✨(backend) manage reconciliation requests for user accounts (#1878)

For now, the reconciliation requests are imported through CSV in the
Django admin, which sends confirmation email to both addresses. When
both are checked, the actual reconciliation is processed, and all
user-related content is updated.

## Purpose

Fix #1616 // Replaces #1708

For now, the reconciliation requests are imported through CSV in the
Django admin, which sends confirmation email to both addresses. When
both are checked, the actual reconciliation is processed, and all
user-related content is updated.


## Proposal
- [x] New `UserReconciliationCsvImport` model to manage the import of
reconciliation requests through a task
(`user_reconciliation_csv_import_job`)
- [x] New `UserReconciliation` model to store the user reconciliation
requests themselves (a row = a `active_user`/`inactive_user` pair)
  - [x] On save, a confirmation email is sent to the users
- [x] A `process_reconciliation` admin action process the action on the
requested entries, if both emails have been checked.
- [x] Bulk update the `DocumentAccess` items, while managing the case
where both users have access to the document (keeping the higher role)
- [x] Bulk update the `LinkTrace` items, while managing the case where
both users have link traces to the document
- [x] Bulk update the `DocumentFavorite` items, while managing the case
where both users have put the document in their favorites
- [x] Bulk update the comment system items (`Thread`, `Comment` and
`Reaction` items)
  - [x] Bulk update the `is_active` status on both users
- [x] New `USER_RECONCILIATION_FORM_URL` env variable for the "make a
new request" URL in an email.
- [x] Write unit tests
- [x] Remove the unused `email_user()` method on `User`, replaced with
`send_email()` similar to the one on the `Document` model


## Demo page reconciliation success

<img width="1149" height="746" alt="image"
src="https://github.com/user-attachments/assets/09ba2b38-7af3-41fa-a64f-ce3c4fd8548d"
/>

---------

Co-authored-by: Anthony LC <anthony.le-courric@mail.numerique.gouv.fr>

src/backend/core/tests/data/example_reconciliation_basic.csv

@@ -0,0 +1,6 @@
+active_email,inactive_email,active_email_checked,inactive_email_checked,status,id
+"user.test40@example.com","user.test41@example.com",0,0,pending,1
+"user.test42@example.com","user.test43@example.com",0,1,pending,2
+"user.test44@example.com","user.test45@example.com",1,0,pending,3
+"user.test46@example.com","user.test47@example.com",1,1,pending,4
+"user.test48@example.com","user.test49@example.com",1,1,pending,5

src/backend/core/tests/data/example_reconciliation_error.csv

@@ -0,0 +1,2 @@
+active_email,inactive_email,active_email_checked,inactive_email_checked,status,id
+"user.test40@example.com",,0,0,pending,40

src/backend/core/tests/data/example_reconciliation_grist_form.csv

@@ -0,0 +1,5 @@
+merge_accept,active_email,inactive_email,status,id
+true,user.test10@example.com,user.test11@example.com|user.test12@example.com,pending,10
+true,user.test30@example.com,user.test31@example.com|user.test32@example.com|user.test33@example.com|user.test34@example.com|user.test35@example.com,pending,11
+true,user.test20@example.com,user.test21@example.com,pending,12
+true,user.test22@example.com,user.test23@example.com,pending,13

src/backend/core/tests/data/example_reconciliation_grist_form_error.csv

@@ -0,0 +1,2 @@
+merge_accept,active_email,inactive_email,status,id
+true,user.test20@example.com,user.test20@example.com,pending,20

src/backend/core/tests/data/example_reconciliation_missing_column.csv

@@ -0,0 +1,6 @@
+active_email,inactive_email,active_email_checked,inactive_email_checked,status
+"user.test40@example.com","user.test41@example.com",0,0,pending
+"user.test42@example.com","user.test43@example.com",0,1,pending
+"user.test44@example.com","user.test45@example.com",1,0,pending
+"user.test46@example.com","user.test47@example.com",1,1,pending
+"user.test48@example.com","user.test49@example.com",1,1,pending

src/backend/core/tests/test_api_user_reconciliation.py

@@ -0,0 +1,85 @@
+"""
+Unit tests for the ReconciliationConfirmView API view.
+"""
+
+import uuid
+
+from django.conf import settings
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories, models
+
+pytestmark = pytest.mark.django_db
+
+
+def test_reconciliation_confirm_view_sets_active_checked():
+    """GETting the active confirmation endpoint should set active_email_checked."""
+    user = factories.UserFactory(email="user.confirm1@example.com")
+    other = factories.UserFactory(email="user.confirm2@example.com")
+    rec = models.UserReconciliation.objects.create(
+        active_email=user.email,
+        inactive_email=other.email,
+        active_user=user,
+        inactive_user=other,
+        active_email_checked=False,
+        inactive_email_checked=False,
+        status="ready",
+    )
+
+    client = APIClient()
+    conf_id = rec.active_email_confirmation_id
+    url = f"/api/{settings.API_VERSION}/user-reconciliations/active/{conf_id}/"
+    resp = client.get(url)
+    assert resp.status_code == 200
+    assert resp.json() == {"detail": "Confirmation received"}
+
+    rec.refresh_from_db()
+    assert rec.active_email_checked is True
+
+
+def test_reconciliation_confirm_view_sets_inactive_checked():
+    """GETting the inactive confirmation endpoint should set inactive_email_checked."""
+    user = factories.UserFactory(email="user.confirm3@example.com")
+    other = factories.UserFactory(email="user.confirm4@example.com")
+    rec = models.UserReconciliation.objects.create(
+        active_email=user.email,
+        inactive_email=other.email,
+        active_user=user,
+        inactive_user=other,
+        active_email_checked=False,
+        inactive_email_checked=False,
+        status="ready",
+    )
+
+    client = APIClient()
+    conf_id = rec.inactive_email_confirmation_id
+    url = f"/api/{settings.API_VERSION}/user-reconciliations/inactive/{conf_id}/"
+    resp = client.get(url)
+    assert resp.status_code == 200
+    assert resp.json() == {"detail": "Confirmation received"}
+
+    rec.refresh_from_db()
+    assert rec.inactive_email_checked is True
+
+
+def test_reconciliation_confirm_view_invalid_user_type_returns_400():
+    """GETting with an invalid user_type should return 400."""
+    client = APIClient()
+    # Use a valid uuid format but invalid user_type
+
+    url = f"/api/{settings.API_VERSION}/user-reconciliations/other/{uuid.uuid4()}/"
+    resp = client.get(url)
+    assert resp.status_code == 400
+    assert resp.json() == {"detail": "Invalid user_type"}
+
+
+def test_reconciliation_confirm_view_not_found_returns_404():
+    """GETting with a non-existing confirmation_id should return 404."""
+    client = APIClient()
+
+    url = f"/api/{settings.API_VERSION}/user-reconciliations/active/{uuid.uuid4()}/"
+    resp = client.get(url)
+    assert resp.status_code == 404
+    assert resp.json() == {"detail": "Reconciliation entry not found"}

src/backend/core/tests/test_models_user_reconciliation.py

@@ -0,0 +1,669 @@
+"""
+Unit tests for the UserReconciliationCsvImport model
+"""
+
+import uuid
+from pathlib import Path
+
+from django.core import mail
+from django.core.files.base import ContentFile
+
+import pytest
+
+from core import factories, models
+from core.admin import process_reconciliation
+from core.tasks.user_reconciliation import user_reconciliation_csv_import_job
+
+pytestmark = pytest.mark.django_db
+
+
+@pytest.fixture(name="import_example_csv_basic")
+def fixture_import_example_csv_basic():
+    """
+    Import an example CSV file for user reconciliation
+    and return the created import object.
+    """
+    # Create users referenced in the CSV
+    for i in range(40, 50):
+        factories.UserFactory(email=f"user.test{i}@example.com")
+
+    example_csv_path = Path(__file__).parent / "data/example_reconciliation_basic.csv"
+    with open(example_csv_path, "rb") as f:
+        csv_file = ContentFile(f.read(), name="example_reconciliation_basic.csv")
+    csv_import = models.UserReconciliationCsvImport(file=csv_file)
+    csv_import.save()
+
+    return csv_import
+
+
+@pytest.fixture(name="import_example_csv_grist_form")
+def fixture_import_example_csv_grist_form():
+    """
+    Import an example CSV file for user reconciliation
+    and return the created import object.
+    """
+    # Create users referenced in the CSV
+    for i in range(10, 40):
+        factories.UserFactory(email=f"user.test{i}@example.com")
+
+    example_csv_path = (
+        Path(__file__).parent / "data/example_reconciliation_grist_form.csv"
+    )
+    with open(example_csv_path, "rb") as f:
+        csv_file = ContentFile(f.read(), name="example_reconciliation_grist_form.csv")
+    csv_import = models.UserReconciliationCsvImport(file=csv_file)
+    csv_import.save()
+
+    return csv_import
+
+
+def test_user_reconciliation_csv_import_entry_is_created(import_example_csv_basic):
+    """Test that a UserReconciliationCsvImport entry is created correctly."""
+    assert import_example_csv_basic.status == "pending"
+    assert import_example_csv_basic.file.name.endswith(
+        "example_reconciliation_basic.csv"
+    )
+
+
+def test_user_reconciliation_csv_import_entry_is_created_grist_form(
+    import_example_csv_grist_form,
+):
+    """Test that a UserReconciliationCsvImport entry is created correctly."""
+    assert import_example_csv_grist_form.status == "pending"
+    assert import_example_csv_grist_form.file.name.endswith(
+        "example_reconciliation_grist_form.csv"
+    )
+
+
+def test_incorrect_csv_format_handling():
+    """Test that an incorrectly formatted CSV file is handled gracefully."""
+    example_csv_path = (
+        Path(__file__).parent / "data/example_reconciliation_missing_column.csv"
+    )
+    with open(example_csv_path, "rb") as f:
+        csv_file = ContentFile(
+            f.read(), name="example_reconciliation_missing_column.csv"
+        )
+    csv_import = models.UserReconciliationCsvImport(file=csv_file)
+    csv_import.save()
+
+    assert csv_import.status == "pending"
+
+    user_reconciliation_csv_import_job(csv_import.id)
+    csv_import.refresh_from_db()
+
+    assert (
+        "CSV is missing mandatory columns: active_email, inactive_email, id"
+        in csv_import.logs
+    )
+    assert csv_import.status == "error"
+
+
+def test_incorrect_email_format_handling():
+    """Test that an incorrectly formatted CSV file is handled gracefully."""
+    example_csv_path = Path(__file__).parent / "data/example_reconciliation_error.csv"
+    with open(example_csv_path, "rb") as f:
+        csv_file = ContentFile(f.read(), name="example_reconciliation_error.csv")
+    csv_import = models.UserReconciliationCsvImport(file=csv_file)
+    csv_import.save()
+
+    assert csv_import.status == "pending"
+
+    user_reconciliation_csv_import_job(csv_import.id)
+    csv_import.refresh_from_db()
+
+    assert "Invalid inactive email address on row 40" in csv_import.logs
+    assert csv_import.status == "done"
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 1
+
+    # pylint: disable-next=no-member
+    email = mail.outbox[0]
+
+    assert email.to == ["user.test40@example.com"]
+    email_content = " ".join(email.body.split())
+
+    assert "Reconciliation of your Docs accounts not completed" in email_content
+
+
+def test_incorrect_csv_data_handling_grist_form():
+    """Test that a CSV file with incorrect data is handled gracefully."""
+    example_csv_path = (
+        Path(__file__).parent / "data/example_reconciliation_grist_form_error.csv"
+    )
+    with open(example_csv_path, "rb") as f:
+        csv_file = ContentFile(
+            f.read(), name="example_reconciliation_grist_form_error.csv"
+        )
+    csv_import = models.UserReconciliationCsvImport(file=csv_file)
+    csv_import.save()
+
+    assert csv_import.status == "pending"
+
+    user_reconciliation_csv_import_job(csv_import.id)
+    csv_import.refresh_from_db()
+
+    assert (
+        "user.test20@example.com set as both active and inactive email"
+        in csv_import.logs
+    )
+    assert csv_import.status == "done"
+
+
+def test_job_creates_reconciliation_entries(import_example_csv_basic):
+    """Test that the CSV import job creates UserReconciliation entries."""
+    assert import_example_csv_basic.status == "pending"
+    user_reconciliation_csv_import_job(import_example_csv_basic.id)
+
+    # Verify the job status changed
+    import_example_csv_basic.refresh_from_db()
+    assert import_example_csv_basic.status == "done"
+    assert "Import completed successfully." in import_example_csv_basic.logs
+    assert "6 rows processed." in import_example_csv_basic.logs
+    assert "5 reconciliation entries created." in import_example_csv_basic.logs
+
+    # Verify reconciliation entries were created
+    reconciliations = models.UserReconciliation.objects.all()
+    assert reconciliations.count() == 5
+
+
+def test_job_does_not_create_duplicated_reconciliation_entries(
+    import_example_csv_basic,
+):
+    """Test that the CSV import job doesn't create UserReconciliation entries
+    for source unique IDs that have already been processed."""
+
+    _already_created_entry = models.UserReconciliation.objects.create(
+        active_email="user.test40@example.com",
+        inactive_email="user.test41@example.com",
+        active_email_checked=0,
+        inactive_email_checked=0,
+        status="pending",
+        source_unique_id=1,
+    )
+
+    assert import_example_csv_basic.status == "pending"
+    user_reconciliation_csv_import_job(import_example_csv_basic.id)
+
+    # Verify the job status changed
+    import_example_csv_basic.refresh_from_db()
+    assert import_example_csv_basic.status == "done"
+    assert "Import completed successfully." in import_example_csv_basic.logs
+    assert "6 rows processed." in import_example_csv_basic.logs
+    assert "4 reconciliation entries created." in import_example_csv_basic.logs
+    assert "1 rows were already processed." in import_example_csv_basic.logs
+
+    # Verify the correct number of reconciliation entries were created
+    reconciliations = models.UserReconciliation.objects.all()
+    assert reconciliations.count() == 5
+
+
+def test_job_creates_reconciliation_entries_grist_form(import_example_csv_grist_form):
+    """Test that the CSV import job creates UserReconciliation entries."""
+    assert import_example_csv_grist_form.status == "pending"
+    user_reconciliation_csv_import_job(import_example_csv_grist_form.id)
+
+    # Verify the job status changed
+    import_example_csv_grist_form.refresh_from_db()
+    assert "Import completed successfully" in import_example_csv_grist_form.logs
+    assert import_example_csv_grist_form.status == "done"
+
+    # Verify reconciliation entries were created
+    reconciliations = models.UserReconciliation.objects.all()
+    assert reconciliations.count() == 9
+
+
+def test_csv_import_reconciliation_data_is_correct(import_example_csv_basic):
+    """Test that the data in created UserReconciliation entries matches the CSV."""
+    user_reconciliation_csv_import_job(import_example_csv_basic.id)
+
+    reconciliations = models.UserReconciliation.objects.order_by("created_at")
+    first_entry = reconciliations.first()
+
+    assert first_entry.active_email == "user.test40@example.com"
+    assert first_entry.inactive_email == "user.test41@example.com"
+    assert first_entry.active_email_checked is False
+    assert first_entry.inactive_email_checked is False
+
+    for rec in reconciliations:
+        assert rec.status == "ready"
+
+
+@pytest.fixture(name="user_reconciliation_users_and_docs")
+def fixture_user_reconciliation_users_and_docs():
+    """Fixture to create two users with overlapping document accesses
+    for reconciliation tests."""
+    user_1 = factories.UserFactory(email="user.test1@example.com")
+    user_2 = factories.UserFactory(email="user.test2@example.com")
+
+    # Create 10 distinct document accesses for each user
+    userdocs_u1 = [
+        factories.UserDocumentAccessFactory(user=user_1, role="editor")
+        for _ in range(10)
+    ]
+    userdocs_u2 = [
+        factories.UserDocumentAccessFactory(user=user_2, role="editor")
+        for _ in range(10)
+    ]
+
+    # Make the first 3 documents of each list shared with the other user
+    # with a lower role
+    for ud in userdocs_u1[0:3]:
+        factories.UserDocumentAccessFactory(
+            user=user_2, document=ud.document, role="reader"
+        )
+
+    for ud in userdocs_u2[0:3]:
+        factories.UserDocumentAccessFactory(
+            user=user_1, document=ud.document, role="reader"
+        )
+
+    # Make the next 3 documents of each list shared with the other user
+    # with a higher role
+    for ud in userdocs_u1[3:6]:
+        factories.UserDocumentAccessFactory(
+            user=user_2, document=ud.document, role="owner"
+        )
+
+    for ud in userdocs_u2[3:6]:
+        factories.UserDocumentAccessFactory(
+            user=user_1, document=ud.document, role="owner"
+        )
+
+    return (user_1, user_2, userdocs_u1, userdocs_u2)
+
+
+def test_user_reconciliation_is_created(user_reconciliation_users_and_docs):
+    """Test that a UserReconciliation entry can be created and saved."""
+    user_1, user_2, _userdocs_u1, _userdocs_u2 = user_reconciliation_users_and_docs
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_email_checked=False,
+        inactive_email_checked=True,
+        active_email_confirmation_id=uuid.uuid4(),
+        inactive_email_confirmation_id=uuid.uuid4(),
+        status="pending",
+    )
+
+    rec.save()
+    assert rec.status == "ready"
+
+
+def test_user_reconciliation_verification_emails_are_sent(
+    user_reconciliation_users_and_docs,
+):
+    """Test that both UserReconciliation verification emails are sent."""
+    user_1, user_2, _userdocs_u1, _userdocs_u2 = user_reconciliation_users_and_docs
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_email_checked=False,
+        inactive_email_checked=False,
+        active_email_confirmation_id=uuid.uuid4(),
+        inactive_email_confirmation_id=uuid.uuid4(),
+        status="pending",
+    )
+
+    rec.save()
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 2
+
+    # pylint: disable-next=no-member
+    email_1 = mail.outbox[0]
+
+    assert email_1.to == [user_1.email]
+    email_1_content = " ".join(email_1.body.split())
+
+    assert (
+        "You have requested a reconciliation of your user accounts on Docs."
+        in email_1_content
+    )
+    active_email_confirmation_id = rec.active_email_confirmation_id
+    inactive_email_confirmation_id = rec.inactive_email_confirmation_id
+    assert (
+        f"user-reconciliations/active/{active_email_confirmation_id}/"
+        in email_1_content
+    )
+
+    # pylint: disable-next=no-member
+    email_2 = mail.outbox[1]
+
+    assert email_2.to == [user_2.email]
+    email_2_content = " ".join(email_2.body.split())
+
+    assert (
+        "You have requested a reconciliation of your user accounts on Docs."
+        in email_2_content
+    )
+
+    assert (
+        f"user-reconciliations/inactive/{inactive_email_confirmation_id}/"
+        in email_2_content
+    )
+
+
+def test_user_reconciliation_only_starts_if_checks_are_made(
+    user_reconciliation_users_and_docs,
+):
+    """Test that the admin action does not process entries
+    unless both email checks are confirmed.
+    """
+    user_1, user_2, _userdocs_u1, _userdocs_u2 = user_reconciliation_users_and_docs
+
+    # Create a reconciliation entry where only one email has been checked
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_email_checked=True,
+        inactive_email_checked=False,
+        status="pending",
+    )
+    rec.save()
+
+    # Capture counts before running admin action
+    accesses_before_active = models.DocumentAccess.objects.filter(user=user_1).count()
+    accesses_before_inactive = models.DocumentAccess.objects.filter(user=user_2).count()
+    users_active_before = (user_1.is_active, user_2.is_active)
+
+    # Call the admin action with the queryset containing our single rec
+    qs = models.UserReconciliation.objects.filter(id=rec.id)
+    process_reconciliation(None, None, qs)
+
+    # Reload from DB and assert nothing was processed (checks prevent processing)
+    rec.refresh_from_db()
+    user_1.refresh_from_db()
+    user_2.refresh_from_db()
+
+    assert rec.status == "ready"
+    assert (
+        models.DocumentAccess.objects.filter(user=user_1).count()
+        == accesses_before_active
+    )
+    assert (
+        models.DocumentAccess.objects.filter(user=user_2).count()
+        == accesses_before_inactive
+    )
+    assert (user_1.is_active, user_2.is_active) == users_active_before
+
+
+def test_process_reconciliation_updates_accesses(
+    user_reconciliation_users_and_docs,
+):
+    """Test that accesses are consolidated on the active user."""
+    user_1, user_2, userdocs_u1, userdocs_u2 = user_reconciliation_users_and_docs
+
+    u1_2 = userdocs_u1[2]
+    u1_5 = userdocs_u1[5]
+    u2doc1 = userdocs_u2[1].document
+    u2doc5 = userdocs_u2[5].document
+
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_user=user_1,
+        inactive_user=user_2,
+        active_email_checked=True,
+        inactive_email_checked=True,
+        status="ready",
+    )
+
+    qs = models.UserReconciliation.objects.filter(id=rec.id)
+    process_reconciliation(None, None, qs)
+
+    rec.refresh_from_db()
+    user_1.refresh_from_db()
+    user_2.refresh_from_db()
+    u1_2.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+    u1_5.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+
+    # After processing, inactive user should have no accesses
+    # and active user should have one access per union document
+    # with the highest role
+    assert rec.status == "done"
+    assert "Requested update for 10 DocumentAccess items" in rec.logs
+    assert "and deletion for 12 DocumentAccess items" in rec.logs
+    assert models.DocumentAccess.objects.filter(user=user_2).count() == 0
+    assert models.DocumentAccess.objects.filter(user=user_1).count() == 20
+    assert u1_2.role == "editor"
+    assert u1_5.role == "owner"
+
+    assert (
+        models.DocumentAccess.objects.filter(user=user_1, document=u2doc1).first().role
+        == "editor"
+    )
+    assert (
+        models.DocumentAccess.objects.filter(user=user_1, document=u2doc5).first().role
+        == "owner"
+    )
+
+    assert user_1.is_active is True
+    assert user_2.is_active is False
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 1
+
+    # pylint: disable-next=no-member
+    email = mail.outbox[0]
+
+    assert email.to == [user_1.email]
+    email_content = " ".join(email.body.split())
+
+    assert "Your accounts have been merged" in email_content
+
+
+def test_process_reconciliation_updates_linktraces(
+    user_reconciliation_users_and_docs,
+):
+    """Test that linktraces are consolidated on the active user."""
+    user_1, user_2, userdocs_u1, userdocs_u2 = user_reconciliation_users_and_docs
+
+    u1_2 = userdocs_u1[2]
+    u1_5 = userdocs_u1[5]
+
+    doc_both = u1_2.document
+    models.LinkTrace.objects.create(document=doc_both, user=user_1)
+    models.LinkTrace.objects.create(document=doc_both, user=user_2)
+
+    doc_inactive_only = userdocs_u2[4].document
+    models.LinkTrace.objects.create(
+        document=doc_inactive_only, user=user_2, is_masked=True
+    )
+
+    doc_active_only = userdocs_u1[4].document
+    models.LinkTrace.objects.create(document=doc_active_only, user=user_1)
+
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_user=user_1,
+        inactive_user=user_2,
+        active_email_checked=True,
+        inactive_email_checked=True,
+        status="ready",
+    )
+
+    qs = models.UserReconciliation.objects.filter(id=rec.id)
+    process_reconciliation(None, None, qs)
+
+    rec.refresh_from_db()
+    user_1.refresh_from_db()
+    user_2.refresh_from_db()
+    u1_2.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+    u1_5.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+
+    # Inactive user should have no linktraces
+    assert models.LinkTrace.objects.filter(user=user_2).count() == 0
+
+    # doc_both should have a single LinkTrace owned by the active user
+    assert (
+        models.LinkTrace.objects.filter(user=user_1, document=doc_both).exists() is True
+    )
+    assert models.LinkTrace.objects.filter(user=user_1, document=doc_both).count() == 1
+    assert (
+        models.LinkTrace.objects.filter(user=user_2, document=doc_both).exists()
+        is False
+    )
+
+    # doc_inactive_only should now be linked to active user and preserve is_masked
+    lt = models.LinkTrace.objects.filter(
+        user=user_1, document=doc_inactive_only
+    ).first()
+    assert lt is not None
+    assert lt.is_masked is True
+
+    # doc_active_only should still belong to active user
+    assert models.LinkTrace.objects.filter(
+        user=user_1, document=doc_active_only
+    ).exists()
+
+
+def test_process_reconciliation_updates_threads_comments_reactions(
+    user_reconciliation_users_and_docs,
+):
+    """Test that threads, comments and reactions are transferred/deduplicated
+    on reconciliation."""
+    user_1, user_2, _userdocs_u1, userdocs_u2 = user_reconciliation_users_and_docs
+
+    # Use a document from the inactive user's set
+    document = userdocs_u2[0].document
+
+    # Thread and comment created by inactive user -> should be moved to active
+    thread = factories.ThreadFactory(document=document, creator=user_2)
+    comment = factories.CommentFactory(thread=thread, user=user_2)
+
+    # Reaction where only inactive user reacted -> should be moved to active user
+    reaction_inactive_only = factories.ReactionFactory(comment=comment, users=[user_2])
+
+    # Reaction where both users reacted -> inactive user's participation should be removed
+    thread2 = factories.ThreadFactory(document=document, creator=user_1)
+    comment2 = factories.CommentFactory(thread=thread2, user=user_1)
+    reaction_both = factories.ReactionFactory(comment=comment2, users=[user_1, user_2])
+
+    # Reaction where only active user reacted -> unchanged
+    thread3 = factories.ThreadFactory(document=document, creator=user_1)
+    comment3 = factories.CommentFactory(thread=thread3, user=user_1)
+    reaction_active_only = factories.ReactionFactory(comment=comment3, users=[user_1])
+
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_user=user_1,
+        inactive_user=user_2,
+        active_email_checked=True,
+        inactive_email_checked=True,
+        status="ready",
+    )
+
+    qs = models.UserReconciliation.objects.filter(id=rec.id)
+    process_reconciliation(None, None, qs)
+
+    # Refresh objects
+    thread.refresh_from_db()
+    comment.refresh_from_db()
+    reaction_inactive_only.refresh_from_db()
+    reaction_both.refresh_from_db()
+    reaction_active_only.refresh_from_db()
+
+    # Thread and comment creator should now be the active user
+    assert thread.creator == user_1
+    assert comment.user == user_1
+
+    # reaction_inactive_only: inactive user's participation should be removed and
+    # active user's participation added
+    reaction_inactive_only.refresh_from_db()
+    assert not reaction_inactive_only.users.filter(pk=user_2.pk).exists()
+    assert reaction_inactive_only.users.filter(pk=user_1.pk).exists()
+
+    # reaction_both: should end up with only active user's participation
+    assert reaction_both.users.filter(pk=user_2.pk).exists() is False
+    assert reaction_both.users.filter(pk=user_1.pk).exists() is True
+
+    # reaction_active_only should still have active user's participation
+    assert reaction_active_only.users.filter(pk=user_1.pk).exists()
+
+
+def test_process_reconciliation_updates_favorites(
+    user_reconciliation_users_and_docs,
+):
+    """Test that favorites are consolidated on the active user."""
+    user_1, user_2, userdocs_u1, userdocs_u2 = user_reconciliation_users_and_docs
+
+    u1_2 = userdocs_u1[2]
+    u1_5 = userdocs_u1[5]
+
+    doc_both = u1_2.document
+    models.DocumentFavorite.objects.create(document=doc_both, user=user_1)
+    models.DocumentFavorite.objects.create(document=doc_both, user=user_2)
+
+    doc_inactive_only = userdocs_u2[4].document
+    models.DocumentFavorite.objects.create(document=doc_inactive_only, user=user_2)
+
+    doc_active_only = userdocs_u1[4].document
+    models.DocumentFavorite.objects.create(document=doc_active_only, user=user_1)
+
+    rec = models.UserReconciliation.objects.create(
+        active_email=user_1.email,
+        inactive_email=user_2.email,
+        active_user=user_1,
+        inactive_user=user_2,
+        active_email_checked=True,
+        inactive_email_checked=True,
+        status="ready",
+    )
+
+    qs = models.UserReconciliation.objects.filter(id=rec.id)
+    process_reconciliation(None, None, qs)
+
+    rec.refresh_from_db()
+    user_1.refresh_from_db()
+    user_2.refresh_from_db()
+    u1_2.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+    u1_5.refresh_from_db(
+        from_queryset=models.DocumentAccess.objects.select_for_update()
+    )
+
+    # Inactive user should have no document favorites
+    assert models.DocumentFavorite.objects.filter(user=user_2).count() == 0
+
+    # doc_both should have a single DocumentFavorite owned by the active user
+    assert (
+        models.DocumentFavorite.objects.filter(user=user_1, document=doc_both).exists()
+        is True
+    )
+    assert (
+        models.DocumentFavorite.objects.filter(user=user_1, document=doc_both).count()
+        == 1
+    )
+    assert (
+        models.DocumentFavorite.objects.filter(user=user_2, document=doc_both).exists()
+        is False
+    )
+
+    # doc_inactive_only should now be linked to active user
+    assert (
+        models.DocumentFavorite.objects.filter(
+            user=user_2, document=doc_inactive_only
+        ).count()
+        == 0
+    )
+    assert models.DocumentFavorite.objects.filter(
+        user=user_1, document=doc_inactive_only
+    ).exists()
+
+    # doc_active_only should still belong to active user
+    assert models.DocumentFavorite.objects.filter(
+        user=user_1, document=doc_active_only
+    ).exists()

src/backend/core/tests/test_models_users.py

@@ -2,8 +2,6 @@
 Unit tests for the User model
 """
 
-from unittest import mock
-
 from django.core.exceptions import ValidationError
 
 import pytest
@@ -26,26 +24,6 @@ def test_models_users_id_unique():
         factories.UserFactory(id=user.id)
 
 
-def test_models_users_send_mail_main_existing():
-    """The "email_user' method should send mail to the user's email address."""
-    user = factories.UserFactory()
-
-    with mock.patch("django.core.mail.send_mail") as mock_send:
-        user.email_user("my subject", "my message")
-
-    mock_send.assert_called_once_with("my subject", "my message", None, [user.email])
-
-
-def test_models_users_send_mail_main_missing():
-    """The "email_user' method should fail if the user has no email address."""
-    user = factories.UserFactory(email=None)
-
-    with pytest.raises(ValueError) as excinfo:
-        user.email_user("my subject", "my message")
-
-    assert str(excinfo.value) == "User has no email address."
-
-
 @pytest.mark.parametrize(
     "sub,is_valid",
     [