Allow specifying the HPC data directory explicitly

- Add functionality required to allow the user to specify the hpc data
  directory explicitly, rather than searching for it in the usual
  places. This is primarily motivated by the Nix package manager,
  where hpc output is usally written to some folder outside of the
  current directory (e.g. to
  /nix/store/HASH-my-lib-0.1.0.0/share/hpc).

README.md

@@ -151,6 +151,40 @@ You will have to specify it for example when using Travis-pro as in the example
 --service-name=travis-pro
 ```
 
+#### --hpc-dir
+
+This option allows you to manually specify the hpc data directory to use. The behaviour without this option is to attempt to find the hpc directory in the typical places in the current directory.
+```bash
+--hpc-dir=/dir/share/hpc
+```
+
+This directory should contain your hpc data (mix files and tix files) in the standard directory structure for hpc output, for example:
+
+```bash
+hpc
+├── mix
+│   ├── my-lib-0.1.0.0
+│   │   └── my-lib-0.1.0.0-inplace
+│   │       ├── My.Lib.A.mix
+│   │       ├── My.Lib.B.mix
+│   |       └── My.Lib.C.mix
+│   ├── my-lib-test
+│   │   ├── SomeSpec.mix
+│   │   ├── SomeOtherSpec.mix
+│       └── Main.mix
+│   └── my-lib-test2
+│       ├── SomeSpec2.mix
+│       ├── SomeOtherSpec2.mix
+│       └── Main.mix
+└── tix
+    ├── my-lib-0.1.0.0
+    │   └── my-lib-0.1.0.0.tix
+    ├── my-lib-test
+    │   └── my-lib-test.tix
+    └── my-lib-test2
+        └── my-lib-test2.tix
+```
+
 # Limitations
 
 Because of the way hpc works, coverage data is only generated for modules that are referenced directly or indirectly by the test suites.

src/HpcCoverallsCmdLine.hs

@@ -18,6 +18,7 @@ data HpcCoverallsArgs = CmdMain
     , optCurlVerbose   :: Bool
     , optDontSend      :: Bool
     , optCoverageMode  :: CoverageMode
+    , optHpcDir        :: Maybe String
     } deriving (Data, Show, Typeable)
 
 hpcCoverallsArgs :: HpcCoverallsArgs
@@ -30,6 +31,7 @@ hpcCoverallsArgs = CmdMain
     , optCabalFile     = Nothing           &= explicit &= typ "FILE"  &= name "cabal-file"     &= help "Cabal file (ex.: module-name.cabal)"
     , optServiceName   = Nothing           &= explicit &= typ "TOKEN" &= name "service-name"   &= help "service-name (e.g. travis-pro)"
     , optRepoToken     = Nothing           &= explicit &= typ "TOKEN" &= name "repo-token"     &= help "Coveralls repo token"
+    , optHpcDir        = Nothing           &= explicit &= typDir      &= name "hpc-dir"        &= help "Explicitly use this hpc directory instead of trying to discover one"
     , argTestSuites    = []                &= typ "TEST-SUITES" &= args
     } &= summary ("hpc-coveralls v" ++ versionString version ++ ", (C) Guillaume Nargeot 2014-2015")
       &= program "hpc-coveralls"

src/HpcCoverallsMain.hs

@@ -46,6 +46,7 @@ getConfig hca = Config
     (optCabalFile hca)
     (optServiceName hca)
     (optRepoToken hca)
+    (optHpcDir hca)
     <$> listToMaybe (argTestSuites hca)
 
 main :: IO ()

src/Trace/Hpc/Coveralls.hs

@@ -19,6 +19,8 @@ import           Data.Digest.Pure.MD5
 import           Data.Function
 import           Data.List
 import qualified Data.Map.Strict as M
+import           Data.Semigroup ((<>))
+import           System.Directory (doesDirectoryExist)
 import           System.Exit (exitFailure)
 import           Trace.Hpc.Coveralls.Config
 import           Trace.Hpc.Coveralls.GitInfo (GitInfo)
@@ -137,19 +139,32 @@ generateCoverallsFromTix :: String       -- ^ CI name
                          -> Maybe String -- ^ Package name-version
                          -> IO Value     -- ^ code coverage result in json format
 generateCoverallsFromTix serviceName jobId gitInfo config mPkgNameVer = do
-    mHpcDir <- firstExistingDirectory hpcDirs
-    case mHpcDir of
-        Nothing -> putStrLn "Couldn't find the hpc data directory" >> dumpDirectory distDir >> ioFailure
-        Just hpcDir -> do
-            testSuitesCoverages <- mapM (readCoverageData mPkgNameVer hpcDir excludedDirPatterns) testSuiteNames
-            let coverageData = mergeCoverageData testSuitesCoverages
-            return $ toCoverallsJson serviceName jobId repoTokenM gitInfo converter coverageData
-            where excludedDirPatterns = excludedDirs config
-                  testSuiteNames = testSuites config
-                  repoTokenM = repoToken config
-                  converter = case coverageMode config of
-                      StrictlyFullLines -> strictConverter
-                      AllowPartialLines -> looseConverter
+    hpcDir <- findHpcDataDir config
+    testSuitesCoverages <- mapM (readCoverageData mPkgNameVer hpcDir excludedDirPatterns) testSuiteNames
+    let coverageData = mergeCoverageData testSuitesCoverages
+    return $ toCoverallsJson serviceName jobId repoTokenM gitInfo converter coverageData
+    where excludedDirPatterns = excludedDirs config
+          testSuiteNames = testSuites config
+          repoTokenM = repoToken config
+          converter = case coverageMode config of
+              StrictlyFullLines -> strictConverter
+              AllowPartialLines -> looseConverter
+
+findHpcDataDir :: Config -> IO FilePath
+findHpcDataDir config = do
+  case hpcDirOverride config of
+    Nothing -> do
+      mHpcDir <- firstExistingDirectory hpcDirs
+      case mHpcDir of
+        Nothing     -> putStrLn "Couldn't find the hpc data directory" >> dumpDirectory distDir >> ioFailure
+        Just hpcDir -> pure hpcDir
+    Just hpcDirOverride -> do
+      let hpcDir = hpcDirOverride <> "/"
+      doesExist <- doesDirectoryExist hpcDir
+      if doesExist == False
+        then putStrLn ("The hpc data directory override provided does not exist: " <> hpcDir) >> ioFailure
+        else pure hpcDir
+
 
 ioFailure :: IO a
 ioFailure = putStrLn ("You can get support at " ++ gitterUrl) >> exitFailure

src/Trace/Hpc/Coveralls/Cabal.hs

@@ -23,11 +23,16 @@ import System.Directory
 
 getCabalFile :: FilePath -> IO (Maybe FilePath)
 getCabalFile dir = do
-    files <- (filter isCabal <$> getDirectoryContents dir) >>= filterM doesFileExist
-    case files of
-        [file] -> return $ Just file
-        _ -> return Nothing
-    where isCabal filename = ".cabal" `isSuffixOf` filename && length filename > 6
+    cabalFilesInDir <- filter isCabal <$> getDirectoryContents dir
+    cabalFiles <- filterM doesFileExist (mkFullPath <$> cabalFilesInDir)
+    case cabalFiles of
+        [file] -> do
+          return $ Just file
+        _ -> do
+          return Nothing
+    where
+      isCabal filename = ".cabal" `isSuffixOf` filename && length filename > 6
+      mkFullPath = ((dir <> "/") <>)
 
 getPackageNameVersion :: FilePath -> IO (Maybe String)
 getPackageNameVersion file = do

src/Trace/Hpc/Coveralls/Config.hs

@@ -3,10 +3,11 @@ module Trace.Hpc.Coveralls.Config where
 import Trace.Hpc.Coveralls.Types (CoverageMode)
 
 data Config = Config {
-    excludedDirs :: ![FilePath],
-    coverageMode :: !CoverageMode,
-    cabalFile    :: !(Maybe FilePath),
-    serviceName  :: !(Maybe String),
-    repoToken    :: !(Maybe String),
-    testSuites   :: ![String]
+    excludedDirs   :: ![FilePath],
+    coverageMode   :: !CoverageMode,
+    cabalFile      :: !(Maybe FilePath),
+    serviceName    :: !(Maybe String),
+    repoToken      :: !(Maybe String),
+    hpcDirOverride :: !(Maybe String),
+    testSuites     :: ![String]
     }