Document and test encode/decodeModule.

See #197, #210.

src/Base.hs

@@ -98,13 +98,16 @@ versionToInt s = major * 1000 + minor * 10 + patch
 
 -- | Given a module name extract the directory and file name, e.g.:
 --
--- > decodeModule "Data.Functor.Identity" = ("Data/Functor/", "Identity")
+-- > decodeModule "Data.Functor.Identity" == ("Data/Functor/", "Identity")
+-- > decodeModule "Prelude"               == ("./", "Prelude")
 decodeModule :: String -> (FilePath, String)
 decodeModule = splitFileName . replaceEq '.' '/'
 
 -- | Given the directory and file name find the corresponding module name, e.g.:
 --
--- > encodeModule "Data/Functor/" "Identity.hs" = "Data.Functor.Identity"
+-- > encodeModule "Data/Functor/" "Identity.hs" == "Data.Functor.Identity"
+-- > encodeModule "./" "Prelude"                == "Prelude"
+-- > uncurry encodeModule (decodeModule name)   == name
 encodeModule :: FilePath -> String -> String
 encodeModule dir file = replaceEq '/' '.' $ dir -/- takeBaseName file
 

src/Rules/Selftest.hs

@@ -24,6 +24,7 @@ selftestRules =
         testWays
         testChunksOfSize
         testMatchVersionedFilePath
+        testModuleNames
 
 testWays :: Action ()
 testWays = do
@@ -54,3 +55,16 @@ testMatchVersionedFilePath = do
         matchVersionedFilePath prefix suffix (prefix ++ version ++ suffix)
   where
     versions = listOf . elements $ '-' : '.' : ['0'..'9']
+
+testModuleNames :: Action ()
+testModuleNames = do
+    putBuild $ "==== Encode/decode module name"
+    test $ encodeModule "Data/Functor/" "Identity.hs" == "Data.Functor.Identity"
+    test $ encodeModule "./" "Prelude"                == "Prelude"
+
+    test $ decodeModule "Data.Functor.Identity" == ("Data/Functor/", "Identity")
+    test $ decodeModule "Prelude"               == ("./", "Prelude")
+
+    test $ forAll names $ \n -> uncurry encodeModule (decodeModule n) == n
+  where
+    names = intercalate "." <$> listOf1 (listOf1 $ elements "abcABC123_'")