio4): #road-to-v1 - it should be guaranteed to be performed
 			w.cancel()
 		}
 	}()
diff --git a/worker/simple_test.go b/worker/simple_test.go
index 6372d60ca..7abf0b499 100644
--- a/worker/simple_test.go
+++ b/worker/simple_test.go
@@ -1,6 +1,7 @@
 package worker
 
 import (
+	"context"
 	"sync"
 	"testing"
 	"time"
@@ -8,76 +9,188 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func sampleHandler(Args) error {
+	return nil
+}
+
+func Test_Simple_RegisterEmpty(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	err := w.Register("", sampleHandler)
+	r.Error(err)
+}
+
+func Test_Simple_RegisterNil(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	err := w.Register("sample", nil)
+	r.Error(err)
+}
+
+func Test_Simple_RegisterEmptyNil(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	err := w.Register("", nil)
+	r.Error(err)
+}
+
+func Test_Simple_RegisterExisting(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	err := w.Register("sample", sampleHandler)
+	r.NoError(err)
+
+	err = w.Register("sample", sampleHandler)
+	r.Error(err)
+}
+
+func Test_Simple_StartStop(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	ctx := context.Background()
+	err := w.Start(ctx)
+	r.NoError(err)
+	r.NotNil(w.ctx)
+	r.Nil(w.ctx.Err())
+
+	err = w.Stop()
+	r.NoError(err)
+	r.NotNil(w.ctx)
+	r.NotNil(w.ctx.Err())
+}
+
 func Test_Simple_Perform(t *testing.T) {
 	r := require.New(t)
 
 	var hit bool
-	wg := &sync.WaitGroup{}
-	wg.Add(1)
 	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+
 	w.Register("x", func(Args) error {
 		hit = true
-		wg.Done()
 		return nil
 	})
 	w.Perform(Job{
 		Handler: "x",
 	})
-	wg.Wait()
+
+	// the worker should guarantee the job is finished before the worker stopped
+	r.NoError(w.Stop())
 	r.True(hit)
 }
 
-func Test_Simple_PerformAt(t *testing.T) {
+func Test_Simple_PerformBroken(t *testing.T) {
 	r := require.New(t)
 
 	var hit bool
-	wg := &sync.WaitGroup{}
-	wg.Add(1)
 	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+
 	w.Register("x", func(Args) error {
 		hit = true
-		wg.Done()
+
+		//Index out of bounds on purpose
+		println([]string{}[0])
+
 		return nil
 	})
-	w.PerformAt(Job{
+	w.Perform(Job{
 		Handler: "x",
-	}, time.Now().Add(5*time.Millisecond))
-	wg.Wait()
+	})
+
+	r.NoError(w.Stop())
 	r.True(hit)
 }
 
-func Test_Simple_PerformBroken(t *testing.T) {
+func Test_Simple_PerformWithEmptyJob(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+	defer w.Stop()
+
+	err := w.Perform(Job{})
+	r.Error(err)
+}
+
+func Test_Simple_PerformWithUnknownJob(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+	defer w.Stop()
+
+	err := w.Perform(Job{Handler: "unknown"})
+	r.Error(err)
+}
+
+/* TODO(sio4): #road-to-v1 - define the purpose of Start clearly
+   consider to make Perform to work only when the worker is started.
+func Test_Simple_PerformBeforeStart(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	r.NoError(w.Register("sample", sampleHandler))
+
+	err := w.Perform(Job{Handler: "sample"})
+	r.Error(err)
+}
+*/
+
+func Test_Simple_PerformAfterStop(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	r.NoError(w.Register("sample", sampleHandler))
+	r.NoError(w.Start(context.Background()))
+	r.NoError(w.Stop())
+
+	err := w.Perform(Job{Handler: "sample"})
+	r.Error(err)
+}
+
+func Test_Simple_PerformAt(t *testing.T) {
 	r := require.New(t)
 
 	var hit bool
+	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+
 	wg := &sync.WaitGroup{}
 	wg.Add(1)
 
-	w := NewSimple()
 	w.Register("x", func(Args) error {
 		hit = true
 		wg.Done()
-
-		//Index out of bounds on purpose
-		println([]string{}[0])
-
 		return nil
 	})
-
-	w.Perform(Job{
+	w.PerformAt(Job{
 		Handler: "x",
-	})
+	}, time.Now().Add(5*time.Millisecond))
+
+	// how long does the handler take for assignment? hmm,
+	time.Sleep(100 * time.Millisecond)
 	wg.Wait()
 	r.True(hit)
+
+	r.NoError(w.Stop())
 }
 
 func Test_Simple_PerformIn(t *testing.T) {
 	r := require.New(t)
 
 	var hit bool
+	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+
 	wg := &sync.WaitGroup{}
 	wg.Add(1)
-	w := NewSimple()
+
 	w.Register("x", func(Args) error {
 		hit = true
 		wg.Done()
@@ -86,14 +199,61 @@ func Test_Simple_PerformIn(t *testing.T) {
 	w.PerformIn(Job{
 		Handler: "x",
 	}, 5*time.Millisecond)
+
+	// how long does the handler take for assignment? hmm,
+	time.Sleep(100 * time.Millisecond)
 	wg.Wait()
 	r.True(hit)
+
+	r.NoError(w.Stop())
 }
 
-func Test_Simple_NoHandler(t *testing.T) {
+/* TODO(sio4): #road-to-v1 - define the purpose of Start clearly
+   consider to make Perform to work only when the worker is started.
+func Test_Simple_PerformInBeforeStart(t *testing.T) {
 	r := require.New(t)
 
 	w := NewSimple()
-	err := w.Perform(Job{})
+	r.NoError(w.Register("sample", sampleHandler))
+
+	err := w.PerformIn(Job{Handler: "sample"}, 5*time.Millisecond)
+	r.Error(err)
+}
+*/
+
+func Test_Simple_PerformInAfterStop(t *testing.T) {
+	r := require.New(t)
+
+	w := NewSimple()
+	r.NoError(w.Register("sample", sampleHandler))
+	r.NoError(w.Start(context.Background()))
+	r.NoError(w.Stop())
+
+	err := w.PerformIn(Job{Handler: "sample"}, 5*time.Millisecond)
 	r.Error(err)
 }
+
+/* TODO(sio4): #road-to-v1 - it should be guaranteed to be performed
+   consider to make PerformIn to guarantee the job execution
+func Test_Simple_PerformInFollowedByStop(t *testing.T) {
+	r := require.New(t)
+
+	var hit bool
+	w := NewSimple()
+	r.NoError(w.Start(context.Background()))
+
+	w.Register("x", func(Args) error {
+		hit = true
+		return nil
+	})
+	err := w.PerformIn(Job{
+		Handler: "x",
+	}, 5*time.Millisecond)
+	r.NoError(err)
+
+	// stop the worker immediately after PerformIn
+	r.NoError(w.Stop())
+
+	r.True(hit)
+}
+*/