♻️(email) adapt email when no title

Default title is not set when we create a document
anymore. We need to adapt the email to handle
this case.

src/backend/core/models.py

@@ -697,6 +697,7 @@ class Document(MP_Node, BaseModel):
                 "document": self,
                 "domain": domain,
                 "link": f"{domain}/docs/{self.id}/",
+                "document_title": self.title or str(_("Untitled Document")),
                 "logo_img": settings.EMAIL_LOGO_IMG,
             }
         )
@@ -738,8 +739,12 @@ class Document(MP_Node, BaseModel):
                     '{name} invited you with the role "{role}" on the following document:'
                 ).format(name=sender_name_email, role=role.lower()),
             }
-            subject = _("{name} shared a document with you: {title}").format(
-                name=sender_name, title=self.title
+            subject = (
+                context["title"]
+                if not self.title
+                else _("{name} shared a document with you: {title}").format(
+                    name=sender_name, title=self.title
+                )
             )
 
         self.send_email(subject, [email], context, language)

src/backend/core/tests/test_models_documents.py

@@ -636,6 +636,37 @@ def test_models_documents__email_invitation__success():
     assert f"docs/{document.id}/" in email_content
 
 
+def test_models_documents__email_invitation__success_empty_title():
+    """
+    The email invitation is sent successfully.
+    """
+    document = factories.DocumentFactory(title=None)
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 0
+
+    sender = factories.UserFactory(full_name="Test Sender", email="sender@example.com")
+    document.send_invitation_email(
+        "guest@example.com", models.RoleChoices.EDITOR, sender, "en"
+    )
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 1
+
+    # pylint: disable-next=no-member
+    email = mail.outbox[0]
+
+    assert email.to == ["guest@example.com"]
+    email_content = " ".join(email.body.split())
+
+    assert "Test sender shared a document with you!" in email.subject
+    assert (
+        "Test Sender (sender@example.com) invited you with the role "editor" "
+        "on the following document: Untitled Document" in email_content
+    )
+    assert f"docs/{document.id}/" in email_content
+
+
 def test_models_documents__email_invitation__success_fr():
     """
     The email invitation is sent successfully in french.

src/mail/mjml/invitation.mjml

@@ -22,7 +22,7 @@
           <!-- Main Message -->
           <mj-text>
             {{message|capfirst}}
-            <a href="{{link}}">{{document.title}}</a>
+            <a href="{{link}}">{{document_title}}</a>
           </mj-text>
           <mj-button
             href="{{link}}"