easytest does not work with hedgehog 1.x (available on unstable).
Luckily, hledger (the only rev dep of easytest) replaced it with tasty:

https://github.com/simonmichael/hledger/commit/13a3542464de479e8

If easytest continues to be unmaintained, we may want to consider
removing it from Debian.

Dear submitter,

as the package haskell-easytest has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1011212

The version of this package that was in Debian prior to this removal
can still be found using http://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)