restic prune integration tests:

added one test TestPruneSizeMonitoring() which runs a failed backup and then calls prune
to remove the partial snapshot.

cmd/restic/integration_test needed to be modified, since it does not allow multiple calls
to list snapshots.

cmd/restic/cmd_prune_integration_test.go

@@ -8,13 +8,14 @@ import (
 
 	"github.com/restic/restic/internal/backend"
 	"github.com/restic/restic/internal/repository"
+	//"github.com/restic/restic/internal/restic"
 	rtest "github.com/restic/restic/internal/test"
 	"github.com/restic/restic/internal/ui/termstatus"
 )
 
 func testRunPrune(t testing.TB, gopts GlobalOptions, opts PruneOptions) {
 	oldHook := gopts.backendTestHook
-	gopts.backendTestHook = func(r backend.Backend) (backend.Backend, error) { return newListOnceBackend(r), nil }
+	gopts.backendTestHook = func(r backend.Backend) (backend.Backend, error) { return newListMultipleBackend(r), nil }
 	defer func() {
 		gopts.backendTestHook = oldHook
 	}()
@@ -142,7 +143,7 @@ func TestPruneWithDamagedRepository(t *testing.T) {
 	removePacksExcept(env.gopts, t, oldPacks, false)
 
 	oldHook := env.gopts.backendTestHook
-	env.gopts.backendTestHook = func(r backend.Backend) (backend.Backend, error) { return newListOnceBackend(r), nil }
+	env.gopts.backendTestHook = func(r backend.Backend) (backend.Backend, error) { return newListMultipleBackend(r), nil }
 	defer func() {
 		env.gopts.backendTestHook = oldHook
 	}()
@@ -237,3 +238,28 @@ func testEdgeCaseRepo(t *testing.T, tarfile string, optionsCheck CheckOptions, o
 			"prune should have reported an error")
 	}
 }
+
+func TestPruneSizeMonitoring(t *testing.T) {
+	env, cleanup := withTestEnvironment(t)
+	defer cleanup()
+
+	datafile := filepath.Join("testdata", "backup-data.tar.gz")
+	testRunInit(t, env.gopts)
+
+	rtest.SetupTarTestFixture(t, env.testdata, datafile)
+	opts := BackupOptions{RepoMaxSize: "50k"}
+
+	// create and delete snapshot to create unused blobs
+	oldHook := env.gopts.backendTestHook
+	env.gopts.backendTestHook = func(r backend.Backend) (backend.Backend, error) { return newListMultipleBackend(r), nil }
+	defer func() {
+		env.gopts.backendTestHook = oldHook
+	}()
+	err := testRunBackupAssumeFailure(t, filepath.Dir(env.testdata), []string{env.testdata}, opts, env.gopts)
+	rtest.Assert(t, err != nil, "backup should have ended in failure '%v'", err)
+	firstSnapshot := testListSnapshots(t, env.gopts, 1)[0]
+	t.Logf("first snapshot %v", firstSnapshot)
+
+	testRunPrune(t, env.gopts, PruneOptions{MaxUnused: "0"})
+	_ = testListSnapshots(t, env.gopts, 0)
+}

cmd/restic/integration_test.go

@@ -46,15 +46,20 @@ type listOnceBackend struct {
 	backend.Backend
 	listedFileType map[restic.FileType]bool
 	strictOrder    bool
+	allowMultiple  bool
 }
 
-func newListOnceBackend(be backend.Backend) *listOnceBackend {
+// the linter bites here: says newListOnceBackend is not used
+// I need to be able to call SnapshotLister more than once to check for partial snapshots
+// and restic prune uses `getUsedBlobs` to get all used blobs which uses
+// `restic.ForAllSnapshots()` to do the work.
+/*func newListOnceBackend(be backend.Backend) *listOnceBackend {
 	return &listOnceBackend{
 		Backend:        be,
 		listedFileType: make(map[restic.FileType]bool),
 		strictOrder:    false,
 	}
-}
+}*/
 
 func newOrderedListOnceBackend(be backend.Backend) *listOnceBackend {
 	return &listOnceBackend{
@@ -64,6 +69,15 @@ func newOrderedListOnceBackend(be backend.Backend) *listOnceBackend {
 	}
 }
 
+func newListMultipleBackend(be backend.Backend) *listOnceBackend {
+	return &listOnceBackend{
+		Backend:        be,
+		listedFileType: make(map[restic.FileType]bool),
+		strictOrder:    false,
+		allowMultiple:  true,
+	}
+}
+
 func (be *listOnceBackend) List(ctx context.Context, t restic.FileType, fn func(backend.FileInfo) error) error {
 	if t != restic.LockFile && be.listedFileType[t] {
 		return errors.Errorf("tried listing type %v the second time", t)
@@ -71,7 +85,9 @@ func (be *listOnceBackend) List(ctx context.Context, t restic.FileType, fn func(
 	if be.strictOrder && t == restic.SnapshotFile && be.listedFileType[restic.IndexFile] {
 		return errors.Errorf("tried listing type snapshots after index")
 	}
-	be.listedFileType[t] = true
+	if !be.allowMultiple {
+		be.listedFileType[t] = true
+	}
 	return be.Backend.List(ctx, t, fn)
 }