Test methods do not need to be named "test...".
Add tests for ImmutableStack.toString()
Add test for FifoQueue.toString()
Document why this unused class was created.
Flesh out some javadocs.
Remove unused method.
Removing a confusing newline.
Implement Walk.toString() and Step.toString()
Rename a method parameter to be more accurate.
Add test to make sure Walk.toString() does not throw exceptions.
Add unit tests for Lazy.
Use the enum singleton pattern for EmptyTraverser.
Rename some test graphs.
Add some comments separating sections testing each method.
Suppress a generic array warning.
Add test for Traversers.empty()
Rename test methods to match the graph being tested.
Factor out some common test code.
Rename "actual" to "expected", because I mixed that up.
Add a method for creating mutable test graphs to test remove().