Awesome

BlobStore

A local, non thread-safe implementation of a key / value blobs storage in Java.

This is not mean to be bulletproof: this project purpose is to illustrate the benefits of using JBoss Byteman to harness unit and functional test suites by injecting faults.

There are many cases where exceptional behaviour is hard to reproduce in tests, especially when I/O and multiple threads are involved. JBoss Byteman manipulates application bytecode through event/condition/action rules, and can make it very easy to inject faults, wait/pause threads and so on.

Discussion

The master branch contains the latest iterations over the code base and tests suite.

The without-byteman branch contains the initial code base that was developed with traditional unit tests, without fault injection.

By comparing both branches, you can see how introducing faults with Byteman helped in:

• vastly increasing code coverage, and
• detecting a few bugs.

One may argue that the without-byteman branch could still be improved without Byteman, and that the few bugs fixed afterwards in the master branch could still have been spotted through peer-review.

This is true.

The point is that the without-byteman branch still had a reasonable code coverage to begin with, with the missing spots lying in I/O errors that would be very hard to introduce through even with object stubs/mocks.

Forcing a filesystem to refuse renaming a file, or forcing it to become full all of a sudden is definitely non-trivial.

If you have experience with other techniques than leveraging a bytecode manipulation tool like Byteman then I am very interested in hearing from you!

License

Copyright (c) 2012 Julien Ponge.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Building

The JBoss repositories can be boring to configure right with Maven, especially if you want to avoid putting explicit repository references in your POMs, which is bad practice anyway.

Read on this JBoss documentation.

You can contribute!

Although this project is a use-case rather than a real attempt at making a rock-solid blob storage engine, feel-free to propose enhancements.