Add backend code to transplant coverage reports from one commit to another

Author: Swatinem

services/report/tests/unit/test_transplant.py

@@ -0,0 +1,49 @@
+import pytest
+from shared.django_apps.core.tests.factories import (
+    CommitFactory,
+    CommitWithReportFactory,
+    RepositoryFactory,
+)
+from shared.django_apps.reports.models import ReportLevelTotals
+
+from services.archive import ArchiveService
+from services.report.transplant import transplant_commit_report
+
+
+@pytest.mark.django_db()
+def test_transplanting_commit(mock_storage):
+    repo = RepositoryFactory()
+    commit_from = CommitWithReportFactory(repository=repo)
+
+    archive_service = ArchiveService(repo)
+    with open("tasks/tests/samples/sample_chunks_1.txt", "rb") as f:
+        chunks = f.read()
+    archive_service.write_chunks(commit_from.commitid, chunks)
+
+    commit_to = CommitFactory(repository=repo)
+
+    transplant_commit_report(
+        repo_id=repo.repoid, from_sha=commit_from.commitid, to_sha=commit_to.commitid
+    )
+    commit_to.refresh_from_db()
+
+    from_totals = commit_from.commitreport.reportleveltotals
+    to_totals = commit_to.commitreport.reportleveltotals
+
+    def totals_tuple(totals: ReportLevelTotals):
+        return (
+            totals.branches,
+            totals.coverage,
+            totals.hits,
+            totals.lines,
+            totals.methods,
+            totals.misses,
+            totals.partials,
+            totals.files,
+        )
+
+    assert totals_tuple(from_totals) == totals_tuple(to_totals)
+
+    report = commit_to.full_report
+    file = report.get("tests/__init__.py")
+    assert file.get(1).coverage == 1

services/report/transplant.py

@@ -0,0 +1,52 @@
+from shared.django_apps.core.models import Commit
+from shared.django_apps.reports.models import CommitReport, ReportType
+
+from services.archive import ArchiveService
+
+
+def transplant_commit_report(repo_id: int, from_sha: str, to_sha: str):
+    """
+    This copies a `Report` from one commit to another commit.
+
+    The `to_sha` commit has to exist already (being auto-created using a git provider sync).
+
+    It does so by creating a copy of the underlying `report_json` and `chunks` storage files,
+    as well as some related DB models.
+    """
+
+    from_commit = Commit.objects.select_related("repository").get(
+        repository=repo_id, commitid=from_sha
+    )
+    to_commit = Commit.objects.get(repository=repo_id, commitid=to_sha)
+
+    archive_service = ArchiveService(from_commit.repository)
+
+    chunks = archive_service.read_chunks(from_commit.commitid)
+    report_json = from_commit.report
+    totals = from_commit.totals
+
+    archive_service.write_chunks(to_commit.commitid, chunks)
+
+    to_commit.report = report_json
+    to_commit.totals = totals
+    to_commit.state = "complete"
+    to_commit.save()
+
+    if old_commit_report := from_commit.commitreport:
+        commit_report = CommitReport(
+            commit=to_commit, report_type=ReportType.COVERAGE.value
+        )
+        commit_report.save()
+
+        if totals := old_commit_report.reportleveltotals:
+            # See <https://docs.djangoproject.com/en/5.1/topics/db/queries/#copying-model-instances>
+            totals.pk = None
+            totals.id = None
+            totals._state.adding = True
+
+            totals.report = commit_report
+            totals.save()
+
+    # TODO:
+    # We might also have to create copies of all of `Upload` (aka `Reportsession`),
+    # `UploadLevelTotals`, `UploadError` and `UploadFlagMembership`

tasks/compute_comparison.py

@@ -13,7 +13,7 @@
 from app import celery_app
 from database.enums import CompareCommitError, CompareCommitState
 from database.models import CompareCommit, CompareComponent, CompareFlag
-from database.models.reports import ReportLevelTotals, RepositoryFlag
+from database.models.reports import RepositoryFlag
 from helpers.comparison import minimal_totals
 from helpers.github_installation import get_installation_name_for_owner_for_task
 from rollouts import PARALLEL_COMPONENT_COMPARISON
@@ -216,7 +216,7 @@ def store_flag_comparison(
         db_session,
         comparison: CompareCommit,
         repositoryflag: RepositoryFlag,
-        totals: ReportLevelTotals,
+        totals,
     ):
         flag_comparison = CompareFlag(
             commit_comparison=comparison,