test(document): integration-test title backfill against real Postgres (#726)

Pins backfill behaviour on postgres:16-alpine (H2 unusable — title is NOT NULL): a stale
auto-title is rewritten, the sweep is idempotent (second run touches nothing), prose is
left alone, and the mechanical rename adds no document_versions rows. Permission (401/403)
stays in the faster @WebMvcTest slice.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/test/java/org/raddatz/familienarchiv/document/DocumentTitleBackfillIntegrationTest.java

@@ -0,0 +1,90 @@
+package org.raddatz.familienarchiv.document;
+
+import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.PostgresContainerConfig;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.transaction.annotation.Transactional;
+import software.amazon.awssdk.services.s3.S3Client;
+
+import java.time.LocalDate;
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * End-to-end backfill against a real Postgres (#726, FR-003). H2 is unusable here — the
+ * {@code title} column is NOT NULL and the title-sync semantics depend on that — so this pins the
+ * behaviour on {@code postgres:16-alpine}: a stale auto-title is rewritten, the sweep is
+ * idempotent, prose is left alone, and the mechanical rename writes no {@code document_versions}
+ * rows. Permission enforcement (401/403) is covered faster by the {@code @WebMvcTest} slice in
+ * {@code AdminControllerTest}.
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
+@ActiveProfiles("test")
+@Import(PostgresContainerConfig.class)
+@Transactional
+class DocumentTitleBackfillIntegrationTest {
+
+    @MockitoBean S3Client s3Client;
+    @Autowired DocumentService documentService;
+    @Autowired DocumentRepository documentRepository;
+    @Autowired DocumentVersionRepository documentVersionRepository;
+
+    private Document persist(String index, String title, LocalDate date, DatePrecision precision, String location) {
+        return documentRepository.save(Document.builder()
+                .originalFilename(index)
+                .title(title)
+                .documentDate(date)
+                .metaDatePrecision(precision)
+                .location(location)
+                .status(DocumentStatus.PLACEHOLDER)
+                .build());
+    }
+
+    @Test
+    void backfill_rewritesStaleAutoTitle() {
+        Document stale = persist("C-0029", "C-0029 – 2028 – Berlin",
+                LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        int count = documentService.backfillTitles();
+
+        assertThat(count).isGreaterThanOrEqualTo(1);
+        assertThat(documentRepository.findById(stale.getId()).orElseThrow().getTitle())
+                .isEqualTo("C-0029 – 1928 – Berlin");
+    }
+
+    @Test
+    void backfill_isIdempotent_secondRunChangesNothing() {
+        persist("C-0029", "C-0029 – 2028 – Berlin", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+
+        documentService.backfillTitles();
+        int secondRun = documentService.backfillTitles();
+
+        assertThat(secondRun).isZero();
+    }
+
+    @Test
+    void backfill_skipsProse() {
+        Document prose = persist("C-0030", "C-0030 – Brief an Mutter",
+                LocalDate.of(1928, 1, 1), DatePrecision.YEAR, null);
+
+        documentService.backfillTitles();
+
+        assertThat(documentRepository.findById(prose.getId()).orElseThrow().getTitle())
+                .isEqualTo("C-0030 – Brief an Mutter");
+    }
+
+    @Test
+    void backfill_addsNoDocumentVersionRows() {
+        persist("C-0029", "C-0029 – 2028 – Berlin", LocalDate.of(1928, 1, 1), DatePrecision.YEAR, "Berlin");
+        long versionsBefore = documentVersionRepository.count();
+
+        documentService.backfillTitles();
+
+        assertThat(documentVersionRepository.count()).isEqualTo(versionsBefore);
+    }
+}