DMD unittest fail reporting…

[Chris Wright via Digitalmars-d]

I quickly hacked up something to make assertions slightly more verbose: 
http://dpaste.dzfl.pl/f94b6ed80b3a

This can be extended quite a bit without a ton of effort, but it would 
eventually devolve into fully parsing D using compile-time function 
execution. Still, Catch can't even handle logical or, so it should be 
trivial to beat it in terms of quality of error reports. No real hope of 
matching Spock.

The interface leaves something to be desired:
mixin enforce!(q{i == j});

Say what you will, C preprocessor macros are very low on syntactic 
overhead.

The other ways I know of for passing in an expression involve eager 
evaluation or convert the expression to an opaque delegate. The mixin is 
required in order to access local variables.

The name "enforce" is obviously not appropriate, and it should ideally 
have pluggable error reporting mechanisms. But for a first hack, it's not 
so bad.

I might clean this up and put it on DUB.