Test for too old.

Author: AlphaOne1

migration.go

@@ -40,7 +40,7 @@ var ErrMigrationTableNameInvalid = errors.New("invalid migration table name")
 
 // ErrMigrationsTooOld signalizes that the migrations to be applied are older than the migrations that are already
 // present in the database. This error can occur when an older version of the application is started using a database
-// that was used already by a newer version of the appliction.
+// that was used already by a newer version of the application.
 var ErrMigrationsTooOld = errors.New("migrations too old")
 
 // Dialect is an interface describing the functionalities needed to manage migrations inside a database.
@@ -217,7 +217,7 @@ func (m *Morpher) applyMigrations(db *sql.DB, lastMigration string) error {
 
 		// even if we are sure to catch all possibilities, we use this as a safeguard that also with later
 		// modifications, if a successful commit cannot be done, at least the rollback is executed freeing
-		// allocated ressources of the transaction.
+		// allocated resources of the transaction.
 		defer func() { _ = tx.Rollback() }()
 
 		if err := migration.Migrate(tx); err != nil {
@@ -255,6 +255,8 @@ func (m *Morpher) checkAppliedMigrations(appliedMigrations []string) error {
 	}
 
 	if len(m.Migrations) < len(appliedMigrations) {
+		// it is impossible to have a migration newer than the one already applied
+		// without having at least the same amount of previous migrations
 		return ErrMigrationsUnrelated
 	}
 

migration_test.go

@@ -33,6 +33,7 @@ func prepareDB() (string, error) {
 	return result, nil
 }
 
+// TestMigration tests the happy flow.
 func TestMigration(t *testing.T) {
 	dbFile, dbFileErr := prepareDB()
 
@@ -62,3 +63,77 @@ func TestMigration(t *testing.T) {
 		t.Errorf("Migrations could not be run: %v", runErr)
 	}
 }
+
+// TestMigration tests what happens, if the applied migrations are too old.
+func TestMigrationTooOld(t *testing.T) {
+	dbFile, dbFileErr := prepareDB()
+
+	if dbFileErr != nil {
+		t.Errorf("DB file could not be created: %v", dbFileErr)
+	} else {
+		defer func() { _ = os.Remove(dbFile) }()
+	}
+
+	db, dbErr := sql.Open("sqlite", dbFile)
+
+	if dbErr != nil {
+		t.Errorf("DB file could not be created: %v", dbErr)
+	} else {
+		defer func() { _ = db.Close() }()
+	}
+
+	migrationsDir, migrationsDirErr := fs.Sub(testMigrationsDir, "testData")
+
+	assert.Nil(t, migrationsDirErr, "migrations directory could not be opened")
+
+	runErr := Run(db,
+		WithDialect(DialectSQLite()),
+		WithMigrationsFromFS(migrationsDir.(fs.ReadDirFS)))
+
+	if runErr != nil {
+		t.Errorf("preparation migrations could not be run: %v", runErr)
+	}
+
+	runErr = Run(db,
+		WithDialect(DialectSQLite()),
+		WithMigrationFromFileFS("01_base_table.sql", migrationsDir))
+
+	assert.ErrorIs(t, runErr, ErrMigrationsTooOld, "migrations did not give expected error")
+}
+
+// TestMigration tests what happens, if the applied migrations are unrelated to existing ones.
+func TestMigrationUnrelated(t *testing.T) {
+	dbFile, dbFileErr := prepareDB()
+
+	if dbFileErr != nil {
+		t.Errorf("DB file could not be created: %v", dbFileErr)
+	} else {
+		defer func() { _ = os.Remove(dbFile) }()
+	}
+
+	db, dbErr := sql.Open("sqlite", dbFile)
+
+	if dbErr != nil {
+		t.Errorf("DB file could not be created: %v", dbErr)
+	} else {
+		defer func() { _ = db.Close() }()
+	}
+
+	migrationsDir, migrationsDirErr := fs.Sub(testMigrationsDir, "testData")
+
+	assert.Nil(t, migrationsDirErr, "migrations directory could not be opened")
+
+	runErr := Run(db,
+		WithDialect(DialectSQLite()),
+		WithMigrationFromFileFS("01_base_table.sql", migrationsDir))
+
+	if runErr != nil {
+		t.Errorf("preparation migrations could not be run: %v", runErr)
+	}
+
+	runErr = Run(db,
+		WithDialect(DialectSQLite()),
+		WithMigrationFromFileFS("02_addon_table.sql", migrationsDir))
+
+	assert.ErrorIs(t, runErr, ErrMigrationsUnrelated, "migrations did not give expected error")
+}