Lambda Behave Framework overview

A modern testing and behavioural specification framework for Java 8
23 August 2017   471

Framework's goal is to make testing a more pleasant experience than it currently is.

One of the goals of the framework is to achieve great readability. The syntax encourages to describe test cases using full sentences rather just a few words.


The Lambda Behave Specification design has several goals:

  • To read like plain English.
  • To encourage describing tests using long and descriptive sentences, rather than a few words.
  • An API that is fluent and discoverable nearly entirely through IDE auto-completion.

There are many, many, expectations builtin to the framework - not just isEmpty().

Every specification suite starts its declaration using the Suite.describe method. From that point onwards your IDE should be able to auto-complete the domain specific language for declaring specifications, but just in case you want more information, here's the details.

  • If you want to specify a property about your system use it.should.
  • If you want describe an expectation of that property, use expect.that. This will get you to a fluent API restricted to the type of value that you're making the expectation about. The expectation system is based upon hamcrest. Lambda Behave doesn't compromise the ability to compose matchers in favour of fluency - if you want to compose in more complex flavours simply use expect.that(value).is() and then you can use regular Hamcrest matchers. In my experience this is a rare, albeit useful, breakout option.
  • If you want to setup or teardown data before or after each specification use it.isSetupWith and it.isConcludedWith.
  • If you want to setup or teardown data before or after each suite use it.initializesWith and it.completesWith.
  • Don't worry - I know some Java 8 lambdafied APIs don't deal with exceptions very well but you can throw exceptions in all our callbacks and the appropriate error will be reported, not just break the library.

More info available at GitHub

What is Web3j?

Small review of lightweight Java and Android library for integration with Ethereum clients
15 December 2017   817

What is webj3?

web3j is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network:

web3j architecture
Web3j Architecture

This allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.

According to the developers, these are the features:

  • Complete implementation of Ethereum's JSON-RPC client API over HTTP and IPC
  • Ethereum wallet support
  • Auto-generation of Java smart contract wrappers to create, deploy, transact with and call smart contracts from native Java code (Solidity and Truffle definition formats supported)
  • Reactive-functional API for working with filters
  • Ethereum Name Service (ENS) support
  • Support for Parity's Personal, and Geth's Personal client APIs
  • Support for Infura, so you don't have to run an Ethereum client yourself
  • Comprehensive integration tests demonstrating a number of the above scenarios
  • Command line tools
  • Android compatible
  • Support for JP Morgan's Quorum via web3j-quorum

It has five runtime dependencies:

  • RxJava for its reactive-functional API
  • OKHttp for HTTP connections
  • Jackson Core for fast JSON serialisation/deserialisation
  • Bouncy Castle (Spongy Castle on Android) for crypto
  • Jnr-unixsocket for *nix IPC (not available on Android)

It also uses JavaPoet for generating smart contract wrappers.

Lear more at GitHub.