Support async lambda functions

Author: mantoni

lib/runner.js

@@ -26,9 +26,21 @@ process.on('message', (m) => {
     get: invokedFunctionArn
   });
   setGetRemainingTimeInMillis(context);
-  lambda_module.handle(m.event, context, (err, data) => {
+
+  function handleResponse(err, data) {
     const res = data ? JSON.stringify(data) : null;
     const mem = process.memoryUsage();
     process.send({ id: m.id, err, res, mem });
-  });
+  }
+
+  if (lambda_module.handle.length < 3) {
+    lambda_module
+      .handle(m.event, context)
+      .then((data) => {
+        handleResponse(null, data);
+      })
+      .catch(handleResponse);
+  } else {
+    lambda_module.handle(m.event, context, handleResponse);
+  }
 });

test/fixture/functions/hello-async/index.js

@@ -0,0 +1,9 @@
+'use strict';
+
+exports.handle = function (event) {
+  return new Promise((resolve) => {
+    setTimeout(() => {
+      resolve(`Hello ${event.name}`);
+    }, 1);
+  });
+};

test/fixture/functions/throw-async/index.js

@@ -0,0 +1,5 @@
+'use strict';
+
+exports.handle = function () {
+  throw new Error('Oh noes!');
+};

test/fixture/functions/throw/index.js

@@ -1,5 +1,5 @@
 'use strict';
 
-exports.handle = function () {
+exports.handle = function (_event, _context, _callback) {
   throw new Error('Oh noes!');
 };

test/lambda-test.js

@@ -32,6 +32,20 @@ describe('lambda', () => {
     });
   });
 
+  it('invokes async lambda', (done) => {
+    lambda = Lambda.create();
+
+    lambda.invoke(
+      'hello-async',
+      { name: 'JavaScript Studio' },
+      (err, value) => {
+        assert.isNull(err);
+        assert.equals(value, 'Hello JavaScript Studio');
+        done();
+      }
+    );
+  });
+
   it('handles invalid response', (done) => {
     lambda = Lambda.create();
 
@@ -513,7 +527,7 @@ describe('lambda', () => {
     });
   });
 
-  it('handled dying lambda', (done) => {
+  it('handles throwing lambda', (done) => {
     sinon.stub(process.stderr, 'write');
 
     lambda = Lambda.create();
@@ -524,6 +538,17 @@ describe('lambda', () => {
     });
   });
 
+  it('handles throwing async lambda', (done) => {
+    sinon.stub(process.stderr, 'write');
+
+    lambda = Lambda.create();
+
+    lambda.invoke('throw-async', {}, (err) => {
+      assert.json(err, { code: 'ERR_FAILED' });
+      done();
+    });
+  });
+
   it('runs node process with default memory', (done) => {
     lambda = Lambda.create({});