Add ModeDrop

dbump.go

@@ -57,6 +57,10 @@ type Migrator interface {
 	// and might be different between databases.
 	Init(ctx context.Context) error
 
+	// Drop is used only in ModeDrop to remove dbump database.
+	// Before drop all the migrations will be reverted (as for ModeDown).
+	Drop(ctx context.Context) error
+
 	// Version of the migration. Used only once in the beginning.
 	Version(ctx context.Context) (version int, err error)
 
@@ -94,6 +98,7 @@ const (
 	ModeUpOne
 	ModeDownOne
 	ModeRedo
+	ModeDrop
 	modeMaxPossible
 )
 
@@ -184,6 +189,10 @@ func (m *mig) runMigrations(ctx context.Context, ms []*Migration) (err error) {
 		return fmt.Errorf("init: %w", err)
 	}
 	err = m.runMigrationsLocked(ctx, ms)
+
+	if m.Mode == ModeDrop {
+		err = m.Drop(ctx)
+	}
 	return err
 }
 
@@ -207,7 +216,7 @@ func (m *mig) getCurrAndTargetVersions(ctx context.Context, migrations int) (cur
 		return 0, 0, fmt.Errorf("get version: %w", err)
 	}
 
-	switch m.Config.Mode {
+	switch m.Mode {
 	case ModeUp:
 		target = migrations
 		if curr > target {
@@ -238,6 +247,9 @@ func (m *mig) getCurrAndTargetVersions(ctx context.Context, migrations int) (cur
 		}
 		target = curr
 
+	case ModeDrop:
+		target = 0
+
 	default:
 		panic("unreachable")
 	}
@@ -302,6 +314,7 @@ func (llm *locklessMigrator) LockDB(ctx context.Context) error   { return nil }
 func (llm *locklessMigrator) UnlockDB(ctx context.Context) error { return nil }
 
 func (llm *locklessMigrator) Init(ctx context.Context) error { return llm.m.Init(ctx) }
+func (llm *locklessMigrator) Drop(ctx context.Context) error { return llm.m.Drop(ctx) }
 
 func (llm *locklessMigrator) Version(ctx context.Context) (version int, err error) {
 	return llm.m.Version(ctx)

dbump_test.go

@@ -204,6 +204,32 @@ func TestMigrateRedo(t *testing.T) {
 	mustEqual(t, mm.log, wantLog)
 }
 
+func TestMigrateDrop(t *testing.T) {
+	currVersion := 3
+	wantLog := []string{
+		"lockdb", "init", "getversion",
+		"dostep", "{v:2 q:'SELECT 30;' notx:false}",
+		"dostep", "{v:1 q:'SELECT 20;' notx:false}",
+		"dostep", "{v:0 q:'SELECT 10;' notx:false}",
+		"drop",
+		"unlockdb",
+	}
+
+	mm := &MockMigrator{
+		VersionFn: func(ctx context.Context) (version int, err error) {
+			return currVersion, nil
+		},
+	}
+	cfg := Config{
+		Migrator: mm,
+		Loader:   NewSliceLoader(testdataMigrations),
+		Mode:     ModeDrop,
+	}
+
+	failIfErr(t, Run(context.Background(), cfg))
+	mustEqual(t, mm.log, wantLog)
+}
+
 func TestUseForce(t *testing.T) {
 	currVersion := 3
 	wantLog := []string{

mock_test.go

@@ -13,6 +13,7 @@ type MockMigrator struct {
 	LockDBFn   func(ctx context.Context) error
 	UnlockDBFn func(ctx context.Context) error
 	InitFn     func(ctx context.Context) error
+	DropFn     func(ctx context.Context) error
 	VersionFn  func(ctx context.Context) (version int, err error)
 	DoStepFn   func(ctx context.Context, step Step) error
 }
@@ -41,6 +42,14 @@ func (mm *MockMigrator) Init(ctx context.Context) error {
 	return mm.InitFn(ctx)
 }
 
+func (mm *MockMigrator) Drop(ctx context.Context) error {
+	mm.log = append(mm.log, "drop")
+	if mm.DropFn == nil {
+		return nil
+	}
+	return mm.DropFn(ctx)
+}
+
 func (mm *MockMigrator) Version(ctx context.Context) (version int, err error) {
 	mm.log = append(mm.log, "getversion")
 	if mm.VersionFn == nil {