throw error if a migration method doesn't return a thenable

src/migration.js

@@ -108,7 +108,11 @@ module.exports = class Migration {
     }
     if (!fun) throw new Error('Could not find migration method: ' + method);
     const wrappedFun = this.options.migrations.wrap(fun);
+    const result = wrappedFun.apply(migration, args);
+    if (!result || typeof result.then !== 'function') {
+      throw new Error(`Migration ${this.file} (or wrapper) didn't return a promise`);
+    }
 
-    await wrappedFun.apply(migration, args);
+    await result;
   }
 };

test/Umzug/execute.test.js

@@ -38,6 +38,33 @@ describe('execute', function () {
     this.migration.down.restore();
   });
 
+  it('requires migration methods to return a promise', function () {
+    helper.clearTmp();
+    helper
+      .prepareMigrations(1, { names: ['123-migration'], returnUndefined: true })
+      .then(() => {
+        this.migration = require('../tmp/123-migration.js');
+        this.upStub = sinon.stub(this.migration, 'up').callsFake(Bluebird.resolve);
+        this.downStub = sinon.stub(this.migration, 'down').callsFake(Bluebird.resolve);
+        this.logSpy = sinon.spy();
+        this.umzug = new Umzug({
+          migrations: { path: join(__dirname, '/../tmp/') },
+          storageOptions: { path: join(__dirname, '/../tmp/umzug.json') },
+          logging: this.logSpy,
+        });
+        return this.umzug.execute({
+          migrations: ['123-migration'],
+          method: 'up',
+        });
+      })
+      .then(() => {
+        throw new Error('expected migration to fail');
+      })
+      .catch(error => {
+        expect(error.message).to.match(/Migration 123-migration.js (or wrapper) didn't return a promise/i);
+      });
+  });
+
   it('runs the up method of the migration', function () {
     return this
       .migrate('up')
@@ -180,8 +207,8 @@ describe('coffee-script support', function () {
       '\'use strict\'',
       '',
       'module.exports =',
-      '  up: () ->',
-      '  down: () ->',
+      '  up: () -> Promise.resolve()',
+      '  down: () -> Promise.resolve()',
     ].join('\n')
     );
   });

test/helper.js

@@ -21,7 +21,7 @@ const helper = module.exports = {
     }
   },
 
-  generateDummyMigration: function (name, subDirectories) {
+  generateDummyMigration: function (name, subDirectories, options = {}) {
     let path = join(__dirname, '/tmp/');
     if (subDirectories) {
       if (!_.isArray(subDirectories)) {
@@ -40,8 +40,8 @@ const helper = module.exports = {
         '\'use strict\';',
         '',
         'module.exports = {',
-        '  up: function () {},',
-        '  down: function () {}',
+        `  up: function () { return ${options.returnUndefined ? 'undefined' : 'Promise.resolve()'}; },`,
+        `  down: function () { return ${options.returnUndefined ? 'undefined' : 'Promise.resolve()'}; }`,
         '};',
       ].join('\n')
     );
@@ -58,6 +58,7 @@ const helper = module.exports = {
       // example 3: ['foo',['foo','bar2']] ==> generates /foo and /foo/bar2
       ...options || {},
     };
+    const {returnUndefined} = options;
 
     return new Promise((resolve) => {
       let names = options.names;
@@ -68,7 +69,7 @@ const helper = module.exports = {
       _.times(count, (i) => {
         num++;
         names.push(options.names[i] || (num + '-migration'));
-        helper.generateDummyMigration(names[i], options.directories[i]);
+        helper.generateDummyMigration(names[i], options.directories[i], {returnUndefined});
       });
 
       resolve(names);