Subclasses of Source MUST override this method.
Subclasses of Source MUST override this method. They may call out to TestTapFactory for making Taps suitable for testing.
The mock passed in to scalding.
The mock passed in to scalding.JobTest may be considered as a mock of the Tap or the Source. By default, as of 0.9.0, it is considered as a Mock of the Source. If you set this to true, the mock in TestMode will be considered to be a mock of the Tap (which must be transformed) and not the Source.
write the pipe but return the input so it can be chained into the next operation
(Since version 0.9.0) replace with Mappable.toIterator
Every source must have a correct toString method. If you use case classes for instances of sources, you will get this for free. This is one of the several reasons we recommend using cases classes
java.io.Serializable is needed if the Source is going to have any methods attached that run on mappers or reducers, which will happen if you implement transformForRead or transformForWrite.