Ahh, that makes more sense.
What I'm thinking is a bunch of blocks, some valid, some not. You'd have transactions, some valid, some not. Things like orphan blocks would be present. I'm still really new to this, so I can't really give a full list of what all would comprise a representative sample.
You could feed this data into a parser, yes. You could also feed it into a system that validates blocks, another that deals with constructing the blockchain and handling orphans, etc. You could make a mini unit test network consisting of a couple of nodes broadcasting the test data blocks, and use that to validate node functionality.
The expected results could even be described in some kind of format so that different implementations written in different languages could leverage this same set of test data, creating a validation suite of sorts.