Add basic migration test

migrator.go

@@ -1,87 +1,86 @@
 package mysqlite
 
-//import (
-//	"database/sql"
-//	"embed"
-//	"fmt"
-//	"io/fs"
-//	"log"
-//	"strconv"
-//	"strings"
-//	"zombiezen.com/go/sqlite"
-//)
-//
-//type ReadDirFileFS interface {
-//	fs.ReadDirFS
-//	fs.ReadFileFS
-//}
-//
-//func (db *Db) MigrateDb(migrations ReadDirFileFS) error {
-//	// Read all migrations
-//	migrationFiles, err := migrations.ReadDir("")
-//	if err != nil {
-//		log.Fatalf("error reading migration files: %v", err)
-//	}
-//	var migrationsByVersion = make(map[int]string)
-//	latestVersion := 0
-//	for _, f := range migrationFiles {
-//		versionStr := f.Name()
-//		version, err := strconv.Atoi(strings.SplitN(versionStr, "_", 2)[0])
-//		if err != nil {
-//			log.Fatalf("invalid version number for migration script: %v", err)
-//		}
-//		migrationsByVersion[version] = versionStr
-//		latestVersion = max(latestVersion, version)
-//	}
-//
-//	// Get current migration version from user_version
-//	var currentVersion int
-//	err = d.QuerySingle("PRAGMA user_version", &currentVersion)
-//	if err != nil {
-//		log.Fatalf("error getting current version: %v", err)
-//	}
-//	log.Printf("Current database migration version is %d, latest version is %d", currentVersion, latestVersion)
-//
-//	// If we are no up-to-date, bring the db up-to-date
-//	for currentVersion != latestVersion {
-//		targetVersion := currentVersion + 1
-//		migrationFile := migrationsByVersion[targetVersion]
-//		log.Printf("migration to version %s", migrationFile)
-//		migrationScript, err := migrations.ReadFile(migrationFile)
-//		if err != nil {
-//			log.Fatalf("error opening migration script %s: %v", migrationScript, err)
-//		}
-//
-//		tx, err := db.Begin()
-//		if err != nil {
-//			log.Fatalf("error beginning transaction: %v", err)
-//		}
-//		defer tx.MustRollback()
-//
-//		err = tx.QuerySingle(string(migrationScript))
-//		if err != nil {
-//			log.Fatalf("error performing migration: %v", err)
-//		}
-//
-//		err = tx.QuerySingle(fmt.Sprintf("PRAGMA user_version = %d", targetVersion))
-//		if err != nil {
-//			log.Fatalf("error updating version: %v", err)
-//		}
-//
-//		err = tx.Commit()
-//		if err != nil {
-//			log.Fatalf("error commiting transaction: %v", err)
-//		}
-//		currentVersion = targetVersion
-//	}
-//
-//	log.Println("All migrations applied")
-//	return nil
-//}
-//
-//func rollbackIgnoringErrors(tx *sql.Tx) {
-//	err := tx.Rollback()
-//	if err != nil {
-//		log.Printf("error rolling back: %v", err)
-//	}
-//}
+import (
+	"fmt"
+	"io/fs"
+	"log"
+	"path"
+	"strconv"
+	"strings"
+)
+
+type ReadDirFileFS interface {
+	fs.ReadDirFS
+	fs.ReadFileFS
+}
+
+func (d *Db) MigrateDb(filesystem ReadDirFileFS, directory string) error {
+	// Read all migrations
+	migrationFiles, err := filesystem.ReadDir(directory)
+	if err != nil {
+		return fmt.Errorf("error reading migration files: %v", err)
+	}
+	var migrationsByVersion = make(map[int]string)
+	latestVersion := 0
+	for _, f := range migrationFiles {
+		versionStr := f.Name()
+		version, err := strconv.Atoi(strings.SplitN(versionStr, "_", 2)[0])
+		if err != nil {
+			return fmt.Errorf("invalid version number for migration script: %v", err)
+		}
+		migrationsByVersion[version] = versionStr
+		latestVersion = max(latestVersion, version)
+	}
+
+	// Get current migration version from user_version
+	var currentVersion int
+	err = d.Query("PRAGMA user_version").ScanSingle(&currentVersion)
+	if err != nil {
+		return fmt.Errorf("error getting current version: %v", err)
+	}
+	log.Printf("Current version is %d, max migration version is %d", currentVersion, latestVersion)
+
+	// If we are no up-to-date, bring the db up-to-date
+	for currentVersion != latestVersion {
+		targetVersion := currentVersion + 1
+		migrationFile := migrationsByVersion[targetVersion]
+		log.Printf("migrating to version %s", migrationFile)
+		migrationScript, err := filesystem.ReadFile(path.Join(directory, migrationFile))
+		if err != nil {
+			return fmt.Errorf("error opening migration script %s: %v", migrationScript, err)
+		}
+
+		err = performSingleMigration(err, d, migrationScript, targetVersion)
+		if err != nil {
+			return err
+		}
+		currentVersion = targetVersion
+	}
+
+	log.Println("Database is up-to-date")
+	return nil
+}
+
+func performSingleMigration(err error, d *Db, migrationScript []byte, targetVersion int) error {
+	tx, err := d.Begin()
+	if err != nil {
+		return fmt.Errorf("error beginning transaction: %v", err)
+	}
+	defer tx.MustRollback()
+
+	err = tx.Query(string(migrationScript)).Exec()
+	if err != nil {
+		return fmt.Errorf("error performing migration: %v", err)
+	}
+
+	err = tx.Query(fmt.Sprintf("PRAGMA user_version = %d", targetVersion)).Exec()
+	if err != nil {
+		return fmt.Errorf("error updating version: %v", err)
+	}
+
+	err = tx.Commit()
+	if err != nil {
+		return fmt.Errorf("error commiting transaction: %v", err)
+	}
+	return nil
+}

migrator_test.go

@@ -0,0 +1,20 @@
+package mysqlite
+
+import (
+	"embed"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+//go:embed testMigrations/*.sql
+var migrations embed.FS
+
+func TestDb_MigrateDb(t *testing.T) {
+	db := openEmptyTestDb(t)
+	err := db.MigrateDb(migrations, "testMigrations")
+	require.NoError(t, err)
+
+	var count int
+	db.Query("select count(*) from mydata").MustScanSingle(&count)
+	require.Equal(t, 1, count, "incorrect number of rows in database")
+}

testMigrations/1_initial.sql

@@ -0,0 +1,3 @@
+create table mydata (
+    value text
+)

testMigrations/2_addRow.sql

@@ -0,0 +1,2 @@
+insert into mydata (value)
+values ('hello')