Add tests for message attachment methods using templates

Included unit tests to verify the functionality of the AttachHTMLTemplate and AttachTextTemplate methods, ensuring valid, invalid, and nil templates are handled correctly. Also added tests for AttachFromEmbedFS to validate attachments from embedded files.

msg_test.go

@@ -7,6 +7,7 @@ package mail
 import (
 	"bytes"
 	"context"
+	"embed"
 	"errors"
 	"fmt"
 	ht "html/template"
@@ -135,10 +136,8 @@ var (
 	}
 )
 
-/*
+//go:embed testdata/attachment.txt
-//go:embed README.md
 var efs embed.FS
-*/
 
 func TestNewMsg(t *testing.T) {
 	t.Run("create new message", func(t *testing.T) {
@@ -4596,6 +4595,181 @@ func TestMsg_AttachReadSeeker(t *testing.T) {
 	})
 }
 
+func TestMsg_AttachHTMLTemplate(t *testing.T) {
+	tplString := `<p>{{.teststring}}</p>`
+	invalidTplString := `<p>{{call $.invalid .teststring}}</p>`
+	data := map[string]interface{}{"teststring": "this is a test"}
+	htmlTpl, err := ht.New("htmltpl").Parse(tplString)
+	if err != nil {
+		t.Fatalf("failed to parse HTML template: %s", err)
+	}
+	invalidTpl, err := ht.New("htmltpl").Parse(invalidTplString)
+	if err != nil {
+		t.Fatalf("failed to parse invalid HTML template: %s", err)
+	}
+	t.Run("AttachHTMLTemplate with valid template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err = message.AttachHTMLTemplate("attachment.html", htmlTpl, data); err != nil {
+			t.Fatalf("failed to set body HTML template: %s", err)
+		}
+		attachments := message.GetAttachments()
+		if len(attachments) != 1 {
+			t.Fatalf("failed to retrieve attachments list")
+		}
+		if attachments[0] == nil {
+			t.Fatal("expected attachment to be not nil")
+		}
+		if attachments[0].Name != "attachment.html" {
+			t.Errorf("expected attachment name to be %s, got: %s", "attachment.html", attachments[0].Name)
+		}
+		messageBuf := bytes.NewBuffer(nil)
+		_, err = attachments[0].Writer(messageBuf)
+		if err != nil {
+			t.Errorf("writer func failed: %s", err)
+		}
+		got := strings.TrimSpace(messageBuf.String())
+		if !strings.EqualFold(got, "<p>this is a test</p>") {
+			t.Errorf("expected message body to be %s, got: %s", "<p>this is a test</p>", got)
+		}
+	})
+	t.Run("AttachHTMLTemplate with invalid template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		err = message.AttachHTMLTemplate("attachment.html", invalidTpl, data)
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		expectErr := `failed to attach template: failed to execute template: template: htmltpl:1:5: executing "htmltpl" ` +
+			`at <call $.invalid .teststring>: error calling call: call of nil`
+		if !strings.EqualFold(err.Error(), expectErr) {
+			t.Errorf("expected error to be %s, got: %s", expectErr, err.Error())
+		}
+	})
+	t.Run("AttachHTMLTemplate with nil template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		err = message.AttachHTMLTemplate("attachment.html", nil, data)
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		expectedErr := `failed to attach template: ` + errTplPointerNil
+		if !strings.EqualFold(err.Error(), expectedErr) {
+			t.Errorf("expected error to be %s, got: %s", expectedErr, err.Error())
+		}
+	})
+}
+
+func TestMsg_AttachTextTemplate(t *testing.T) {
+	tplString := `Teststring: {{.teststring}}`
+	invalidTplString := `Teststring: {{call $.invalid .teststring}}`
+	data := map[string]interface{}{"teststring": "this is a test"}
+	textTpl, err := ttpl.New("texttpl").Parse(tplString)
+	if err != nil {
+		t.Fatalf("failed to parse Text template: %s", err)
+	}
+	invalidTpl, err := ttpl.New("texttpl").Parse(invalidTplString)
+	if err != nil {
+		t.Fatalf("failed to parse invalid Text template: %s", err)
+	}
+	t.Run("AttachTextTemplate with valid template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err = message.AttachTextTemplate("attachment.txt", textTpl, data); err != nil {
+			t.Fatalf("failed to set body HTML template: %s", err)
+		}
+		attachments := message.GetAttachments()
+		if len(attachments) != 1 {
+			t.Fatalf("failed to retrieve attachments list")
+		}
+		if attachments[0] == nil {
+			t.Fatal("expected attachment to be not nil")
+		}
+		if attachments[0].Name != "attachment.txt" {
+			t.Errorf("expected attachment name to be %s, got: %s", "attachment.txt", attachments[0].Name)
+		}
+		messageBuf := bytes.NewBuffer(nil)
+		_, err = attachments[0].Writer(messageBuf)
+		if err != nil {
+			t.Errorf("writer func failed: %s", err)
+		}
+		got := strings.TrimSpace(messageBuf.String())
+		if !strings.EqualFold(got, "Teststring: this is a test") {
+			t.Errorf("expected message body to be %s, got: %s", "Teststring: this is a test", got)
+		}
+	})
+	t.Run("AttachTextTemplate with invalid template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		err = message.AttachTextTemplate("attachment.txt", invalidTpl, data)
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		expectErr := `failed to attach template: failed to execute template: template: texttpl:1:14: executing "texttpl" ` +
+			`at <call $.invalid .teststring>: error calling call: call of nil`
+		if !strings.EqualFold(err.Error(), expectErr) {
+			t.Errorf("expected error to be %s, got: %s", expectErr, err.Error())
+		}
+	})
+	t.Run("AttachTextTemplate with nil template", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		err = message.AttachTextTemplate("attachment.html", nil, data)
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		expectedErr := `failed to attach template: ` + errTplPointerNil
+		if !strings.EqualFold(err.Error(), expectedErr) {
+			t.Errorf("expected error to be %s, got: %s", expectedErr, err.Error())
+		}
+	})
+}
+
+func TestMsg_AttachFromEmbedFS(t *testing.T) {
+	t.Run("AttachFromEmbedFS successful", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.AttachFromEmbedFS("testdata/attachment.txt", &efs,
+			WithFileName("attachment.txt")); err != nil {
+			t.Fatalf("failed to attach from embed FS: %s", err)
+		}
+		attachments := message.GetAttachments()
+		if len(attachments) != 1 {
+			t.Fatalf("failed to retrieve attachments list")
+		}
+		if attachments[0] == nil {
+			t.Fatal("expected attachment to be not nil")
+		}
+		if attachments[0].Name != "attachment.txt" {
+			t.Errorf("expected attachment name to be %s, got: %s", "attachment.txt", attachments[0].Name)
+		}
+		messageBuf := bytes.NewBuffer(nil)
+		_, err := attachments[0].Writer(messageBuf)
+		if err != nil {
+			t.Errorf("writer func failed: %s", err)
+		}
+		got := strings.TrimSpace(messageBuf.String())
+		if !strings.EqualFold(got, "This is a test attachment") {
+			t.Errorf("expected message body to be %s, got: %s", "This is a test attachment", got)
+		}
+
+	})
+}
+
 /*
 // TestNewMsgWithMiddleware tests WithMiddleware