Improve httpapp

Author: RussellLuo

pkg/appx/httpapp/value.go

@@ -13,8 +13,17 @@ type Value struct {
 	Router  chi.Router  // The HTTP router.
 }
 
-func MustGetService(value interface{}) interface{} {
-	return value.(*Value).Service
+func GetService(value interface{}) (interface{}, error) {
+	val, ok := value.(*Value)
+	if !ok {
+		return nil, fmt.Errorf("value %#v cannot be converted to *httpapp.Value", value)
+	}
+
+	if val == nil || val.Service == nil {
+		return nil, fmt.Errorf("value %#v holds no service", val)
+	}
+
+	return val.Service, nil
 }
 
 func GetRouter(value interface{}) (chi.Router, error) {
@@ -57,5 +66,15 @@ func R(ctx appx.Context) *RequiredServiceGetter {
 }
 
 func (g *RequiredServiceGetter) MustGet(name string) interface{} {
-	return MustGetService(g.ctx.Required[name].Value)
+	app, ok := g.ctx.Required[name]
+	if !ok {
+		panic(fmt.Errorf("app %q is not a required application", name))
+	}
+
+	svc, err := GetService(app.Value)
+	if err != nil {
+		panic(err)
+	}
+
+	return svc
 }

pkg/appx/httpapp/value_test.go

@@ -0,0 +1,87 @@
+package httpapp
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/go-chi/chi"
+)
+
+func TestGetService(t *testing.T) {
+	svc := struct{}{}
+	cases := []struct {
+		in      interface{}
+		wantSvc interface{}
+		wantErr error
+	}{
+		{
+			in:      nil,
+			wantSvc: nil,
+			wantErr: errors.New("value <nil> cannot be converted to *httpapp.Value"),
+		},
+		{
+			in:      (*Value)(nil),
+			wantSvc: nil,
+			wantErr: errors.New("value (*httpapp.Value)(nil) holds no service"),
+		},
+		{
+			in:      &Value{},
+			wantSvc: nil,
+			wantErr: errors.New("value &httpapp.Value{Service:interface {}(nil), Router:chi.Router(nil)} holds no service"),
+		},
+		{
+			in:      &Value{Service: svc},
+			wantSvc: svc,
+			wantErr: nil,
+		},
+	}
+	for _, c := range cases {
+		svc, err := GetService(c.in)
+		if svc != c.wantSvc {
+			t.Fatalf("Service: got (%#v), want (%#v)", svc, c.wantSvc)
+		}
+		if !reflect.DeepEqual(err, c.wantErr) {
+			t.Fatalf("Error: got (%#v), want (%#v)", err, c.wantErr)
+		}
+	}
+}
+
+func TestGetRouter(t *testing.T) {
+	router := chi.NewRouter()
+	cases := []struct {
+		in         interface{}
+		wantRouter interface{}
+		wantErr    error
+	}{
+		{
+			in:         nil,
+			wantRouter: nil,
+			wantErr:    errors.New("value <nil> cannot be converted to *httpapp.Value"),
+		},
+		{
+			in:         (*Value)(nil),
+			wantRouter: nil,
+			wantErr:    errors.New("value (*httpapp.Value)(nil) is not routable"),
+		},
+		{
+			in:         &Value{},
+			wantRouter: nil,
+			wantErr:    errors.New("value &httpapp.Value{Service:interface {}(nil), Router:chi.Router(nil)} is not routable"),
+		},
+		{
+			in:         &Value{Router: router},
+			wantRouter: router,
+			wantErr:    nil,
+		},
+	}
+	for _, c := range cases {
+		router, err := GetRouter(c.in)
+		if router != c.wantRouter {
+			t.Fatalf("Router: got (%#v), want (%#v)", router, c.wantRouter)
+		}
+		if !reflect.DeepEqual(err, c.wantErr) {
+			t.Fatalf("Error: got (%#v), want (%#v)", err, c.wantErr)
+		}
+	}
+}