Simplify coverage Nix logic

Author: sevanspowell

lib/cover.nix

@@ -7,12 +7,34 @@
 }:
 
 let
+  identifier = name + "-" + version;
+  toBashArray = arr: "(" + (lib.concatStringsSep " " arr) + ")";
+
   testsAsList = lib.attrValues tests;
   checks      = builtins.map (d: haskellLib.check d) testsAsList;
 
-  identifier = name + "-" + version;
-
-  toBashArray = arr: "(" + (lib.concatStringsSep " " arr) + ")";
+  # Exclude test modules from tix file. The Main module is
+  # hard-coded here because the Main module is not listed in
+  # "$test.config.modules" (the plan.nix) but must be excluded.
+  # Note that the name of the Main module file does not matter. So
+  # a line in your cabal file such as:
+  #   main-is: Spec.hs
+  # still generates a "Main.mix" file with the contents:
+  #   Mix "Spec.hs" ...
+  # Hence we can hardcode the name "Main" here.
+  testModules = lib.foldl' (acc: test: acc ++ test.config.modules) ["Main"] testsAsList;
+
+  # Mix information HPC will need.
+  # For libraries, where we copy the mix information from differs from
+  # where HPC should look for the mix files. For tests, they are the
+  # same location.
+  mixInfo = [ { rootDir = "${library}/share/hpc/vanilla/mix";
+                searchSubDir = "${identifier}";
+              }
+            ] ++ map (drv: { rootDir = "${drv}/share/hpc/vanilla/mix"; searchSubDir = null; }) testsAsList;
+
+  mixDirs = map (info: info.rootDir) mixInfo;
+  mixSearchDirs = map (info: if info.searchSubDir == null then info.rootDir else info.rootDir + "/" + info.searchSubDir) mixInfo;
 
 in pkgs.runCommand (identifier + "-coverage-report")
   { buildInputs = (with pkgs; [ ghc ]); }
@@ -44,8 +66,6 @@ in pkgs.runCommand (identifier + "-coverage-report")
       local -n tixFs=$2
       local outFile="$3"
 
-      echo "EXCLUDED ''${excludedModules[@]}"
-      echo "EXCLUDED ''${tixFs[@]}"
       local hpcSumCmd=("hpc" "sum" "--union" "--output=$outFile")
 
       for module in "''${excludedModules[@]}"; do
@@ -60,43 +80,31 @@ in pkgs.runCommand (identifier + "-coverage-report")
       eval "''${hpcSumCmd[@]}"
     }
 
+    local mixDirs=${toBashArray mixDirs}
+
     mkdir -p $out/share/hpc/vanilla/mix/${identifier}
     mkdir -p $out/share/hpc/vanilla/tix/${identifier}
     mkdir -p $out/share/hpc/vanilla/html/${identifier}
 
-    local src=${library.src.outPath}
-    local mixDirs=${toBashArray (map (drv: "${drv}/share/hpc/vanilla/mix") ([library] ++ testsAsList))}
-    # Exclude test modules from tix file. The Main module is
-    # hard-coded here because the Main module is not listed in
-    # "$test.config.modules" (the plan.nix) but must be excluded.
-    # Note that the name of the Main module file does not matter. So
-    # a line in your cabal file such as:
-    #   main-is: Spec.hs
-    # still generates a "Main.mix" file with the contents:
-    #   Mix "Spec.hs" ...
-    # Hence we can hardcode the name "Main" here.
-    local testModules=${toBashArray (["Main"] ++ (lib.foldl' (acc: test: acc ++ test.config.modules) [] testsAsList))}
-    local totalTixFile="$out/share/hpc/vanilla/tix/${identifier}/${identifier}.tix"
-    local markupOutDir="$out/share/hpc/vanilla/html/${identifier}"
-
-    echo "''${testModules[@]}"
-
     # Copy over mix files verbatim
-    for dir in $mixDirs; do
-      if [ ! -z "$mixDir" ]; then
-        cp -R "$mixDir" $out/share/hpc/vanilla/mix/
+    for dir in "''${mixDirs[@]}"; do
+      if [ -d "$dir" ]; then
+        cp -R "$dir"/* $out/share/hpc/vanilla/mix/
       fi
     done
 
+    # Copy over tix files verbatim
     ${lib.optionalString ((builtins.length testsAsList) > 0) ''
       local tixFiles=()
       ${lib.concatStringsSep "\n" (builtins.map (check: ''
         if [ -d "${check}/share/hpc/vanilla/tix" ]; then
           pushd ${check}/share/hpc/vanilla/tix
 
           tixFile="$(find . -iwholename "*.tix" -type f -print -quit)"
+          local newTixFile=$out/share/hpc/vanilla/tix/"$tixFile"
 
-          cp "$tixFile" $out/share/hpc/vanilla/tix/
+          mkdir -p "$(dirname $newTixFile)"
+          cp "$tixFile" "$newTixFile"
 
           tixFiles+=("${check}/share/hpc/vanilla/tix/$tixFile")
 
@@ -105,10 +113,18 @@ in pkgs.runCommand (identifier + "-coverage-report")
       '') checks)
       }
 
+      # Sum tix files to create a tix file with all relevant tix
+      # information and markup a HTML report from this info.
       if (( "''${#tixFiles[@]}" > 0 )); then
-        sumTix testModules tixFiles "$totalTixFile"
-        
-        markup "$src" mixDirs testModules "$markupOutDir" "$totalTixFile"
+        local src=${library.src.outPath}
+        local mixSearchDirs=${toBashArray mixSearchDirs}
+        local testModules=${toBashArray testModules}
+        local sumTixFile="$out/share/hpc/vanilla/tix/${identifier}/${identifier}.tix"
+        local markupOutDir="$out/share/hpc/vanilla/html/${identifier}"
+
+        sumTix testModules tixFiles "$sumTixFile"
+
+        markup "$src" mixSearchDirs testModules "$markupOutDir" "$sumTixFile"
       fi
     ''}
   ''