Checks for duplicate FileDraft _dstPath during generation (#733)

waspc/src/Wasp/Generator/WriteFileDrafts.hs

@@ -3,6 +3,7 @@
 module Wasp.Generator.WriteFileDrafts
   ( synchronizeFileDraftsWithDisk,
     fileDraftsToWriteAndFilesToDelete, -- Exported for testing.
+    assertDstPathsAreUnique, -- Exported for testing.
     removeFromChecksumFile,
   )
 where
@@ -15,7 +16,7 @@ import qualified Data.ByteString.Lazy as BSL
 import Data.Either (lefts, rights)
 import qualified Data.HashMap.Strict as Map
 import qualified Data.HashSet as Set
-import Data.List (sortBy)
+import Data.List (group, sort, sortBy)
 import StrongPath (Abs, Dir, File', Path', Rel, relfile, (</>))
 import qualified StrongPath as SP
 import System.Directory (removeDirectoryRecursive, removeFile)
@@ -31,6 +32,8 @@ import Wasp.Util (Checksum)
 -- It is smart when writing, so it doesn't write file drafts that are already written on the disk from before.
 synchronizeFileDraftsWithDisk :: Path' Abs (Dir ProjectRootDir) -> [FileDraft] -> IO ()
 synchronizeFileDraftsWithDisk dstDir fileDrafts = do
+  return $! assertDstPathsAreUnique fileDrafts
+
   maybePathsToChecksums <- readChecksumFile dstDir
   case maybePathsToChecksums of
     -- If checksums file is missing/corrupted, we delete all of the generated code
@@ -60,6 +63,14 @@ type RelPathsToChecksums = [(FileOrDirPathRelativeTo ProjectRootDir, Checksum)]
 
 type RelPathsToChecksumsMap = Map.HashMap (FileOrDirPathRelativeTo ProjectRootDir) Checksum
 
+-- | Takes file drafts and verifies if the destination paths are unique.
+assertDstPathsAreUnique :: [FileDraft] -> ()
+assertDstPathsAreUnique fileDrafts =
+  let fdDstPaths = map getDstPath fileDrafts
+      duplicateFdDstPaths = map head $ filter ((> 1) . length) (group . sort $ fdDstPaths)
+      errMessage = unlines $ "FileDraft destination paths are not unique! Duplicates include: " : map show duplicateFdDstPaths
+   in if null duplicateFdDstPaths then () else error errMessage
+
 -- | This file stores all checksums for files and directories that were written to disk
 -- on the last project generation.
 checksumFileInProjectRoot :: Path' (Rel ProjectRootDir) File'

waspc/test/Generator/WriteFileDraftsTest.hs

@@ -4,11 +4,11 @@ import Data.Bifunctor (Bifunctor (first))
 import Data.Maybe (fromJust)
 import Data.Text (pack)
 import qualified StrongPath as SP
-import Test.Tasty.Hspec (Spec, describe, it, shouldBe, shouldMatchList)
+import Test.Tasty.Hspec (Spec, anyErrorCall, describe, it, shouldBe, shouldMatchList, shouldReturn, shouldThrow)
 import Wasp.Generator.FileDraft (FileDraft (FileDraftTextFd), Writeable (getDstPath))
 import Wasp.Generator.FileDraft.TextFileDraft (TextFileDraft)
 import qualified Wasp.Generator.FileDraft.TextFileDraft as TextFD
-import Wasp.Generator.WriteFileDrafts (fileDraftsToWriteAndFilesToDelete)
+import Wasp.Generator.WriteFileDrafts (assertDstPathsAreUnique, fileDraftsToWriteAndFilesToDelete)
 import Wasp.Util (Checksum, checksumFromString, checksumFromText)
 
 genMockTextFileDrafts :: Int -> [TextFileDraft]
@@ -24,6 +24,16 @@ genFdsWithChecksums :: Int -> [(FileDraft, Checksum)]
 genFdsWithChecksums n =
   map (\fd -> (FileDraftTextFd fd, checksumFromText $ TextFD._content fd)) (genMockTextFileDrafts n)
 
+spec_WriteDuplicatedDstFileDrafts :: Spec
+spec_WriteDuplicatedDstFileDrafts =
+  describe "fileDraftsWithDuplicatedDstPaths" $ do
+    it "should throw error since there are duplicated destination paths" $
+      let fileDrafts = replicate 2 $ FileDraftTextFd $ head (genMockTextFileDrafts 1)
+       in (return $! assertDstPathsAreUnique fileDrafts) `shouldThrow` anyErrorCall
+    it "should not throw error because unique destination paths" $
+      let fileDrafts = map FileDraftTextFd (genMockTextFileDrafts 2)
+       in (return $! assertDstPathsAreUnique fileDrafts) `shouldReturn` ()
+
 spec_WriteFileDrafts :: Spec
 spec_WriteFileDrafts =
   describe "fileDraftsToWriteAndFilesToDelete" $ do