Encapsulate Composite with Builder is the refactoring described in Chapter 6 of the book Refactoring to Patterns.

The commits in this repository try to mimic the test-driven steps described in the example section of the chapter. The first commit represents the initial state with the Composite TagNode.

We report below the mechanics of this refactoring.

The following mechanics assume you already have Composite-construction code and you'd like to encapsulate this code with a Builder.

1. Create a builder, a new class that will become a Builder (see Design Patterns) by the end of this refactoring. Make it possible for your builder to produce a one-node Composite. Add a method to the builder to obtain the result of its build.

   ✅ Compile and test.

2. Make the builder capable of building children. This often involves creating multiple methods for allowing clients to easily direct the creation and positioning of children.

   ✅ Compile and test.

3. If the Composite-construction code you're replacing sets attributes or values on nodes, make the builder capable of settings those attributes and values.

   ✅ Compile and test.

4. Reflect on how simple your builder is for client to use, and then make it simpler.

   ✅ Compile and test.

5. Refactor your Composite-construction code to use the new builder. This involves making your client code what is knows in Design Patterns as a Builder:Client and Builder:Director.

   ✅ Compile and test.