diff --git a/test/features/composer/data/html_analyzer_test.dart b/test/features/composer/data/html_analyzer_test.dart
new file mode 100644
index 000000000..9be54d1db
--- /dev/null
+++ b/test/features/composer/data/html_analyzer_test.dart
@@ -0,0 +1,288 @@
+import 'package:core/presentation/utils/html_transformer/html_transform.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:html/parser.dart';
+import 'package:http_parser/http_parser.dart' show MediaType;
+import 'package:jmap_dart_client/jmap/core/id.dart' show Id;
+import 'package:model/email/attachment.dart';
+import 'package:mockito/annotations.dart';
+import 'package:mockito/mockito.dart';
+import 'package:tmail_ui_user/features/email/data/local/html_analyzer.dart';
+import 'package:tmail_ui_user/features/upload/data/network/file_uploader.dart';
+import 'package:uuid/uuid.dart';
+import 'html_analyzer_test.mocks.dart';
+
+@GenerateMocks([HtmlTransform, FileUploader, Uuid])
+void main() {
+  group('HtmlAnalyzer::replaceImageBase64ToImageCID::', () {
+    late HtmlAnalyzer htmlAnalyzer;
+    late MockHtmlTransform mockHtmlTransform;
+    late MockFileUploader mockFileUploader;
+    late MockUuid mockUuid;
+
+    setUp(() {
+      mockHtmlTransform = MockHtmlTransform();
+      mockFileUploader = MockFileUploader();
+      mockUuid = MockUuid();
+      htmlAnalyzer = HtmlAnalyzer(mockHtmlTransform, mockFileUploader, mockUuid);
+    });
+
+    test(
+      'When HTML content has no base64 images,\n'
+      'should return original content and empty attachments if no inline attachments exist',
+    () async {
+      const htmlContent = '<div>Hello World</div>';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      expect(result.value1, htmlContent);
+      expect(result.value2, isEmpty);
+    });
+
+    test(
+      'When HTML content has an image with existing CID,\n'
+      'should update src to CID format and include attachment in result',
+    () async {
+      const htmlContent = '<img id="cid:test123" src="data:image/png;base64,iVBORw0KGgo=">';
+      final inlineAttachments = {
+        'test123': Attachment(
+          blobId: Id('test123'),
+          type: MediaType('image', 'png'),
+          disposition: ContentDisposition.inline,
+          cid: 'test123',
+        )
+      };
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTag = document.querySelector('img');
+      expect(imgTag?.attributes['src'], 'cid:test123');
+      expect(imgTag?.attributes.containsKey('id'), isFalse);
+      expect(result.value2.length, 1);
+      expect(result.value2.first.cid, 'test123');
+    });
+
+    test(
+      'When HTML content has a base64 image and upload succeeds,\n'
+      'should replace src with new CID and add attachment to result',
+    () async {
+      const base64Data = 'iVBORw0KGgo=';
+      const htmlContent = '<img src="data:image/png;base64,$base64Data">';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenReturn('new-uuid-123');
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenAnswer((_) async => Attachment(
+          blobId: Id('blob123'),
+          type: MediaType('image', 'png'),
+          disposition: ContentDisposition.inline,
+        ));
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTag = document.querySelector('img');
+      expect(imgTag?.attributes['src'], 'cid:new-uuid-123');
+      expect(result.value2.length, 1);
+      expect(result.value2.first.cid, 'new-uuid-123');
+      verify(mockFileUploader.uploadAttachment(any, any, uploadUri)).called(1);
+    });
+
+    test(
+      'When upload URI is null and HTML has base64 images,\n'
+      'should keep original src and not attempt uploads',
+    () async {
+      const htmlContent = '<img src="data:image/png;base64,iVBORw0KGgo=">';
+      final inlineAttachments = <String, Attachment>{};
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: null,
+      );
+
+      expect(result.value1, htmlContent);
+      expect(result.value2, isEmpty);
+      verifyNever(mockFileUploader.uploadAttachment(any, any, any));
+    });
+
+    test(
+      'When processing multiple base64 images,\n'
+      'should replace each with a unique CID and add corresponding attachments',
+    () async {
+      const htmlContent = '''
+        <img src="data:image/png;base64,iVBORw0KGgo=">
+        <img src="data:image/jpeg;base64,/9j/4AAQSkZJRg==">
+      ''';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenAnswer((_) => 'uuid1');
+
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenAnswer((_) async => Attachment(
+          blobId: Id('blob123'),
+          type: MediaType('image', 'png'),
+          disposition: ContentDisposition.inline,
+        ));
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTags = document.querySelectorAll('img');
+      expect(imgTags.length, 2);
+      expect(imgTags[0].attributes['src'], 'cid:uuid1');
+      expect(imgTags[1].attributes['src'], 'cid:uuid1');
+      expect(result.value2.length, 2);
+      verify(mockFileUploader.uploadAttachment(any, any, uploadUri)).called(2);
+    });
+
+    test(
+      'When one image upload throws an exception out of multiple base64 images,\n'
+      'should replace successful upload with CID and keep original src for failed one',
+    () async {
+      const htmlContent = '''
+        <img src="data:image/png;base64,iVBORw0KGgo=">
+        <img src="data:image/jpeg;base64,/9j/4AAQSkZJRg==">
+      ''';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenAnswer((_) => 'uuid1');
+
+      int uploadCallCount = 0;
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenAnswer((_) async {
+          uploadCallCount++;
+          if (uploadCallCount == 1) {
+            return Attachment(
+              blobId: Id('blob123'),
+              type: MediaType('image', 'png'),
+              disposition: ContentDisposition.inline,
+            );
+          } else {
+            throw Exception('Upload failed for second image');
+          }
+        });
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTags = document.querySelectorAll('img');
+      expect(imgTags.length, 2);
+      expect(imgTags[0].attributes['src'], 'cid:uuid1');
+      expect(imgTags[1].attributes['src'], 'data:image/jpeg;base64,/9j/4AAQSkZJRg==');
+      expect(result.value2.length, 1);
+      expect(result.value2.first.cid, 'uuid1');
+      verify(mockFileUploader.uploadAttachment(any, any, uploadUri)).called(2);
+    });
+
+    test(
+      'When all uploads throw exceptions for multiple base64 images,\n'
+      'should keep original src for all images and add no attachments',
+    () async {
+      const htmlContent = '''
+        <img src="data:image/png;base64,iVBORw0KGgo=">
+        <img src="data:image/jpeg;base64,/9j/4AAQSkZJRg==">
+      ''';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenAnswer((_) => 'uuid1');
+
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenThrow(Exception('Upload failed'));
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTags = document.querySelectorAll('img');
+      expect(imgTags.length, 2);
+      expect(imgTags[0].attributes['src'], 'data:image/png;base64,iVBORw0KGgo=');
+      expect(imgTags[1].attributes['src'], 'data:image/jpeg;base64,/9j/4AAQSkZJRg==');
+      expect(result.value2.length, 0);
+      verify(mockFileUploader.uploadAttachment(any, any, uploadUri)).called(2);
+    });
+
+    test(
+      'When processing an invalid base64 image that causes upload to throw an exception,\n'
+      'should keep the original invalid src and add no attachments',
+    () async {
+      const htmlContent = '<img src="data:image/png;base64,invalid-base64-data">';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenAnswer((_) => 'uuid1');
+
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenThrow(Exception('Invalid base64 data'));
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTags = document.querySelectorAll('img');
+      expect(imgTags.length, 1);
+      expect(imgTags[0].attributes['src'], 'data:image/png;base64,invalid-base64-data');
+      expect(result.value2.length, 0);
+    });
+
+    test(
+      'When upload throws an exception for a base64 image,\n'
+      'should keep the original src and add no attachments',
+    () async {
+      const htmlContent = '<img src="data:image/png;base64,iVBORw0KGgo=">';
+      final inlineAttachments = <String, Attachment>{};
+      final uploadUri = Uri.parse('https://example.com/upload');
+
+      when(mockUuid.v1()).thenAnswer((_) => 'uuid1');
+
+      when(mockFileUploader.uploadAttachment(any, any, any))
+        .thenThrow(Exception('Upload failed'));
+
+      final result = await htmlAnalyzer.replaceImageBase64ToImageCID(
+        emailContent: htmlContent,
+        inlineAttachments: inlineAttachments,
+        uploadUri: uploadUri,
+      );
+
+      final document = parse(result.value1);
+      final imgTags = document.querySelectorAll('img');
+      expect(imgTags.length, 1);
+      expect(imgTags[0].attributes['src'], 'data:image/png;base64,iVBORw0KGgo=');
+      expect(result.value2.length, 0);
+      verify(mockFileUploader.uploadAttachment(any, any, any)).called(1);
+    });
+  });
+}
diff --git a/test/features/composer/data/repository/composer_repository_impl_test.dart b/test/features/composer/data/repository/composer_repository_impl_test.dart
new file mode 100644
index 000000000..3a4a1e81e
--- /dev/null
+++ b/test/features/composer/data/repository/composer_repository_impl_test.dart
@@ -0,0 +1,236 @@
+import 'package:core/utils/application_manager.dart';
+import 'package:dartz/dartz.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http_parser/http_parser.dart';
+import 'package:jmap_dart_client/jmap/core/session/session.dart';
+import 'package:jmap_dart_client/jmap/core/user_name.dart';
+import 'package:jmap_dart_client/jmap/identities/identity.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email_address.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email_body_part.dart';
+import 'package:model/email/attachment.dart';
+import 'package:mockito/annotations.dart';
+import 'package:mockito/mockito.dart';
+import 'package:model/email/email_action_type.dart';
+import 'package:tmail_ui_user/features/composer/data/datasource/composer_datasource.dart';
+import 'package:tmail_ui_user/features/composer/data/repository/composer_repository_impl.dart';
+import 'package:tmail_ui_user/features/composer/presentation/model/create_email_request.dart';
+import 'package:tmail_ui_user/features/email/data/datasource/html_datasource.dart';
+import 'package:tmail_ui_user/features/upload/data/datasource/attachment_upload_datasource.dart';
+import 'package:uuid/uuid.dart';
+
+import 'composer_repository_impl_test.mocks.dart';
+
+@GenerateMocks([
+  AttachmentUploadDataSource,
+  ComposerDataSource,
+  HtmlDataSource,
+  ApplicationManager,
+  Uuid,
+  CreateEmailRequest,
+  Session,
+  Identity,
+])
+void main() {
+  group('ComposerRepositoryImpl::generateEmail::', () {
+    late ComposerRepositoryImpl repository;
+    late MockAttachmentUploadDataSource mockAttachmentUploadDataSource;
+    late MockComposerDataSource mockComposerDataSource;
+    late MockHtmlDataSource mockHtmlDataSource;
+    late MockApplicationManager mockApplicationManager;
+    late MockUuid mockUuid;
+    late MockCreateEmailRequest mockCreateEmailRequest;
+    late MockSession mockSession;
+    late MockIdentity mockIdentity;
+
+    setUp(() {
+      mockAttachmentUploadDataSource = MockAttachmentUploadDataSource();
+      mockComposerDataSource = MockComposerDataSource();
+      mockHtmlDataSource = MockHtmlDataSource();
+      mockApplicationManager = MockApplicationManager();
+      mockUuid = MockUuid();
+      mockCreateEmailRequest = MockCreateEmailRequest();
+      mockSession = MockSession();
+      mockIdentity = MockIdentity();
+
+      when(mockSession.username).thenReturn(UserName('test@example.com'));
+      when(mockIdentity.email).thenReturn('identity@example.com');
+      when(mockIdentity.name).thenReturn('Test User');
+      when(mockIdentity.replyTo).thenReturn({});
+
+      when(mockCreateEmailRequest.session).thenReturn(mockSession);
+      when(mockCreateEmailRequest.identity).thenReturn(mockIdentity);
+      when(mockCreateEmailRequest.replyToRecipients).thenReturn({});
+
+      repository = ComposerRepositoryImpl(
+        mockAttachmentUploadDataSource,
+        mockComposerDataSource,
+        mockHtmlDataSource,
+        mockApplicationManager,
+        mockUuid,
+      );
+    });
+
+    test(
+      'When the email content contains base64 images,\n'
+      'generateEmail should replace them with CIDs and return an email without base64',
+    () async {
+      // Arrange
+      const base64Image =
+          'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAACklEQVR4nGMAAQAABQABDQottAAAAABJRU5ErkJggg==';
+      const emailContentWithBase64 = '<p>Hello <img src="$base64Image" alt="test image"></p>';
+      const emailContentWithCid = '<p>Hello <img src="cid:unique-cid" alt="test image"></p>';
+      const userAgent = 'TestUserAgent';
+      const partIdValue = 'part-id-123';
+      final inlineAttachments = {
+        'unique-cid': Attachment(name: 'test.png'),
+      };
+      final attachments = [Attachment(name: 'test.png')];
+      final emailBodyParts = {
+        EmailBodyPart(partId: PartId(partIdValue), type: MediaType('image', 'png')),
+      };
+
+      when(mockCreateEmailRequest.emailContent).thenReturn(emailContentWithBase64);
+      when(mockCreateEmailRequest.inlineAttachments).thenReturn(inlineAttachments);
+      when(mockCreateEmailRequest.uploadUri).thenReturn(Uri.parse('https://example.com/upload'));
+      when(mockCreateEmailRequest.attachments).thenReturn(attachments);
+      when(mockCreateEmailRequest.toRecipients).thenReturn({});
+      when(mockCreateEmailRequest.ccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.bccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.subject).thenReturn('Test Subject');
+      when(mockCreateEmailRequest.draftsMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.outboxMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.emailActionType).thenReturn(EmailActionType.compose);
+      when(mockCreateEmailRequest.hasRequestReadReceipt).thenReturn(false);
+
+      when(mockHtmlDataSource.replaceImageBase64ToImageCID(
+        emailContent: emailContentWithBase64,
+        inlineAttachments: inlineAttachments,
+        uploadUri: Uri.parse('https://example.com/upload'),
+      )).thenAnswer((_) async => Tuple2(emailContentWithCid, emailBodyParts));
+
+      when(mockHtmlDataSource.removeCollapsedExpandedSignatureEffect(emailContent: emailContentWithCid))
+          .thenAnswer((_) async => emailContentWithCid);
+
+      when(mockApplicationManager.generateApplicationUserAgent())
+          .thenAnswer((_) async => userAgent);
+
+      when(mockUuid.v1()).thenReturn(partIdValue);
+
+      // Act
+      final result = await repository.generateEmail(mockCreateEmailRequest);
+
+      // Assert
+      expect(result, isA<Email>());
+      expect(result.from, {EmailAddress('Test User', 'identity@example.com')});
+      expect(result.bodyValues![PartId(partIdValue)]!.value, emailContentWithCid);
+      expect(result.attachments, containsAll(emailBodyParts));
+      expect(emailContentWithCid.contains('data:image'), isFalse);
+      verify(mockHtmlDataSource.replaceImageBase64ToImageCID(
+        emailContent: emailContentWithBase64,
+        inlineAttachments: inlineAttachments,
+        uploadUri: Uri.parse('https://example.com/upload'),
+      )).called(1);
+    });
+
+    test(
+      'When replacing base64 with CID fails,\n'
+      'generateEmail should still successfully create an email with the original content',
+    () async {
+      // Arrange
+      const emailContentWithBase64 = '<p>Hello <img src="data:image/png;base64,abc123" alt="test"></p>';
+      const userAgent = 'TestUserAgent';
+      const partIdValue = 'part-id-123';
+      final inlineAttachments = {
+        'cid-1': Attachment(name: 'test.png'),
+      };
+      final attachments = [Attachment(name: 'test.png')];
+
+      when(mockCreateEmailRequest.emailContent).thenReturn(emailContentWithBase64);
+      when(mockCreateEmailRequest.inlineAttachments).thenReturn(inlineAttachments);
+      when(mockCreateEmailRequest.uploadUri).thenReturn(Uri.parse('https://example.com/upload'));
+      when(mockCreateEmailRequest.attachments).thenReturn(attachments);
+      when(mockCreateEmailRequest.toRecipients).thenReturn({});
+      when(mockCreateEmailRequest.ccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.bccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.subject).thenReturn('Test Subject');
+      when(mockCreateEmailRequest.draftsMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.outboxMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.emailActionType).thenReturn(EmailActionType.compose);
+      when(mockCreateEmailRequest.hasRequestReadReceipt).thenReturn(false);
+
+      when(mockHtmlDataSource.replaceImageBase64ToImageCID(
+        emailContent: emailContentWithBase64,
+        inlineAttachments: inlineAttachments,
+        uploadUri: Uri.parse('https://example.com/upload'),
+      )).thenThrow(Exception('Failed to replace base64'));
+
+      when(mockHtmlDataSource.removeCollapsedExpandedSignatureEffect(emailContent: emailContentWithBase64))
+          .thenAnswer((_) async => emailContentWithBase64);
+
+      when(mockApplicationManager.generateApplicationUserAgent())
+          .thenAnswer((_) async => userAgent);
+
+      when(mockUuid.v1()).thenReturn(partIdValue);
+
+      // Act
+      final result = await repository.generateEmail(mockCreateEmailRequest);
+
+      // Assert
+      expect(result, isA<Email>());
+      expect(result.bodyValues![PartId(partIdValue)]!.value, emailContentWithBase64);
+      expect(result.attachments, isNotEmpty);
+      verify(mockHtmlDataSource.replaceImageBase64ToImageCID(
+        emailContent: emailContentWithBase64,
+        inlineAttachments: inlineAttachments,
+        uploadUri: Uri.parse('https://example.com/upload'),
+      )).called(1);
+    });
+
+    test(
+      'When the email content has no base64 images,\n'
+      'generateEmail should process it correctly and return a valid email',
+    () async {
+      const plainEmailContent = '<p>Hello, this is a simple email</p>';
+      const userAgent = 'TestUserAgent';
+      const partIdValue = 'part-id-123';
+      final attachments = [Attachment(name: 'test.png')];
+      final emailBodyParts = {
+        EmailBodyPart(partId: PartId(partIdValue), type: MediaType('image', 'png')),
+      };
+
+      when(mockCreateEmailRequest.emailContent).thenReturn(plainEmailContent);
+      when(mockCreateEmailRequest.inlineAttachments).thenReturn({});
+      when(mockCreateEmailRequest.uploadUri).thenReturn(Uri.parse('https://example.com/upload'));
+      when(mockCreateEmailRequest.attachments).thenReturn(attachments);
+      when(mockCreateEmailRequest.toRecipients).thenReturn({});
+      when(mockCreateEmailRequest.ccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.bccRecipients).thenReturn(null);
+      when(mockCreateEmailRequest.subject).thenReturn('Test Subject');
+      when(mockCreateEmailRequest.draftsMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.outboxMailboxId).thenReturn(null);
+      when(mockCreateEmailRequest.emailActionType).thenReturn(EmailActionType.compose);
+      when(mockCreateEmailRequest.hasRequestReadReceipt).thenReturn(false);
+
+      when(mockHtmlDataSource.replaceImageBase64ToImageCID(
+        emailContent: plainEmailContent,
+        inlineAttachments: {},
+        uploadUri: Uri.parse('https://example.com/upload'),
+      )).thenAnswer((_) async => Tuple2(plainEmailContent, emailBodyParts));
+
+      when(mockHtmlDataSource.removeCollapsedExpandedSignatureEffect(emailContent: plainEmailContent))
+          .thenAnswer((_) async => plainEmailContent);
+
+      when(mockApplicationManager.generateApplicationUserAgent())
+          .thenAnswer((_) async => userAgent);
+
+      when(mockUuid.v1()).thenReturn(partIdValue);
+
+      final result = await repository.generateEmail(mockCreateEmailRequest);
+
+      expect(result, isA<Email>());
+      expect(result.bodyValues![PartId(partIdValue)]!.value, plainEmailContent);
+      expect(result.attachments, containsAll(emailBodyParts));
+    });
+  });
+}
\ No newline at end of file