Return empty default when git fails

Add maybe in guess functions

Adjust type in NonInteractive

Change unit tests

Fix whitespace

Abstract guessing and remove comments

Simplify guess functions

Return default for cabal init author and name when git fails

cabal-install/src/Distribution/Client/Init/Interactive/Command.hs

@@ -355,14 +355,10 @@ licensePrompt flags = getLicense flags $ do
       else fmap prettyShow knownLicenses
 
 authorPrompt :: Interactive m => InitFlags -> m String
-authorPrompt flags = getAuthor flags $ do
-    name <- guessAuthorName
-    promptStr "Author name" (DefaultPrompt name)
+authorPrompt flags = getAuthor flags $ guessAuthorName >>= promptOrDefault "Author name"
 
 emailPrompt :: Interactive m => InitFlags -> m String
-emailPrompt flags = getEmail flags $ do
-    email' <- guessAuthorEmail
-    promptStr "Maintainer email" (DefaultPrompt email')
+emailPrompt flags = getEmail flags $ guessAuthorEmail >>= promptOrDefault "Maintainer email"
 
 homepagePrompt :: Interactive m => InitFlags -> m String
 homepagePrompt flags = getHomepage flags $
@@ -467,3 +463,6 @@ srcDirsPrompt flags = getSrcDirs flags $ do
       True
 
     return [dir]
+
+promptOrDefault :: Interactive m => String -> Maybe String -> m String
+promptOrDefault s = maybe (promptStr s MandatoryPrompt)  (promptStr s . DefaultPrompt)

cabal-install/src/Distribution/Client/Init/NonInteractive/Command.hs

@@ -274,14 +274,16 @@ licenseHeuristics :: Interactive m => InitFlags -> m SpecLicense
 licenseHeuristics flags = getLicense flags $ guessLicense flags
 
 -- | The author's name. Prompt, or try to guess from an existing
---   darcs repo.
+--   git repo.
 authorHeuristics :: Interactive m => InitFlags -> m String
-authorHeuristics flags = getAuthor flags guessAuthorEmail
+authorHeuristics flags = guessAuthorEmail >>=
+  maybe (getAuthor flags $ return "") (getAuthor flags . return)
 
 -- | The author's email. Prompt, or try to guess from an existing
---   darcs repo.
+--   git repo.
 emailHeuristics :: Interactive m => InitFlags -> m String
-emailHeuristics flags = getEmail flags guessAuthorName
+emailHeuristics flags = guessAuthorName >>=
+  maybe (getEmail flags $ return "") (getEmail flags . return)
 
 -- | Prompt for a homepage URL for the package.
 homepageHeuristics :: Interactive m => InitFlags -> m String

cabal-install/src/Distribution/Client/Init/NonInteractive/Heuristics.hs

@@ -151,18 +151,23 @@ guessSourceDirectories flags = do
     True  -> ["src"]
 
 -- | Guess author and email using git configuration options.
-guessAuthorName :: Interactive m => m String
+guessAuthorName :: Interactive m => m (Maybe String)
 guessAuthorName = guessGitInfo "user.name"
 
-guessAuthorEmail :: Interactive m => m String
+guessAuthorEmail :: Interactive m => m (Maybe String)
 guessAuthorEmail = guessGitInfo "user.email"
 
-guessGitInfo :: Interactive m => String -> m String
+guessGitInfo :: Interactive m => String -> m (Maybe String)
 guessGitInfo target = do
-  info <- readProcessWithExitCode "git" ["config", "--local", target] ""
-  if null $ snd' info
-    then trim . snd' <$> readProcessWithExitCode "git" ["config", "--global", target] ""
-    else return . trim $ snd' info
+  localInfo <- readProcessWithExitCode "git" ["config", "--local", target] ""
+  if null $ snd' localInfo
+    then do
+      globalInfo <- readProcessWithExitCode "git" ["config", "--global", target] ""
+      case fst' globalInfo of
+        ExitSuccess -> return $  Just (trim $ snd' globalInfo)
+        _           -> return Nothing
+    else return $  Just (trim $ snd' localInfo)
 
   where
+    fst' (x, _, _) = x
     snd' (_, x, _) = x

cabal-install/tests/UnitTests/Distribution/Client/Init/FileCreators.hs

@@ -44,7 +44,9 @@ tests _v _initFlags comp pkgIx srcDb =
               }
             inputs =
               -- createProject stuff
-              [ "True"
+              [ "Foobar"
+              , "foobar@qux.com"
+              , "True"
               , "[\"quxTest/Main.hs\"]"
               -- writeProject stuff
               -- writeLicense

cabal-install/tests/UnitTests/Distribution/Client/Init/NonInteractive.hs

@@ -73,7 +73,9 @@ driverFunctionTest pkgIx srcDb comp = testGroup "createProject"
               , dependencies = Flag []
               }
             inputs = NEL.fromList
-              [ "True"
+              ["Foobar"
+              , "foobar@qux.com"
+              , "True"
               , "[\"quxTest/Main.hs\"]"
               ]
 
@@ -149,8 +151,11 @@ driverFunctionTest pkgIx srcDb comp = testGroup "createProject"
               , dependencies = Flag []
               }
             inputs = NEL.fromList
+
+              [ "Foobar"
+              , "foobar@qux.com"
               -- extra sources
-              [ "[\"CHANGELOG.md\"]"
+              , "[\"CHANGELOG.md\"]"
               -- lib other modules
               , "False"
               -- exe other modules