phpspec is a tool which can help you write clean and working PHP code using behaviour driven development or BDD. BDD is a technique derived from test-first development.
BDD is a technique used at story level and spec level. phpspec is a tool for use at the spec level or SpecBDD. The technique is to first use a tool like phpspec to describe the behaviour of an object you are about to write. Next you write just enough code to meet that specification and finally you refactor this code.
There is no real difference between SpecBDD and TDD. The value of using an xSpec tool instead of a regular xUnit tool for TDD is the language. The early adopters of TDD focused on behaviour and design of code. Over time the focus has shifted towards verification and structure. BDD aims to shift the focus back by removing the language of testing. The concepts and features of the tool will keep your focus on the “right” things.
StoryBDD tools like Behat help to understand and clarify the domain. They help specify feature narratives, their needs, and what we mean by them. With SpecBDD we are only focused on the how, in other words, the implementation. You are specifying how your classes will achieve those features.
Only using story level BDD will not do enough to help you write the code for the features well. Each feature is likely to need quite a lot of code. If you only confirm that the whole feature works and also only refactor at that point then you are working in large steps. SpecBDD tools guide you in the process by letting you write the code in small steps. You only need to write the spec and then the code for the next small part you want to work on and not the whole feature.
StoryBDD and SpecBDD used together are an effective way to achieve customer-focused software.