Add tests for GetAttachments method in Msg

This commit introduces unit tests for the GetAttachments method in the Msg struct to ensure it correctly handles both single and multiple attachments. The tests verify the name and content of the attachments to validate the expected behavior.

msg_test.go

@@ -3207,6 +3207,77 @@ func TestMsg_GetParts(t *testing.T) {
 	})
 }
 
+func TestMsg_GetAttachments(t *testing.T) {
+	t.Run("GetAttachments with single attachment", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		message.AttachFile("testdata/attachment.txt")
+		attachments := message.GetAttachments()
+		if len(attachments) != 1 {
+			t.Fatalf("GetAttachments: expected 1 attachment, got: %d", len(attachments))
+		}
+		if attachments[0] == nil {
+			t.Fatalf("GetAttachments: expected attachment, got nil")
+		}
+		if attachments[0].Name != "attachment.txt" {
+			t.Errorf("GetAttachments: 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("GetAttachments: Writer func failed: %s", err)
+		}
+		if !strings.EqualFold(messageBuf.String(), "This is a test attachment\n") {
+			t.Errorf("GetParts: expected message body to be %s, got: %s", "This is a test attachment\n",
+				messageBuf.String())
+		}
+	})
+	t.Run("GetAttachments with multiple attachments", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		message.AttachFile("testdata/attachment.txt")
+		message.AttachFile("testdata/attachment.txt", WithFileName("attachment2.txt"))
+		attachments := message.GetAttachments()
+		if len(attachments) != 2 {
+			t.Fatalf("GetAttachments: expected 2 attachment, got: %d", len(attachments))
+		}
+		if attachments[0] == nil || attachments[1] == nil {
+			t.Fatalf("GetAttachments: expected attachment, got nil")
+		}
+		if attachments[0].Name != "attachment.txt" {
+			t.Errorf("GetAttachments: expected attachment name to be %s, got: %s", "attachment.txt",
+				attachments[0].Name)
+		}
+		if attachments[1].Name != "attachment2.txt" {
+			t.Errorf("GetAttachments: expected attachment name to be %s, got: %s", "attachment2.txt",
+				attachments[1].Name)
+		}
+		messageBuf := bytes.NewBuffer(nil)
+		_, err := attachments[0].Writer(messageBuf)
+		if err != nil {
+			t.Errorf("GetAttachments: Writer func failed: %s", err)
+		}
+		if !strings.EqualFold(messageBuf.String(), "This is a test attachment\n") {
+			t.Errorf("GetParts: expected message body to be %s, got: %s", "This is a test attachment\n",
+				messageBuf.String())
+		}
+		messageBuf.Reset()
+		_, err = attachments[1].Writer(messageBuf)
+		if err != nil {
+			t.Errorf("GetAttachments: Writer func failed: %s", err)
+		}
+		if !strings.EqualFold(messageBuf.String(), "This is a test attachment\n") {
+			t.Errorf("GetParts: expected message body to be %s, got: %s", "This is a test attachment\n",
+				messageBuf.String())
+		}
+	})
+}
+
 // checkAddrHeader verifies the correctness of an AddrHeader in a Msg based on the provided criteria.
 // It checks whether the AddrHeader contains the correct address, name, and number of fields.
 func checkAddrHeader(t *testing.T, message *Msg, header AddrHeader, fn string, field, wantFields int,