Try every event database file on delete and say which was left (closes #275)

DeleteDB returned on the first event database file it failed to remove, so with WAL sidecars present a failure could be reported as "the file was left behind" after the events themselves were already gone. It now tries the database file and both sidecars, and its error says which case happened and names each file left: the database file is still on disk, or it is gone (the events are lost) and only a -wal or -shm sidecar remains. The webhook delete handler logs a different message for each and never says the events survive when they do not. Tests cover a normal delete with both sidecars, and a failed removal of the database file or a sidecar, through DeleteDB and the handler.

Model: opus-5-5

internal/database/webhook_db_manager_test.go

@@ -182,17 +182,91 @@ func TestWebhookDBManager_DeleteDB(t *testing.T) {
 	}
 	require.NoError(t, db.Create(event).Error)
 
+	// Under WAL, an open database that has been written to has both
+	// sidecars beside it.
+	dbPath := mgr.DBPath(webhookID)
+	require.FileExists(t, dbPath+"-wal")
+	require.FileExists(t, dbPath+"-shm")
+
 	// Delete the DB
 	require.NoError(t, mgr.DeleteDB(webhookID))
 
 	// File should no longer exist
 	assert.False(t, mgr.DBExists(webhookID))
 
-	// Verify the file is actually gone from disk
+	// Verify the files are actually gone from disk
+	assert.NoFileExists(t, dbPath)
+	assert.NoFileExists(t, dbPath+"-wal")
+	assert.NoFileExists(t, dbPath+"-shm")
+}
+
+// blockRemoval puts a non-empty directory at path, which os.Remove
+// cannot remove whoever runs the test, root included.
+func blockRemoval(t *testing.T, path string) {
+	t.Helper()
+
+	require.NoError(t, os.MkdirAll(filepath.Join(path, "keep"), 0o700))
+}
+
+// TestWebhookDBManager_DeleteDBKeepsDatabaseFile proves that when the
+// event database file cannot be removed, the error says so, and both
+// sidecars are still removed.
+func TestWebhookDBManager_DeleteDBKeepsDatabaseFile(t *testing.T) {
+	t.Parallel()
+
+	mgr, lc := setupTestWebhookDBManager(t)
+	ctx := context.Background()
+	require.NoError(t, lc.Start(ctx))
+
+	defer func() { require.NoError(t, lc.Stop(ctx)) }()
+
+	webhookID := uuid.New().String()
 	dbPath := mgr.DBPath(webhookID)
 
-	_, err = os.Stat(dbPath)
-	assert.True(t, os.IsNotExist(err))
+	blockRemoval(t, dbPath)
+	require.NoError(t, os.WriteFile(dbPath+"-wal", nil, 0o600))
+	require.NoError(t, os.WriteFile(dbPath+"-shm", nil, 0o600))
+
+	err := mgr.DeleteDB(webhookID)
+
+	require.ErrorIs(t, err, database.ErrEventDBNotRemoved)
+	require.NotErrorIs(t, err, database.ErrSidecarNotRemoved)
+	assert.Contains(t, err.Error(), dbPath)
+	assert.NoFileExists(t, dbPath+"-wal")
+	assert.NoFileExists(t, dbPath+"-shm")
+}
+
+// TestWebhookDBManager_DeleteDBKeepsSidecar proves that when the
+// event database file is removed but a sidecar is not, the error
+// says the database file is gone, and the other sidecar is still
+// removed.
+func TestWebhookDBManager_DeleteDBKeepsSidecar(t *testing.T) {
+	t.Parallel()
+
+	mgr, lc := setupTestWebhookDBManager(t)
+	ctx := context.Background()
+	require.NoError(t, lc.Start(ctx))
+
+	defer func() { require.NoError(t, lc.Stop(ctx)) }()
+
+	webhookID := uuid.New().String()
+	dbPath := mgr.DBPath(webhookID)
+
+	require.NoError(t, mgr.CreateDB(webhookID))
+	// Closing removes the sidecars, so the ones below are the only
+	// ones there.
+	require.NoError(t, mgr.CloseAll())
+
+	blockRemoval(t, dbPath+"-wal")
+	require.NoError(t, os.WriteFile(dbPath+"-shm", nil, 0o600))
+
+	err := mgr.DeleteDB(webhookID)
+
+	require.ErrorIs(t, err, database.ErrSidecarNotRemoved)
+	require.NotErrorIs(t, err, database.ErrEventDBNotRemoved)
+	assert.Contains(t, err.Error(), dbPath+"-wal")
+	assert.NoFileExists(t, dbPath)
+	assert.NoFileExists(t, dbPath+"-shm")
 }
 
 func TestWebhookDBManager_LazyCreation(t *testing.T) {