make Mailer an interface

email/mockMailer.go

@@ -1,13 +1,28 @@
 package email
 
+import "log"
+
 // MockMailer is a mock Mailer
 type MockMailer struct {
-	LoginTokenFn      func(name, email string, c ContentLoginToken) error
-	LoginTokenInvoked bool
+	SendFn      func(m Message) error
+	SendInvoked bool
 }
 
-// LoginToken is a mock for LoginToken
-func (s *MockMailer) LoginToken(n, e string, c ContentLoginToken) error {
-	s.LoginTokenInvoked = true
-	return s.LoginTokenFn(n, e, c)
+func logMessage(m Message) {
+	log.Printf("MockMailer email sent:\nSubject: %s\nTo: %s <%s>\nContext: %#v\n", m.Subject, m.To.Name, m.To.Address, m.Content)
+}
+
+func NewMockMailer() *MockMailer {
+	log.Println("ATTENTION: SMTP Mailer not configured => printing emails to stdout")
+	return &MockMailer{
+		SendFn: func(m Message) error {
+			logMessage(m)
+			return nil
+		},
+	}
+}
+
+func (s *MockMailer) Send(m Message) error {
+	s.SendInvoked = true
+	return s.SendFn(m)
 }