avoid panic if template was added twice

core/template.go

@@ -11,23 +11,29 @@ import (
 type Renderer struct {
 	multitemplate.Renderer
 	TemplatesBox *packr.Box
-	FuncMap template.FuncMap
+	FuncMap      template.FuncMap
+	alreadyAdded map[string]*template.Template
 }
 
 // NewRenderer is a Renderer constructor
 func NewRenderer(funcMap template.FuncMap) Renderer {
 	return Renderer{
-		Renderer: multitemplate.NewRenderer(),
+		Renderer:     multitemplate.NewRenderer(),
-		FuncMap:  funcMap,
+		FuncMap:      funcMap,
+		alreadyAdded: map[string]*template.Template{},
 	}
 }
 
 // Push is an AddFromFilesFuncs wrapper
 func (r *Renderer) Push(name string, files ...string) *template.Template {
+	if tpl := r.getTemplate(name); tpl != nil {
+		return tpl
+	}
+
 	if r.TemplatesBox == nil {
-		return r.AddFromFilesFuncs(name, r.FuncMap, files...)
+		return r.storeTemplate(name, r.AddFromFilesFuncs(name, r.FuncMap, files...))
 	} else {
-		return r.addFromBox(name, r.FuncMap, files...)
+		return r.storeTemplate(name, r.addFromBox(name, r.FuncMap, files...))
 	}
 }
 
@@ -42,4 +48,32 @@ func (r *Renderer) addFromBox(name string, funcMap template.FuncMap, files ...st
 	}
 
 	return r.AddFromStringsFuncs(name, funcMap, filesData...)
-}
+}
+
+// storeTemplate stores built template if multitemplate.DynamicRender is used.
+// Dynamic render doesn't store templates - it stores builders, that's why we can't just extract them.
+// It possibly can cause data inconsistency in developer enviroments where return value from Renderer.Push is used.
+func (r *Renderer) storeTemplate(name string, tpl *template.Template) *template.Template {
+	if _, ok := r.Renderer.(multitemplate.DynamicRender); ok {
+		r.alreadyAdded[name] = tpl
+	}
+
+	return tpl
+}
+
+// getTemplate returns template from render or from storage
+func (r *Renderer) getTemplate(name string) *template.Template {
+	if renderer, ok := r.Renderer.(multitemplate.Render); ok {
+		if i, ok := renderer[name]; ok {
+			return i
+		}
+	}
+
+	if _, ok := r.Renderer.(multitemplate.DynamicRender); ok {
+		if i, ok := r.alreadyAdded[name]; ok {
+			return i
+		}
+	}
+
+	return nil
+}

core/template_test.go

@@ -24,6 +24,11 @@ type TemplateTest struct {
 }
 
 func (t *TemplateTest) SetupSuite() {
+	t.initTestData()
+	t.renderer = t.initRenderer()
+}
+
+func (t *TemplateTest) initTestData() {
 	if _, err := os.Stat(testTemplatesDir); err != nil && os.IsNotExist(err) {
 		err := os.Mkdir(testTemplatesDir, os.ModePerm)
 		require.Nil(t.T(), err)
@@ -34,8 +39,10 @@ func (t *TemplateTest) SetupSuite() {
 		require.Nil(t.T(), err1)
 		require.Nil(t.T(), err2)
 	}
+}
 
-	t.renderer = NewRenderer(template.FuncMap{
+func (t *TemplateTest) initRenderer() Renderer {
+	return NewRenderer(template.FuncMap{
 		"trans": func(data string) string {
 			if data == "test" {
 				return "ok"
@@ -51,6 +58,25 @@ func (t *TemplateTest) Test_Push() {
 	assert.Equal(t.T(), 3, len(tpl.Templates()))
 }
 
+func (t *TemplateTest) Test_PushAlreadyExists() {
+	defer func() {
+		assert.Nil(t.T(), recover())
+	}()
+
+	tpl := t.renderer.Push("index", fmt.Sprintf(testTemplatesFile, 1), fmt.Sprintf(testTemplatesFile, 2))
+	assert.Equal(t.T(), 3, len(tpl.Templates()))
+}
+
+func (t *TemplateTest) Test_PushNewInstance() {
+	defer func() {
+		assert.Nil(t.T(), recover())
+	}()
+
+	newInstance := t.initRenderer()
+	tpl := newInstance.Push("index", fmt.Sprintf(testTemplatesFile, 1), fmt.Sprintf(testTemplatesFile, 2))
+	assert.Equal(t.T(), 3, len(tpl.Templates()))
+}
+
 func TestTemplate_Suite(t *testing.T) {
 	suite.Run(t, new(TemplateTest))
 }