Consider using test-assembler for tests

[luser]

I wrote a crate called test-assembler a while ago, ported from some C++ code a coworker wrote for the Breakpad project. It's got a fairly nice API for spelling out binary data for tests. gimli is using it for some tests, and I've also written tests for my rust-minidump crate with it.

It might be worth looking at for writing tests of various bits of parsing.