[#90] Forbid verifying a single file

Problem: Verifying a single file using `-r` option missbehaves
when there are absolute links present in the file. Since `-r`
option expects a directory, we can just forbid verifying a single
file.

Solution: Fail with an error message when the user tries to
specify a file as the repository's root directory.

CHANGES.md

@@ -6,6 +6,8 @@
 
 Unreleased
 ==========
+* [#117](https://github.com/serokell/xrefcheck/pull/117)
+  + Forbid verifying a single file using `--root` command line option.
 * [#115](https://github.com/serokell/xrefcheck/pull/115)
   + Improved parsing of anchor html tags inside headers.
 * [#109](https://github.com/serokell/xrefcheck/pull/109)

src/Xrefcheck/Scan.hs

@@ -23,11 +23,13 @@ import Data.Aeson.TH (deriveFromJSON)
 import Data.Foldable qualified as F
 import Data.Map qualified as M
 import GHC.Err (errorWithoutStackTrace)
+import System.Directory (doesDirectoryExist)
 import System.Directory.Tree qualified as Tree
 import System.FilePath (dropTrailingPathSeparator, takeDirectory, takeExtension, (</>), equalFilePath)
 
 import Xrefcheck.Core
 import Xrefcheck.Progress
+import Xrefcheck.System (readingSystem)
 import Xrefcheck.Util (aesonConfigOption, normaliseWithNoTrailing)
 
 -- | Config of repositry traversal.
@@ -64,6 +66,10 @@ gatherRepoInfo
   => Rewrite -> FormatsSupport -> TraversalConfig -> FilePath -> m RepoInfo
 gatherRepoInfo rw formatsSupport config root = do
   putTextRewrite rw "Scanning repository..."
+
+  when (not $ isDirectory root) $
+    die $ "Repository's root does not seem to be a directory: " <> root
+
   _ Tree.:/ repoTree <- liftIO $ Tree.readDirectoryWithL processFile root
   let fileInfos = map (first normaliseWithNoTrailing)
         $ filter (\(path, _) -> not $ isIgnored path)
@@ -72,6 +78,8 @@ gatherRepoInfo rw formatsSupport config root = do
         $ filterExcludedDirs root repoTree
   return $ RepoInfo (M.fromList fileInfos)
   where
+    isDirectory = readingSystem . doesDirectoryExist
+
     processFile file = do
       let ext = takeExtension file
       let mscanner = formatsSupport ext

tests/Test/Xrefcheck/TrailingSlashSpec.hs

@@ -45,6 +45,4 @@ spec = do
       [ "tests/markdowns/without-annotations"
       , "tests/markdowns/without-annotations/"
       , "tests/markdowns/without-annotations/./"
-      , "tests/markdowns/without-annotations/all_checked.md"
-      , "tests/markdowns/without-annotations/./all_checked.md"
       ]

tests/golden/check-cli/check-cli.bats

@@ -77,3 +77,11 @@ load '../helpers'
 
   rm /tmp/check-cli.test
 }
+
+@test "Single file as root" {
+  run xrefcheck \
+    --root single-file.md
+
+  assert_failure
+  assert_output --partial "Repository's root does not seem to be a directory: single-file.md"
+}