Tight up template mailer implementation

README.md

@@ -26,7 +26,7 @@ func main() {
 	}
 
 	// Create template mailer.
-	templateMailer := MustStandardTemplateMailer(mandrillMailer, "/templates/*.tmpl")
+	templateMailer := MustNewStandardTemplateMailer(mandrillMailer, "/templates/*.tmpl")
 
 	// Configure email for sending.
 	template := &Template{

doc.go

@@ -9,7 +9,7 @@ Package mail provides an easy interface with interchangable backends.
 	}
 
 	// Create template mailer.
-	templateMailer := MustStandardTemplateMailer(mandrillMailer, "/templates/*.tmpl")
+	templateMailer := MustNewStandardTemplateMailer(mandrillMailer, "/templates/*.tmpl")
 
 	// Configure email for sending.
 	template := &Template{

mail.go

@@ -2,6 +2,7 @@ package mail
 
 import (
 	"bytes"
+	"errors"
 	"io"
 	"net/http"
 	"text/template"
@@ -88,8 +89,8 @@ func NewStandardTemplateMailer(mailer Mailer, templatePath string) (*StandardTem
 	}, nil
 }
 
-// MustStandardTemplateMailer returns a new StandardTemplateMailer mailer or panics.
-func MustStandardTemplateMailer(mailer Mailer, templatePath string) *StandardTemplateMailer {
+// MustNewStandardTemplateMailer returns a new StandardTemplateMailer mailer or panics.
+func MustNewStandardTemplateMailer(mailer Mailer, templatePath string) *StandardTemplateMailer {
 	tpl, err := NewStandardTemplateMailer(mailer, templatePath)
 	if err != nil {
 		panic(err)
@@ -100,6 +101,14 @@ func MustStandardTemplateMailer(mailer Mailer, templatePath string) *StandardTem
 
 // Send sends an email.
 func (m *StandardTemplateMailer) Send(template *Template, config *Config) error {
+	if config == nil {
+		return errors.New("config parameter is required")
+	}
+
+	if template == nil {
+		return errors.New("template parameter is required")
+	}
+
 	textBuf := &bytes.Buffer{}
 	if err := m.template.ExecuteTemplate(textBuf, template.TextPath, template.Data); err != nil {
 		return err

mail_test.go

@@ -42,18 +42,40 @@ func TestNewStandardTemplateMailer(t *testing.T) {
 	})
 }
 
-func TestMustStandardTemplateMailer(t *testing.T) {
+func TestMustNewStandardTemplateMailer(t *testing.T) {
 	mockMailer := &MockMailer{}
 
 	assert.Panics(t, func() {
-		MustStandardTemplateMailer(mockMailer, "./invalid/*.tmpl")
+		MustNewStandardTemplateMailer(mockMailer, "./invalid/*.tmpl")
 	})
 }
 
 func TestStandardTemplateMailer_Send(t *testing.T) {
+	t.Run("config is required", func(t *testing.T) {
+		mockMailer := &MockMailer{}
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+
+		template := &Template{}
+		err := templateMailer.Send(template, nil)
+
+		require.Error(t, err)
+		assert.EqualError(t, err, "config parameter is required")
+	})
+
+	t.Run("template is required", func(t *testing.T) {
+		mockMailer := &MockMailer{}
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+
+		config := &Config{}
+		err := templateMailer.Send(nil, config)
+
+		require.Error(t, err)
+		assert.EqualError(t, err, "template parameter is required")
+	})
+
 	t.Run("failed to execute plain text template", func(t *testing.T) {
 		mockMailer := &MockMailer{}
-		templateMailer := MustStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
 
 		template := &Template{
 			TextPath: "foo_txt.tmpl",
@@ -66,7 +88,7 @@ func TestStandardTemplateMailer_Send(t *testing.T) {
 
 	t.Run("failed to execute HTML template", func(t *testing.T) {
 		mockMailer := &MockMailer{}
-		templateMailer := MustStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
 
 		template := &Template{
 			TextPath: "foo_text.tmpl",
@@ -80,7 +102,7 @@ func TestStandardTemplateMailer_Send(t *testing.T) {
 
 	t.Run("failed to send email", func(t *testing.T) {
 		mockMailer := &MockMailer{}
-		templateMailer := MustStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
 
 		errUnexpected := errors.New("unexpected error")
 		mockMailer.On("Send", mock.Anything).Return(errUnexpected)
@@ -97,7 +119,7 @@ func TestStandardTemplateMailer_Send(t *testing.T) {
 
 	t.Run("success", func(t *testing.T) {
 		mockMailer := &MockMailer{}
-		templateMailer := MustStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
+		templateMailer := MustNewStandardTemplateMailer(mockMailer, "./testdata/*.tmpl")
 
 		config := &Config{
 			From: &Address{
@@ -121,6 +143,9 @@ func TestStandardTemplateMailer_Send(t *testing.T) {
 		mockMailer.On("Send", eml).Return(nil)
 
 		template := &Template{
+			Data: map[string]interface{}{
+				"FooVar": "foo",
+			},
 			TextPath: "foo_text.tmpl",
 			HTMLPath: "foo_html.tmpl",
 		}

testdata/foo_html.tmpl

@@ -1 +1 @@
-foohtml
+{{ .FooVar }}html

testdata/foo_text.tmpl

@@ -1 +1 @@
-footext
+{{ .FooVar }}text