unlogged-sdk VS mockito-object-injection

Hello HN! Parth, and Shardul here. We have been building unlogged.io for the last 21 months. We started as a time travel debugger and pivoted to record and replay with assertions, mocking, and code coverage. You can save the replays in the form of a JSON and commit them to your git.

Both Parth and I come from an e-commerce/payments background where production bugs meant heavy financial losses. Big billion days/Black Friday sales meant months of code freezes with low productivity. Before committing the code, we wanted to replay production traffic and know the breaking changes right away, like in sub-second. Kind of like unit+integration tests on steroids.

So, we built an SDK that adds probes to the code in compile time. The SDK logs code execution, in detail.

Git: https://github.com/unloggedio/unlogged-sdk

We also built an IDE plugin that keeps monitoring code changes, hot reloads these changes, replays the relevant methods, and alerts on failing replays. It also lets developers call Java methods directly, mock downstream methods in run time, highlight code coverage in real-time, and show performance numbers for methods with inlay hints. (right above each method)

Git: https://github.com/unloggedio/intellij-java-plugin

We are excited to launch the first version of our product that replays with assertions + mocking + code coverage reports right inside the IDE.

Link to our IntelliJ plugin: https://plugins.jetbrains.com/plugin/18529-unlogged/

Record and Replay Demo: https://www.youtube.com/watch?v=muCyE-doEB0

Define Assertions on Replay: https://www.youtube.com/watch?v=YKsi1p634-M

Track Code Coverage: https://www.youtube.com/watch?v=NMmp954kfaU

Generate JUnit Test Cases: https://www.youtube.com/watch?v=rTUmg5b1Z_Q

Mocking when replaying: https://www.youtube.com/watch?v=O_aqU1u-Kmw

Documentation: http://read.unlogged.io/

Roadmap:

1. Create a production logger

Link to the source code: https://github.com/unloggedio/unlogged-sdk

will fix the link on the plugin page, thanks for noticing it.

This is pretty exciting... I've used them all libraries at this point in my career: CGLib, ASM, BCEL, ByteBuddy, Javassist, etc... each has its pluses and minuses. I've designed everything from profiling agents, to systems that pack decimals into EBCDIC and invoke COBOL programs on big IBM iron, to lightweight JIT compilers, all using these libraries.

> In 2002, the visitor approach used by ASM seemed clever

I couldn't agree more. The visitor pattern was very hard to explain/justify back then, and still difficult to explain to newbie programmers just entering the profession.

Looking at the examples, I think this is going to be an official replacement for ASM, meaning it's going to be pretty low level. The use of streams pretty straightforward.

If anyone from the JEP is reading this: I have two pieces of feedback!

First, take some inspiration from the way CDI Portable Extensions work. This is probably the most delightful extension API I've ever used. The @Observe callbacks are super simple to explain to people and it's really easy to write extensions for the framework.

Next, I wouldn't ignore the need for a higher-level API akin to ByteBuddy or Javassist. Sometimes I just want to write an interpreter or intercept a method call and thats it.

For example in my Junit/Mockito extension https://github.com/exabrial/mockito-object-injection I need to intercept a call to the class under test in order to lazily inject dependencies at the last possible moment. While I certainly could do this with ASM, Javassist makes this fairly simple with it's MethodHandler api.

Side note, it's a damn shame we don't have a mobile operating system that is JVM native :/ All this cool APIs simply never reach a huge number of devices.