Tests with coverage (#372)

* adding cabal-test alias to run test with coverage witout too much noise

* Define a cabal wrapper in the flake to remove annoying test junk output

---------

Co-authored-by: mmontin <mathieu.montin@tweag.io>

cabal.project

@@ -1,6 +1,10 @@
 packages:
   .
 
+package cooked-validators
+  coverage: True
+  library-coverage: True
+
 package cardano-crypto-praos
   flags: -external-libsodium-vrf
 
@@ -24,7 +28,6 @@ source-repository-package
 
 -- Everything below this point has been copied from plutus-apps' cabal.project
 
-
 -- Custom repository for cardano haskell packages
 -- See https://github.com/input-output-hk/cardano-haskell-packages on how to use CHaP in a Haskell project.
 repository cardano-haskell-packages

flake.nix

@@ -69,9 +69,23 @@
             ## one pinned by HLS.
             buildInputs = buildInputs ++ (with pkgs; [ ormolu hpack hlint ])
               ++ (with hpkgs; [ haskell-language-server ]);
-            inherit (pre-commit) shellHook;
+
             inherit LD_LIBRARY_PATH;
             inherit LANG;
+
+            # In addition to the pre-commit hooks, this redefines a cabal
+            # command that gets rid of annoying "Writing: .....*.html" output
+            # when running cabal test.
+            shellHook = pre-commit.shellHook + ''
+              function cabal() {
+                    if [ "$1" != "test" ]; then
+                      command cabal $@
+                    else
+                      command cabal --test-option=--color=always $@ | grep -vE --color=never "^Writing:.*html$"
+                    fi
+              }
+              export -f cabal
+            '';
           };
         };