Specify packages better and remove hpack defaults

CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## 0.1.2
+### Changed
+- Separate dependencies between library and tests.
+- Remove `hspec` default to prevent problems with Nix.
+
 ### Removed
 - Dependency to `cryptohash` not needed.
 

package.yaml

@@ -19,7 +19,6 @@ dependencies:
   - bytestring
   - cereal
   - entropy
-  - mtl
   - QuickCheck
   - string-conversions
 library:
@@ -27,7 +26,13 @@ library:
   extra-libraries: secp256k1
 tests:
   spec:
-    defaults: hspec/hspec@master
+    main: Spec.hs
+    source-dirs: test
+    verbatim:
+      build-tool-depends:
+          hspec-discover:hspec-discover
     dependencies:
+      - hspec
       - secp256k1-haskell
+      - mtl
       - HUnit