channeldb/db: adds optional dry-run abort for migrations

channeldb/meta_test.go

@@ -12,13 +12,14 @@ import (
 // applyMigration is a helper test function that encapsulates the general steps
 // which are needed to properly check the result of applying migration function.
 func applyMigration(t *testing.T, beforeMigration, afterMigration func(d *DB),
-	migrationFunc migration, shouldFail bool) {
+	migrationFunc migration, shouldFail bool, dryRun bool) {
 
 	cdb, cleanUp, err := makeTestDB()
 	defer cleanUp()
 	if err != nil {
 		t.Fatal(err)
 	}
+	cdb.dryRun = dryRun
 
 	// Create a test node that will be our source node.
 	testNode, err := createTestVertex(cdb)
@@ -54,6 +55,9 @@ func applyMigration(t *testing.T, beforeMigration, afterMigration func(d *DB),
 
 	defer func() {
 		if r := recover(); r != nil {
+			if dryRun && r != ErrDryRunMigrationOK {
+				t.Fatalf("expected dry run migration OK")
+			}
 			err = errors.New(r)
 		}
 
@@ -256,7 +260,8 @@ func TestMigrationWithPanic(t *testing.T) {
 		beforeMigrationFunc,
 		afterMigrationFunc,
 		migrationWithPanic,
-		true)
+		true,
+		false)
 }
 
 // TestMigrationWithFatal asserts that migrations which fail do not modify the
@@ -330,7 +335,8 @@ func TestMigrationWithFatal(t *testing.T) {
 		beforeMigrationFunc,
 		afterMigrationFunc,
 		migrationWithFatal,
-		true)
+		true,
+		false)
 }
 
 // TestMigrationWithoutErrors asserts that a successful migration has its
@@ -404,6 +410,7 @@ func TestMigrationWithoutErrors(t *testing.T) {
 		beforeMigrationFunc,
 		afterMigrationFunc,
 		migrationWithoutErrors,
+		false,
 		false)
 }
 
@@ -446,3 +453,38 @@ func TestMigrationReversion(t *testing.T) {
 			"want: %v, got: %v", ErrDBReversion, err)
 	}
 }
+
+// TestMigrationDryRun ensures that opening the database in dry run migration
+// mode will fail and not commit the migration.
+func TestMigrationDryRun(t *testing.T) {
+	t.Parallel()
+
+	// Nothing to do, will inspect version number.
+	beforeMigrationFunc := func(d *DB) {}
+
+	// Check that version of database version is not modified.
+	afterMigrationFunc := func(d *DB) {
+		err := kvdb.View(d, func(tx kvdb.ReadTx) error {
+			meta, err := d.FetchMeta(nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if meta.DbVersionNumber != 0 {
+				t.Fatal("dry run migration was not aborted")
+			}
+
+			return nil
+		})
+		if err != nil {
+			t.Fatalf("unable to apply after func: %v", err)
+		}
+	}
+
+	applyMigration(t,
+		beforeMigrationFunc,
+		afterMigrationFunc,
+		func(kvdb.RwTx) error { return nil },
+		true,
+		true)
+}