fix(invoke): write result as JSON to stdout, errors to stderr

lib/index.js

@@ -180,17 +180,17 @@ class ServerlessStepFunctions {
       .then(this.startExecution)
       .then(this.describeExecution)
       .then((result) => {
-        logger.log('');
+        process.stderr.write('\n');
         if (result.status === 'FAILED') {
           return this.getExecutionHistory()
             .then((error) => {
-              logger.log(_.merge(result, error.events[error.events.length - 1]
-                .executionFailedEventDetails));
+              process.stderr.write(`${JSON.stringify(_.merge(result, error.events[error.events.length - 1]
+                .executionFailedEventDetails), null, 2)}\n`);
               process.exitCode = 1;
             });
         }
 
-        logger.log(result);
+        process.stdout.write(`${JSON.stringify(result, null, 2)}\n`);
         return BbPromise.resolve();
       });
   }

lib/invoke/invoke.test.js

@@ -359,6 +359,66 @@ describe('invoke', () => {
         }));
   });
 
+  describe('#invoke()', () => {
+    let stdoutStub;
+    let stderrStub;
+
+    beforeEach(() => {
+      stdoutStub = sinon.stub(process.stdout, 'write');
+      stderrStub = sinon.stub(process.stderr, 'write');
+      serverlessStepFunctions.stateMachineArn = 'my-arn';
+      serverlessStepFunctions.executionArn = 'my-execution-arn';
+    });
+
+    afterEach(() => {
+      stdoutStub.restore();
+      stderrStub.restore();
+    });
+
+    it('should write JSON result to stdout on success', () => {
+      const result = { status: 'SUCCEEDED', output: '{"foo":"bar"}' };
+      sinon.stub(serverlessStepFunctions, 'getStateMachineArn').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'startExecution').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'describeExecution').returns(BbPromise.resolve(result));
+
+      return serverlessStepFunctions.invoke().then(() => {
+        expect(stdoutStub.calledOnce).to.be.equal(true);
+        const written = stdoutStub.firstCall.args[0];
+        expect(JSON.parse(written)).to.deep.equal(result);
+      });
+    });
+
+    it('should write error details to stderr and set exitCode=1 on failure', () => {
+      const executionResult = { status: 'FAILED', executionArn: 'my-execution-arn' };
+      const failedDetails = { error: 'SomeError', cause: 'Something went wrong' };
+      sinon.stub(serverlessStepFunctions, 'getStateMachineArn').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'startExecution').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'describeExecution').returns(BbPromise.resolve(executionResult));
+      sinon.stub(serverlessStepFunctions, 'getExecutionHistory').returns(BbPromise.resolve({
+        events: [{ executionFailedEventDetails: failedDetails }],
+      }));
+
+      return serverlessStepFunctions.invoke().then(() => {
+        expect(stdoutStub.called).to.be.equal(false);
+        expect(stderrStub.called).to.be.equal(true);
+        const written = stderrStub.args.find(args => args[0].includes('"FAILED"'));
+        expect(written).to.not.equal(undefined);
+        expect(process.exitCode).to.equal(1);
+      });
+    });
+
+    it('should write newline to stderr after progress dots', () => {
+      const result = { status: 'SUCCEEDED' };
+      sinon.stub(serverlessStepFunctions, 'getStateMachineArn').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'startExecution').returns(BbPromise.resolve());
+      sinon.stub(serverlessStepFunctions, 'describeExecution').returns(BbPromise.resolve(result));
+
+      return serverlessStepFunctions.invoke().then(() => {
+        expect(stderrStub.calledWith('\n')).to.be.equal(true);
+      });
+    });
+  });
+
   describe('#setTimeout()', () => {
     let clock;