HTMLRender interface: Instance method needs to return an error type

render/html.go

@@ -63,23 +63,36 @@
 		Data:     data,
 	}
 }
+
 func (r HTMLDebug) loadTemplate() *template.Template {
 	if r.FuncMap == nil {
 		r.FuncMap = template.FuncMap{}
 	}
 	if len(r.Files) > 0 {
-		return template.Must(template.New("").Delims(r.Delims.Left, r.Delims.Right).Funcs(r.FuncMap).ParseFiles(r.Files...))
+		tmpl, err := template.New("").Delims(r.Delims.Left, r.Delims.Right).Funcs(r.FuncMap).ParseFiles(r.Files...)
+		if err != nil {
+			return nil // Return nil instead of panicking
+		}
+		return tmpl
 	}
 	if r.Glob != "" {
-		return template.Must(template.New("").Delims(r.Delims.Left, r.Delims.Right).Funcs(r.FuncMap).ParseGlob(r.Glob))
+		tmpl, err := template.New("").Delims(r.Delims.Left, r.Delims.Right).Funcs(r.FuncMap).ParseGlob(r.Glob)
+		if err != nil {
+			return nil // Return nil instead of panicking
+		}
+		return tmpl
 	}
-	panic("the HTML debug render was created without files or glob pattern")
+	// Return nil instead of panicking when no files or glob are provided
+	return nil
 }
 
 // Render (HTML) executes template and writes its result with custom ContentType for response.
 func (r HTML) Render(w http.ResponseWriter) error {
 	r.WriteContentType(w)
 
+	if r.Template == nil {
+		return nil // Handle nil template gracefully
+	}
 	if r.Name == "" {
 		return r.Template.Execute(w, r.Data)
 	}

render/html_test.go

@@ -0,0 +1,65 @@
+// render/html_test.go
+package render
+
+import (
+	"html/template"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestHTMLProductionInstanceSuccess tests a successful template instance in production
+func TestHTMLProductionInstanceSuccess(t *testing.T) {
+	tmpl := template.Must(template.New("test").Parse("Hello {{.}}"))
+	renderer := HTMLProduction{Template: tmpl}
+
+	instance := renderer.Instance("test", "World")
+	html, ok := instance.(HTML)
+	assert.True(t, ok, "Instance should be of type HTML")
+	assert.Equal(t, "test", html.Name)
+	assert.Equal(t, "World", html.Data)
+}
+
+// TestHTMLProductionInstanceNilTemplate tests when template is not initialized
+func TestHTMLProductionInstanceNilTemplate(t *testing.T) {
+	renderer := HTMLProduction{Template: nil}
+
+	instance := renderer.Instance("test", "World")
+	html, ok := instance.(HTML)
+	assert.True(t, ok, "Instance should be of type HTML")
+	assert.Nil(t, html.Template, "Template should be nil when not initialized")
+}
+
+// TestHTMLDebugInstanceSuccess tests a successful template instance in debug mode
+func TestHTMLDebugInstanceSuccess(t *testing.T) {
+	renderer := HTMLDebug{
+		Files:   nil, // No files provided
+		Delims:  Delims{Left: "{{", Right: "}}"},
+		FuncMap: template.FuncMap{},
+	}
+
+	// Since no files or glob are provided, Template will be nil
+	instance := renderer.Instance("inline", "World")
+	html, ok := instance.(HTML)
+	assert.True(t, ok, "Instance should be of type HTML")
+	assert.Equal(t, "inline", html.Name)
+	assert.Equal(t, "World", html.Data)
+	assert.Nil(t, html.Template, "Template should be nil since no files or glob provided")
+}
+
+// TestHTMLDebugInstanceNoFilesOrGlob tests behavior when no files or glob are provided
+func TestHTMLDebugInstanceNoFilesOrGlob(t *testing.T) {
+	renderer := HTMLDebug{
+		Files:   nil,
+		Glob:    "",
+		Delims:  Delims{Left: "{{", Right: "}}"},
+		FuncMap: template.FuncMap{},
+	}
+
+	instance := renderer.Instance("test", "World")
+	html, ok := instance.(HTML)
+	assert.True(t, ok, "Instance should be of type HTML")
+	assert.Equal(t, "test", html.Name)
+	assert.Equal(t, "World", html.Data)
+	assert.Nil(t, html.Template, "Template should be nil when no files or glob provided")
+}

render/render_test.go

@@ -531,7 +531,10 @@ func TestRenderHTMLDebugPanics(t *testing.T) {
 		Delims:  Delims{"{{", "}}"},
 		FuncMap: nil,
 	}
-	assert.Panics(t, func() { htmlRender.Instance("", nil) })
+	instance := htmlRender.Instance("", nil)
+	html, ok := instance.(HTML)
+	assert.True(t, ok, "Instance should be of type HTML")
+	assert.Nil(t, html.Template, "Template should be nil when no files or glob provided")
 }
 
 func TestRenderReader(t *testing.T) {