feat(cli): support NodeJS callback style migration functions

.changeset/blue-steaks-hide.md

@@ -0,0 +1,5 @@
+---
+'@emigrate/cli': minor
+---
+
+Support migration functions using the old NodeJS callback style API, i.e. accepting a callback as a single parameter which in turns takes any error as its first parameter (any other parameters are ignored)

README.md

@@ -17,6 +17,7 @@ It's effectively a successor of [klei-migrate](https://www.npmjs.com/package/kle
   - Emigrate makes sure the migration history does not get stuck in a locked state if that's the case
 - Supports any file type for your migration files
   - You can easily write migrations in JavaScript, TypeScript or plain SQL (or any other language)
+  - JavaScript migration files written using CommonJS or ES modules (ESM) are supported out of the box
   - You can customize the template for your migration files to fit your needs (or use a plugin to do it for you)
 - Easy to debug
   - Emigrate will store any errors that occur during migration in the migration history so you can easily debug them

packages/cli/src/plugin-loader-js.ts

@@ -1,13 +1,29 @@
+import { promisify } from 'node:util';
 import { type LoaderPlugin } from '@emigrate/plugin-tools/types';
 
+// eslint-disable-next-line @typescript-eslint/ban-types
+const promisifyIfNeeded = <T extends Function>(fn: T) => {
+  if (fn.length === 0) {
+    return fn;
+  }
+
+  if (fn.length === 1) {
+    return promisify(fn);
+  }
+
+  throw new Error(
+    `Unexpected arguments length of migration function, expected 0 or 1 argument but got: ${fn.length} arguments`,
+  );
+};
+
 const loaderJs: LoaderPlugin = {
   loadableExtensions: ['.js', '.cjs', '.mjs'],
   async loadMigration(migration) {
     const migrationModule: unknown = await import(migration.filePath);
 
     if (typeof migrationModule === 'function') {
       return async () => {
-        await migrationModule();
+        await promisifyIfNeeded(migrationModule)();
       };
     }
 
@@ -19,7 +35,7 @@ const loaderJs: LoaderPlugin = {
     ) {
       const migrationFunction = migrationModule.default;
       return async () => {
-        await migrationFunction();
+        await promisifyIfNeeded(migrationFunction)();
       };
     }
 
@@ -31,7 +47,7 @@ const loaderJs: LoaderPlugin = {
     ) {
       const migrationFunction = migrationModule.up;
       return async () => {
-        await migrationFunction();
+        await promisifyIfNeeded(migrationFunction)();
       };
     }