From d0bd687a23672fd420fdb25eb11824d1741ff1d8 Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Tue, 17 Dec 2024 09:27:14 -0500
Subject: [PATCH 1/4] Use OS-specific splitPath before comparing projects

- Manually replace path separators before anything else
- Use pathSeparator instead of literal char
- Use isPathSeparator predicate
---
 .../Solver/Types/ProjectConfigPath.hs         | 26 +++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs b/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
index a1709a0cf9f..17543b5f2de 100644
--- a/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
+++ b/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
@@ -32,13 +32,17 @@ import Data.Coerce (coerce)
 import Data.List.NonEmpty ((<|))
 import Network.URI (parseURI, parseAbsoluteURI)
 import System.Directory
-import System.FilePath
+import System.FilePath hiding (splitPath)
+import qualified System.FilePath as FP (splitPath)
+import qualified System.FilePath.Posix as Posix
+import qualified System.FilePath.Windows as Windows
 import qualified Data.List.NonEmpty as NE
 import Distribution.Solver.Modular.Version (VR)
 import Distribution.Pretty (prettyShow)
 import Distribution.Utils.String (trim)
 import Text.PrettyPrint
 import Distribution.Simple.Utils (ordNub)
+import Distribution.System (OS(Windows), buildOS)
 
 -- | Path to a configuration file, either a singleton project root, or a longer
 -- list representing a path to an import.  The path is a non-empty list that we
@@ -61,6 +65,14 @@ newtype ProjectConfigPath = ProjectConfigPath (NonEmpty FilePath)
 -- The project itself, a single element root path, compared to any of the
 -- configuration paths it imports, should always sort first. Comparing one
 -- project root path against another is done lexically.
+--
+-- For comparison purposes, path separators are normalized to the @buildOS@
+-- platform's path separator.
+--
+-- >>> let abFwd = ProjectConfigPath $ "a/b.config" :| []
+-- >>> let abBwd = ProjectConfigPath $ "a\\b.config" :| []
+-- >>> compare abFwd abBwd
+-- EQ
 instance Ord ProjectConfigPath where
     compare pa@(ProjectConfigPath (NE.toList -> as)) pb@(ProjectConfigPath (NE.toList -> bs)) =
         case (as, bs) of
@@ -69,7 +81,7 @@ instance Ord ProjectConfigPath where
             -- this though, do a comparison anyway when both sides have length
             -- 1.  The root path, the project itself, should always be the first
             -- path in a sorted listing.
-            ([a], [b]) -> compare a b
+            ([a], [b]) -> compare (splitPath a) (splitPath b)
             ([_], _) -> LT
             (_, [_]) -> GT
 
@@ -83,6 +95,16 @@ instance Ord ProjectConfigPath where
                 P.<> compare (length aPaths) (length bPaths)
                 P.<> compare aPaths bPaths
         where
+            splitPath = FP.splitPath . normSep where
+                normSep p =
+                    if buildOS == Windows
+                        then
+                            Windows.joinPath $ Windows.splitDirectories
+                            [if Posix.isPathSeparator c then Windows.pathSeparator else c| c <- p]
+                        else
+                            Posix.joinPath $ Posix.splitDirectories
+                            [if Windows.isPathSeparator c then Posix.pathSeparator else c| c <- p]
+
             aPaths = splitPath <$> as
             bPaths = splitPath <$> bs
             aImporters = snd $ unconsProjectConfigPath pa

From 30f5d3f2162ce36ae63527de9d08efdc6a4f5647 Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Wed, 1 Jan 2025 08:05:12 -0500
Subject: [PATCH 2/4] Needle in haystack multiline expectations

- Add else.project test
- Use normalizeWindowsOutput
- Add a changelog entry
- Update expectation
- Use concatOutput on needle
- Include output
- Align lines
- Show modified output
- Apply concatOutput to the needle
- Show start and end of lines with ASCII ^ and $h
- Can't print pilcrow so use grep char for marking end of line
- Marking the start of line distinguishes "expected" intro from its content too, same for "output"
- Use \n in multiline string expectation
- Add NeedleHaystack
- Add expectNeedleInHaystack field to NeedleHaystack
- Remove 3 assert*Contains functions
- Add TxContains record
- Apply the txBwd transformations before display
- Add displayHaystack field
- Switch to using <EOL> as the marker
- Sort language pragmas
- Use ++ rather than cons with reversals
- Rerun ParseErrorProvenance test
- Add doctests for single line strings
- Read exected multiline string from file
- Use lineBreaksToSpaces
- Add module Test.Cabal.NeedleHaystack
- Redo ConditionalAndImport with multiline expectations
- Add test of string expectation start and end marking
- Rename encodeLf and decodeLfMarkLines
- Rename original concatOutput to lineBreaksToSpaces
- Add assertOutputContainsWrapped
- Use multiline and wrapped assertions
- DedupUsingConfigFromComplex multiline assertion
- Remove redundant tests that fail on Windows
- Use normalizeWindowsOutput in ConditionalAndImport
- Forward conversion applied twice by mistake
- Easier diff when assertOn follows assertOutputContains
- Add readVerbatimFile
- Have readVerbatimFile read contents strictly
- Add normalizePathSeparator
- Don't modify path separator for URIs
- Don't normalize path with anything URI-like
- Normalize expected output
- Rename to normalizePathSeparators
- Add an explicit export list to NeedleHaystack
- Drop unlines . lines added trailing newline
- Show example of normalizePathSeparators
- Use local unsnoc definition to avoid CPP
- Define local unlines
- Satisfy fix-whitespace
- Don't use <EOL>
- Rename to delimitLines
- Rename the changelog with *.md extension
- Add a section on cabal-testsuite changes
- Rename the function to readFileVerbatim
- Add to contributing and cabal-testsuite's readme
- Use setup for the noun
- Typo s/displaying/display
- Typo "can easier"
- Use unsnoc from Cabal-syntax Utils.Generic
- Add a note [Multiline Needles]
- Remove doctests available elsewhere
- Substitute encodeLf for concatOutput for assertOutputMatches
---
 CONTRIBUTING.md                               |   9 +-
 .../ParseErrorProvenance/cabal.out            |  10 +
 .../ParseErrorProvenance/cabal.test.hs        |  24 ++
 .../ParseErrorProvenance/dir-else/else.config |   4 +
 .../ParseErrorProvenance/else.project         |   1 +
 .../ParseErrorProvenance/msg.expect.txt       |   5 +
 cabal-testsuite/README.md                     |   4 +
 cabal-testsuite/cabal-testsuite.cabal         |   2 +
 .../src/Test/Cabal/NeedleHaystack.hs          | 277 ++++++++++++++++++
 cabal-testsuite/src/Test/Cabal/Prelude.hs     |  80 +++--
 changelog.d/pr-10646.md                       | 209 +++++++++++++
 11 files changed, 604 insertions(+), 21 deletions(-)
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/dir-else/else.config
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/else.project
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/msg.expect.txt
 create mode 100644 cabal-testsuite/src/Test/Cabal/NeedleHaystack.hs
 create mode 100644 changelog.d/pr-10646.md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 81ea71849da..7a7842017c5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -395,9 +395,12 @@ description: {
 }
 ```
 
-Changelogs may also be written in "markdown-frontmatter" format. This is useful if your
-description contains braces, which must be escaped with backslashes in `.cabal` file
-format. The front matter is in YAML syntax, not `.cabal` file syntax, and the file
+Changelogs may also be written in "markdown-frontmatter" format. This is useful
+if your description contains braces, which must be escaped with backslashes in
+`.cabal` file format. Another benefit of using an `.md` extension with your
+changelog is that it will be checked for typos.
+
+The front matter is in YAML syntax, not `.cabal` file syntax, and the file
 _must_ begin with a line containing only hyphens.
 
 ```markdown
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
new file mode 100644
index 00000000000..a3143ff9ffd
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
@@ -0,0 +1,10 @@
+# cabal v2-build
+Warning: <ROOT>/else.project, else.project: Unrecognized section '_' on line 3
+# Multiline string marking:
+# ^When using configuration from:$
+# ^  - else.project$
+# ^  - dir-else/else.config$
+# ^The following errors occurred:$
+# ^  - The package location 'no-pkg-here' does not exist.$
+# Pseudo multiline string marking:
+# ^When using configuration from:   - else.project   - dir-else/else.config The following errors occurred:   - The package location 'no-pkg-here' does not exist.$
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
new file mode 100644
index 00000000000..49360b59872
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
@@ -0,0 +1,24 @@
+import Test.Cabal.Prelude
+import System.Directory
+
+main = cabalTest . recordMode RecordMarked $ do
+  let log = recordHeader . pure
+
+  outElse <- fails $ cabal' "v2-build" [ "all", "--dry-run", "--project-file=else.project" ]
+
+  msg <- readFileVerbatim "msg.expect.txt"
+  let msgSingle = lineBreaksToSpaces msg
+
+  log "Multiline string marking:"
+  mapM_ log (lines . delimitLines $ encodeLf msg)
+
+  log "Pseudo multiline string marking:"
+  mapM_ log (lines . delimitLines $ encodeLf msgSingle)
+
+  assertOn multilineNeedleHaystack msg outElse
+  assertOn multilineNeedleHaystack{expectNeedleInHaystack = False} msgSingle outElse
+
+  assertOutputContains msg outElse
+  assertOutputDoesNotContain msgSingle outElse
+
+  return ()
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/dir-else/else.config b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/dir-else/else.config
new file mode 100644
index 00000000000..f9c44e63d5b
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/dir-else/else.config
@@ -0,0 +1,4 @@
+if false
+else
+    _
+    packages: no-pkg-here
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/else.project b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/else.project
new file mode 100644
index 00000000000..959c40f5660
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/else.project
@@ -0,0 +1 @@
+import: dir-else/else.config
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/msg.expect.txt b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/msg.expect.txt
new file mode 100644
index 00000000000..e5291b3adcd
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/msg.expect.txt
@@ -0,0 +1,5 @@
+When using configuration from:
+  - else.project
+  - dir-else/else.config
+The following errors occurred:
+  - The package location 'no-pkg-here' does not exist.
diff --git a/cabal-testsuite/README.md b/cabal-testsuite/README.md
index 2c3d17e6150..fb641cad995 100644
--- a/cabal-testsuite/README.md
+++ b/cabal-testsuite/README.md
@@ -218,6 +218,10 @@ variants of a command (e.g., `cabal'` rather than `cabal`) and use
 `assertOutputContains`.  Note that this will search over BOTH stdout
 and stderr.
 
+For convenience, paste expected multiline string values verbatim into a text
+file and read these with `readFileVerbatim`. The suggested extension for these
+files are `.expect.txt`.
+
 **How do I skip running a test in some environments?**  Use the
 `skipIf` and `skipUnless` combinators.  Useful parameters to test
 these with include `hasSharedLibraries`, `hasProfiledLibraries`,
diff --git a/cabal-testsuite/cabal-testsuite.cabal b/cabal-testsuite/cabal-testsuite.cabal
index 0f3383af38a..4e31b87d254 100644
--- a/cabal-testsuite/cabal-testsuite.cabal
+++ b/cabal-testsuite/cabal-testsuite.cabal
@@ -45,6 +45,7 @@ library
     Test.Cabal.CheckArMetadata
     Test.Cabal.DecodeShowBuildInfo
     Test.Cabal.Monad
+    Test.Cabal.NeedleHaystack
     Test.Cabal.OutputNormalizer
     Test.Cabal.Plan
     Test.Cabal.Prelude
@@ -71,6 +72,7 @@ library
     , exceptions            ^>= 0.10.0
     , filepath              ^>= 1.3.0.1 || ^>= 1.4.0.0 || ^>= 1.5.0.0
     , Glob                  ^>= 0.10.2
+    , network-uri            >= 2.6.0.2 && < 2.7
     , network-wait          ^>= 0.1.2.0 || ^>= 0.2.0.0
     , optparse-applicative  ^>= 0.14.3.0 || ^>=0.15.1.0 || ^>=0.16.0.0 || ^>= 0.17.0.0 || ^>= 0.18.1.0
     , process               ^>= 1.2.1.0 || ^>= 1.4.2.0 || ^>= 1.6.1.0
diff --git a/cabal-testsuite/src/Test/Cabal/NeedleHaystack.hs b/cabal-testsuite/src/Test/Cabal/NeedleHaystack.hs
new file mode 100644
index 00000000000..42ab1031284
--- /dev/null
+++ b/cabal-testsuite/src/Test/Cabal/NeedleHaystack.hs
@@ -0,0 +1,277 @@
+{-# LANGUAGE MultiWayIf #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE ViewPatterns #-}
+
+-- | Functions for searching for a needle in a haystack, with transformations
+-- for the strings to search in and the search strings such as re-encoding line
+-- breaks or delimiting lines. Both LF and CRLF line breaks are recognized.
+module Test.Cabal.NeedleHaystack
+    ( TxContains(..)
+    , txContainsId
+    , NeedleHaystack(..)
+    , symNeedleHaystack
+    , multilineNeedleHaystack
+    , needleHaystack
+    , lineBreaksToSpaces
+    , normalizePathSeparators
+    , encodeLf
+    , delimitLines
+    ) where
+
+import Prelude hiding (unlines)
+import qualified Prelude (unlines)
+import Data.List (tails)
+import Data.Maybe (isJust)
+import Distribution.System
+import Distribution.Utils.Generic (unsnoc)
+import Data.List (isPrefixOf)
+import qualified System.FilePath.Posix as Posix
+import qualified System.FilePath.Windows as Windows
+import Network.URI (parseURI)
+
+{-
+Note [Multiline Needles]
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+How we search for multiline strings in output that varies by platform.
+
+Reading Expected Multiline Strings Verbatim
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+With @ghc-9.12.1@ adding @-XMultilineStrings@, writing multiline string
+expectations for @cabal-testsuite/PackageTests/**/*.test.hs@ test scripts might
+be have been easier but for a catch. We run these tests with older @GHC@
+versions so would need to use @-XCPP@ for those versions and the C preprocessor
+does not play nicely with string gaps. While it is possible to encode a
+multiline string as a single line with embedded LF characters or by breaking the
+line up arbitrarily and using @++@ concatenation or by calling unlines on a list
+of lines, string gaps are the multiline strings of Haskell prior to
+@-XMultilineStrings@.
+
+To avoid these problems and for the convenience of pasting the expected value
+verbatim into a file, @readFileVerbatim@ can read the expected multiline output
+for tests from a text file.  This has the same implementation as @readFile@ from
+the @strict-io@ package to avoid problems at cleanup.
+
+Warning: Windows file locking hack: hit the retry limit 3 while trying to remove
+C:\Users\<username>\AppData\Local\Temp\cabal-testsuite-8376
+cabal.test.hs:
+C:\Users\<username>\AppData\Local\Temp\cabal-testsuite-8376\errors.expect.txt: removePathForcibly:DeleteFile
+"\\\\?\\C:\\Users\\<username>\\AppData\\Local\\Temp\\cabal-testsuite-8376\\errors.expect.txt":
+permission denied (The process cannot access the file because it is being used by another process.)
+
+The other process accessing the file is @C:\WINDOWS\System32\svchost.exe@
+running a @QueryDirectory@ event and this problem only occurs when the test
+fails.
+
+Hidden Actual Value Modification
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The @assertOutputContains@ function was modifying the actual value (the test
+output) with @concatOutput@ before checking if it contained the expected value.
+This function, now renamed as @lineBreaksToSpaces@, would remove CR values and
+convert LF values to spaces.
+
+With this setup, false positives were possible. An expected value using string
+gaps and spaces would match a @concatOutput@ modified actual value of
+"foo_bar_baz", where '_' was any of space, LF or CRLF in the unmodified actual
+value. The latter two are false positive matches.
+
+> let expect = "foo \
+>              \bar \
+>              \baz"
+
+False negatives were also possible. An expected value set up using string gaps
+with LF characters or with @-XMultilineStrings@ wouldn't match an actual value
+of "foo_bar_baz", where '_' was either LF or CRLF because these characters had
+been replaced by spaces in the actual value, modified before the comparison.
+
+> let expect = "foo\n\
+>              \bar\n\
+>              \baz"
+
+> {-# LANGUAGE MultilineStrings #-}
+>
+> let expect = """
+>              foo
+>              bar
+>              baz
+>              """
+
+We had these problems:
+
+1. The actual value was changed before comparison and this change was not visible.
+2. The expected value was not changed in the same way as the actual value. This
+   made it possible for equal values to become unequal (false negatives) and for
+   unequal values to become equal (false positives).
+
+Explicit Changes and Visible Line Delimiters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To fix these problems, an added @assertOn@ function takes a @NeedleHaystack@
+configuration for how the search is made, what to expect (to find the expected
+value or not) and how to display the expected and actual values.
+
+A pilcrow ¶ is often used to visibly display line endings but our terminal
+output is restricted to ASCII so lines are delimited between @^@ and @$@
+markers. The needle (the expected output fragment) is shown annotated this way
+and the haystack (the actual output) can optionally be shown this way too.
+
+This is still a lenient match, allowing LF to match CRLF, but @encodeLf@ doesn't
+replace LF with spaces like @concatOutput@ (@lineBreaksToSpaces@) did:
+
+If you choose to display the actual value by setting
+@NeedleHaystack{displayHaystack = True}@ then its lines will be delimited.
+
+With @assertOn@, supplying string transformation to both the needle and haystack
+before comparison and before display can help find out why an expected value is
+or isn't found in the test output.
+-}
+
+-- | Transformations for the search strings and the text to search in.
+data TxContains =
+    TxContains
+        {
+            -- | Reverse conversion for display, applied to the forward converted value.
+            txBwd :: (String -> String),
+            -- | Forward conversion for comparison.
+            txFwd :: (String -> String)
+        }
+
+-- | Identity transformation for the search strings and the text to search in,
+-- leaves them unchanged.
+txContainsId :: TxContains
+txContainsId = TxContains id id
+
+-- | Conversions of the needle and haystack strings, the seach string and the
+-- text to search in.
+data NeedleHaystack =
+    NeedleHaystack
+        {
+            expectNeedleInHaystack :: Bool,
+            displayHaystack :: Bool,
+            txNeedle :: TxContains,
+            txHaystack :: TxContains
+        }
+
+-- | Symmetric needle and haystack functions, the same conversion for each going
+-- forward and the same coversion for each going backward.
+symNeedleHaystack :: (String -> String) -> (String -> String) -> NeedleHaystack
+symNeedleHaystack bwd fwd = let tx = TxContains bwd fwd in NeedleHaystack True False tx tx
+
+-- | Multiline needle and haystack functions with symmetric conversions. Going
+-- forward converts line breaks to @"\\n"@.  Going backward adds visible
+-- delimiters to lines.
+multilineNeedleHaystack :: NeedleHaystack
+multilineNeedleHaystack = symNeedleHaystack delimitLines encodeLf
+
+-- | Minimal set up for finding the needle in the haystack. Doesn't change the
+-- strings and doesn't display the haystack in any assertion failure message.
+needleHaystack :: NeedleHaystack
+needleHaystack = NeedleHaystack True False txContainsId txContainsId
+
+-- | Replace line breaks with spaces, correctly handling @"\\r\\n"@.
+--
+-- >>> lineBreaksToSpaces "foo\nbar\r\nbaz"
+-- "foo bar baz"
+--
+-- >>> lineBreaksToSpaces "foo\nbar\r\nbaz\n"
+-- "foo bar baz"
+--
+-- >>> lineBreaksToSpaces "\nfoo\nbar\r\nbaz\n"
+-- " foo bar baz"
+lineBreaksToSpaces :: String -> String
+lineBreaksToSpaces = unwords . lines . filter ((/=) '\r')
+
+-- | Replaces path separators found with those of the current OS, URL-like paths
+-- excluded.
+--
+-- > buildOS == Linux; normalizePathSeparators "foo\bar\baz" => "foo/bar/baz"
+-- > buildOS == Windows; normalizePathSeparators "foo/bar/baz" => "foo\bar\baz"
+normalizePathSeparators :: String -> String
+normalizePathSeparators =
+    unlines . map normalizePathSeparator . lines
+    where
+        normalizePathSeparator p =
+            if | any (isJust . parseURI) (tails p) -> p
+               | buildOS == Windows ->
+                    [if Posix.isPathSeparator c then Windows.pathSeparator else c| c <- p]
+               | otherwise ->
+                    [if Windows.isPathSeparator c then Posix.pathSeparator else c| c <- p]
+
+-- | @unlines@ from base will add a trailing newline if there isn't one already
+-- but this one doesn't
+--
+-- >>> lines "abc"
+-- ["abc"]
+--
+-- >>> Data.List.unlines $ lines "abc"
+-- "abc\n"
+--
+-- >>> unlines $ lines "abc"
+-- "abc"
+unlines :: [String] -> String
+unlines = maybe "" fst . unsnoc . Prelude.unlines
+
+-- | Replace line CRLF line breaks with LF line breaks.
+--
+-- >>> encodeLf "foo\nbar\r\nbaz"
+-- "foo\nbar\nbaz"
+--
+-- >>> encodeLf "foo\nbar\r\nbaz\n"
+-- "foo\nbar\nbaz\n"
+--
+-- >>> encodeLf "\nfoo\nbar\r\nbaz\n"
+-- "\nfoo\nbar\nbaz\n"
+--
+-- >>> encodeLf "\n\n\n"
+-- "\n\n\n"
+encodeLf :: String -> String
+encodeLf = filter (/= '\r')
+
+-- | Mark lines with visible delimiters, @^@ at the start and @$@ at the end.
+--
+-- >>> delimitLines ""
+-- "^$"
+--
+-- >>> delimitLines "\n"
+-- "^$\n"
+--
+-- >>> delimitLines "\n\n"
+-- "^$\n^$\n"
+--
+-- >>> delimitLines "\n\n\n"
+-- "^$\n^$\n^$\n"
+--
+-- >>> delimitLines $ encodeLf "foo\nbar\r\nbaz"
+-- "^foo$\n^bar$\n^baz$"
+--
+-- >>> delimitLines $ encodeLf "foo\nbar\r\nbaz\n"
+-- "^foo$\n^bar$\n^baz$\n"
+--
+-- >>> delimitLines $ encodeLf "\nfoo\nbar\r\nbaz\n"
+-- "^$\n^foo$\n^bar$\n^baz$\n"
+delimitLines:: String -> String
+delimitLines "" = "^$"
+delimitLines "\n" = "^$\n"
+delimitLines ('\n' : xs) = "^$\n" ++ delimitLines xs
+delimitLines output = fixupStart . fixupEnd $
+    foldr
+            (\c acc -> c :
+                if | "\n" == acc -> "$\n"
+                   |("\n" `isPrefixOf` acc) -> "$\n^" ++ drop 1 acc
+                   | otherwise -> acc
+            )
+            ""
+    output
+    where
+        fixupStart :: String -> String
+        fixupStart s@[] = s
+        fixupStart s@('^' : _) = s
+        fixupStart s = '^' : s
+
+        fixupEnd :: String -> String
+        fixupEnd s@[] = s
+        fixupEnd s@(reverse -> '$' : _) = s
+        fixupEnd s@(reverse -> '\n' : '$' : _) = s
+        fixupEnd s = s ++ "$"
diff --git a/cabal-testsuite/src/Test/Cabal/Prelude.hs b/cabal-testsuite/src/Test/Cabal/Prelude.hs
index 6455dbb87b1..daa5472c9d0 100644
--- a/cabal-testsuite/src/Test/Cabal/Prelude.hs
+++ b/cabal-testsuite/src/Test/Cabal/Prelude.hs
@@ -1,14 +1,17 @@
-{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE NondecreasingIndentation #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE CPP #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE ViewPatterns #-}
 
 -- | Generally useful definitions that we expect most test scripts
 -- to use.
 module Test.Cabal.Prelude (
     module Test.Cabal.Prelude,
     module Test.Cabal.Monad,
+    module Test.Cabal.NeedleHaystack,
     module Test.Cabal.Run,
     module System.FilePath,
     module Distribution.Utils.Path,
@@ -18,6 +21,7 @@ module Test.Cabal.Prelude (
     module Distribution.Simple.Program,
 ) where
 
+import Test.Cabal.NeedleHaystack
 import Test.Cabal.Script
 import Test.Cabal.Run
 import Test.Cabal.Monad
@@ -800,31 +804,46 @@ recordMode mode = withReaderT (\env -> env {
     testRecordUserMode = Just mode
     })
 
+-- See Note [Multiline Needles]
 assertOutputContains :: MonadIO m => WithCallStack (String -> Result -> m ())
-assertOutputContains needle result =
-    withFrozenCallStack $
-    unless (needle `isInfixOf` concatOutput output) $
-    assertFailure $ " expected: " ++ needle
-  where output = resultOutput result
+assertOutputContains = assertOn
+    needleHaystack
+        {txHaystack = TxContains{txBwd = delimitLines, txFwd = encodeLf}}
 
 assertOutputDoesNotContain :: MonadIO m => WithCallStack (String -> Result -> m ())
-assertOutputDoesNotContain needle result =
+assertOutputDoesNotContain = assertOn
+    needleHaystack
+        { expectNeedleInHaystack = False
+        , txHaystack = TxContains{txBwd = delimitLines, txFwd = encodeLf}
+        }
+
+-- See Note [Multiline Needles]
+assertOn :: MonadIO m => WithCallStack (NeedleHaystack -> String -> Result -> m ())
+assertOn NeedleHaystack{..} (txFwd txNeedle -> needle) (txFwd txHaystack. resultOutput -> output) =
     withFrozenCallStack $
-    when (needle `isInfixOf` concatOutput output) $
-    assertFailure $ "unexpected: " ++ needle
-  where output = resultOutput result
+    if expectNeedleInHaystack
+        then unless (needle `isInfixOf` output)
+            $ assertFailure $ "expected:\n" ++ (txBwd txNeedle needle) ++
+            if displayHaystack
+                then "\nin output:\n" ++ (txBwd txHaystack output)
+                else ""
+        else when (needle `isInfixOf` output)
+            $ assertFailure $ "unexpected:\n" ++ (txBwd txNeedle needle) ++
+            if displayHaystack
+                then "\nin output:\n" ++ (txBwd txHaystack output)
+                else ""
 
 assertOutputMatches :: MonadIO m => WithCallStack (String -> Result -> m ())
 assertOutputMatches regex result =
     withFrozenCallStack $
-    unless (concatOutput output =~ regex) $
+    unless (encodeLf output =~ regex) $
     assertFailure $ "expected regex match: " ++ regex
   where output = resultOutput result
 
 assertOutputDoesNotMatch :: MonadIO m => WithCallStack (String -> Result -> m ())
 assertOutputDoesNotMatch regex result =
     withFrozenCallStack $
-    when (concatOutput output =~ regex) $
+    when (encodeLf output =~ regex) $
     assertFailure $ "unexpected regex match: " ++ regex
   where output = resultOutput result
 
@@ -880,10 +899,6 @@ assertNoFileContains paths needle =
         \path ->
           assertFileDoesNotContain path needle
 
--- | Replace line breaks with spaces, correctly handling "\r\n".
-concatOutput :: String -> String
-concatOutput = unwords . lines . filter ((/=) '\r')
-
 -- | The directory where script build artifacts are expected to be cached
 getScriptCacheDirectory :: FilePath -> TestM FilePath
 getScriptCacheDirectory script = do
@@ -1274,3 +1289,32 @@ findDependencyInStore pkgName = do
                       [] -> error $ "Could not find " <> pkgName' <> " when searching for " <> pkgName' <> " in\n" <> show packageDirs
                       (dir:_) -> dir
       pure (storeDir </> storeDirForGhcVersion </> libDir)
+
+-- | It can be easier to paste expected output verbatim into a text file,
+-- especially if it is a multiline string, rather than encoding it as a multiline
+-- string in Haskell source code.
+--
+-- With `-XMultilineStrings` triple quoted strings with line breaks will be
+-- easier to write in source code but then this will only work with ghc-9.12.1
+-- and later, in which case we'd have to use CPP with test scripts to support
+-- older GHC versions. CPP doesn't play nicely with multiline strings using
+-- string gaps. None of our test script import other modules. That might be a
+-- way to avoid CPP in a module that uses multiline strings.
+--
+-- In summary, it is easier to read multiline strings from a file. That is what
+-- this function facilitates.
+--
+-- The contents of the file are read strictly to avoid problems seen on Windows
+-- deleting the file:
+--
+-- > cabal.test.hs:
+-- > C:\Users\<username>\AppData\Local\Temp\cabal-testsuite-8376\errors.expect.txt:
+-- > removePathForcibly:DeleteFile
+-- > "\\\\?\\C:\\Users\\<username>\\AppData\\Local\\Temp\\cabal-testsuite-8376\\errors.expect.txt":
+-- > permission denied (The process cannot access the file because it is being
+-- > used by another process.)
+readFileVerbatim :: FilePath -> TestM String
+readFileVerbatim filename = do
+  testDir <- testCurrentDir <$> getTestEnv
+  s <- liftIO . readFile $ testDir </> filename
+  length s `seq` return s
diff --git a/changelog.d/pr-10646.md b/changelog.d/pr-10646.md
new file mode 100644
index 00000000000..fb7dd8c9ec7
--- /dev/null
+++ b/changelog.d/pr-10646.md
@@ -0,0 +1,209 @@
+---
+synopsis: Configuration messages without duplicates
+packages: [cabal-install-solver]
+prs: 10646
+issues: 10645
+---
+
+The "using configuration from" message no longer has duplicates on Windows when
+a `cabal.project` uses forward slashes for its imports but the message reports
+the same import again with backslashes.
+
+```diff
+$ cat cabal.project
+import: dir-a/b.config
+
+$ cabal build all --dry-run
+...
+When using configuration from:
+-   - dir-a/b.config
+    - dir-a\b.config
+    - cabal.project
+```
+
+## Changed `Ord ProjectConfigPath` Instance
+
+For comparison purposes, path separators are normalized to the `buildOS`
+platform's path separator.
+
+```haskell
+-- >>> let abFwd = ProjectConfigPath $ "a/b.config" :| []
+-- >>> let abBwd = ProjectConfigPath $ "a\\b.config" :| []
+-- >>> compare abFwd abBwd
+-- EQ
+```
+
+## Changes in `cabal-testsuite`
+
+### Reading Expected Multiline Strings Verbatim
+
+With `ghc-9.12.1` adding `-XMultilineStrings`, writing multiline string
+expectations for `cabal-testsuite/PackageTests/**/*.test.hs` test scripts might
+be have been easier but for a catch. We run these tests with older `GHC`
+versions so would need to use `-XCPP` for those versions and the C preprocessor
+does not play nicely with string gaps. While it is possible to encode a
+multiline string as a single line with embedded LF characters or by breaking the
+line up arbitrarily and using `++` concatenation or by calling unlines on a list
+of lines, string gaps are the multiline strings of Haskell prior to
+`-XMultilineStrings`.
+
+To avoid these problems and for the convenience of pasting the expected value
+verbatim into a file, `readFileVerbatim` can read the expected multiline output
+for tests from a text file.  This has the same implementation as `readFile` from
+the `strict-io` package to avoid problems at cleanup.
+
+```
+Warning: Windows file locking hack: hit the retry limit 3 while trying to remove
+C:\Users\<username>\AppData\Local\Temp\cabal-testsuite-8376
+cabal.test.hs:
+C:\Users\<username>\AppData\Local\Temp\cabal-testsuite-8376\errors.expect.txt: removePathForcibly:DeleteFile
+"\\\\?\\C:\\Users\\<username>\\AppData\\Local\\Temp\\cabal-testsuite-8376\\errors.expect.txt":
+permission denied (The process cannot access the file because it is being used by another process.)
+```
+
+The other process accessing the file is `C:\WINDOWS\System32\svchost.exe`
+running a `QueryDirectory` event and this problem only occurs when the test
+fails.
+
+### Hidden Actual Value Modification
+
+The `assertOutputContains` function was modifying the actual value (the test
+output) with `concatOutput` before checking if it contained the expected value.
+This function, now renamed as `lineBreaksToSpaces`, would remove CR values and
+convert LF values to spaces.
+
+```haskell
+-- | Replace line breaks with spaces, correctly handling @"\\r\\n"@.
+--
+-- >>> lineBreaksToSpaces "foo\nbar\r\nbaz"
+-- "foo bar baz"
+--
+-- >>> lineBreaksToSpaces "foo\nbar\r\nbaz\n"
+-- "foo bar baz"
+--
+-- >>> lineBreaksToSpaces "\nfoo\nbar\r\nbaz\n"
+-- " foo bar baz"
+lineBreaksToSpaces :: String -> String
+```
+
+With this setup, false positives were possible. An expected value using string
+gaps and spaces would match a `concatOutput` modified actual value of
+"foo_bar_baz", where '_' was any of space, LF or CRLF in the unmodified actual
+value. The latter two are false positive matches.
+
+```haskell
+let expect = "foo \
+             \bar \
+             \baz"
+```
+
+False negatives were also possible. An expected value set up using string gaps
+with LF characters or with `-XMultilineStrings` wouldn't match an actual value
+of "foo_bar_baz", where '_' was either LF or CRLF because these characters had
+been replaced by spaces in the actual value, modified before the comparison.
+
+```haskell
+let expect = "foo\n\
+             \bar\n\
+             \baz"
+```
+
+```haskell
+{-# LANGUAGE MultilineStrings #-}
+
+let expect = """
+             foo
+             bar
+             baz
+             """
+```
+
+We had these problems:
+
+1. The actual value was changed before comparison and this change was not visible.
+2. The expected value was not changed in the same way as the actual value. This
+   made it possible for equal values to become unequal (false negatives) and for
+   unequal values to become equal (false positives).
+
+### Explicit Changes and Visible Line Delimiters
+
+To fix these problems, an added `assertOn` function takes a `NeedleHaystack`
+configuration for how the search is made, what to expect (to find the expected
+value or not) and how to display the expected and actual values.
+
+A pilcrow ¶ is often used to visibly display line endings but our terminal
+output is restricted to ASCII so lines are delimited between `^` and `$`
+markers. The needle (the expected output fragment) is shown annotated this way
+and the haystack (the actual output) can optionally be shown this way too.
+
+We can now implement `assertOutputContains` by calling `assertOn`:
+
+```diff
+    assertOutputContains :: MonadIO m => WithCallStack (String -> Result -> m ())
+-   assertOutputContains needle result =
+-       withFrozenCallStack $
+-       unless (needle `isInfixOf` (concatOutput output)) $
+-       assertFailure $ " expected: " ++ needle
+-   where output = resultOutput result
++   assertOutputContains = assertOn
++       needleHaystack
++           {txHaystack =
++               TxContains
++                   { txBwd = delimitLines
++                   , txFwd = encodeLf
++                   }
++           }
+```
+
+This is still a lenient match, allowing LF to match CRLF, but `encodeLf` doesn't
+replace LF with spaces like `concatOutput` (`lineBreaksToSpaces`) did:
+
+```haskell
+-- | Replace line CRLF line breaks with LF line breaks.
+--
+-- >>> encodeLf "foo\nbar\r\nbaz"
+-- "foo\nbar\nbaz"
+--
+-- >>> encodeLf "foo\nbar\r\nbaz\n"
+-- "foo\nbar\nbaz\n"
+--
+-- >>> encodeLf "\nfoo\nbar\r\nbaz\n"
+-- "\nfoo\nbar\nbaz\n"
+--
+-- >>> encodeLf "\n\n\n"
+-- "\n\n\n"
+encodeLf :: String -> String
+```
+
+If you choose to display the actual value by setting
+`NeedleHaystack{displayHaystack = True}` then its lines will be delimited.
+
+```haskell
+-- | Mark lines with visible delimiters, @^@ at the start and @$@ at the end.
+--
+-- >>> delimitLines ""
+-- "^$"
+--
+-- >>> delimitLines "\n"
+-- "^$\n"
+--
+-- >>> delimitLines "\n\n"
+-- "^$\n^$\n"
+--
+-- >>> delimitLines "\n\n\n"
+-- "^$\n^$\n^$\n"
+--
+-- >>> delimitLines $ encodeLf "foo\nbar\r\nbaz"
+-- "^foo$\n^bar$\n^baz$"
+--
+-- >>> delimitLines $ encodeLf "foo\nbar\r\nbaz\n"
+-- "^foo$\n^bar$\n^baz$\n"
+--
+-- >>> delimitLines $ encodeLf "\nfoo\nbar\r\nbaz\n"
+-- "^$\n^foo$\n^bar$\n^baz$\n"
+delimitLines:: String -> String
+```
+
+With `assertOn`, supplying string transformation to both the needle and haystack
+before comparison and before display can help find out why an expected value is
+or isn't found in the test output.

From 484ac9cb04b290c54facbc1c035c30b0ddc6628a Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Wed, 1 Jan 2025 08:03:39 -0500
Subject: [PATCH 3/4] Fix up existing tests with multiline expectations

---
 .../BuildDeps/InternalLibrary2/setup.test.hs  |   2 +-
 .../BuildDeps/InternalLibrary3/setup.test.hs  |   2 +-
 .../PackageTests/CheckSetup/setup.test.hs     |   8 +-
 .../ConditionalAndImport/cabal.test.hs        | 195 ++++++++----------
 .../PackageTests/NewBuild/T4288/cabal.test.hs |  10 +-
 .../DedupUsingConfigFromComplex/cabal.out     |   5 +-
 .../DedupUsingConfigFromComplex/cabal.test.hs |  15 +-
 ...endency-for-library-and-build-tool.test.hs |  18 +-
 8 files changed, 119 insertions(+), 136 deletions(-)

diff --git a/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary2/setup.test.hs b/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary2/setup.test.hs
index e36e33823d2..6b6da17f116 100644
--- a/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary2/setup.test.hs
+++ b/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary2/setup.test.hs
@@ -6,4 +6,4 @@ main = setupAndCabalTest . withPackageDb $ do
     assertEqual
         ("executable should have linked with the internal library")
         ("foo foo myLibFunc internal")
-        (concatOutput (resultOutput r))
+        (lineBreaksToSpaces $ resultOutput r)
diff --git a/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary3/setup.test.hs b/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary3/setup.test.hs
index 549e8bf8bb4..ac05c394383 100644
--- a/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary3/setup.test.hs
+++ b/cabal-testsuite/PackageTests/BuildDeps/InternalLibrary3/setup.test.hs
@@ -8,4 +8,4 @@ main = setupAndCabalTest . withPackageDb $ do
     assertEqual
         ("executable should have linked with the internal library")
         ("foo foo myLibFunc internal")
-        (concatOutput (resultOutput r))
+        (lineBreaksToSpaces $ resultOutput r)
diff --git a/cabal-testsuite/PackageTests/CheckSetup/setup.test.hs b/cabal-testsuite/PackageTests/CheckSetup/setup.test.hs
index 96ed4395785..67997e7e21b 100644
--- a/cabal-testsuite/PackageTests/CheckSetup/setup.test.hs
+++ b/cabal-testsuite/PackageTests/CheckSetup/setup.test.hs
@@ -13,8 +13,12 @@ main = cabalTest $ do
               "The dependency 'setup-depends: 'base' does not specify "
               ++ "an upper bound on the version number"
 
+        -- Replace line breaks with spaces in the haystack so that we can search
+        -- for a string that wraps lines.
+        let lineBreakBlind = needleHaystack{txHaystack = txContainsId{txFwd = lineBreaksToSpaces}}
+
         -- Asserts for the desired check messages after configure.
-        assertOutputContains libError1 checkResult
-        assertOutputContains libError2 checkResult
+        assertOn lineBreakBlind libError1 checkResult
+        assertOn lineBreakBlind libError2 checkResult
 
         return ()
diff --git a/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
index 67118d362c0..d0abb33de2d 100644
--- a/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
@@ -1,7 +1,6 @@
 import Test.Cabal.Prelude
-
-normalizeWindowsOutput :: String -> String
-normalizeWindowsOutput = if isWindows then map (\x -> case x of '/' -> '\\'; _ -> x) else id
+import Test.Cabal.OutputNormalizer
+import Data.Function ((&))
 
 main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   let log = recordHeader . pure
@@ -111,89 +110,65 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   --          +-- hops/hops-9.config (no further imports so not cyclical)
   log "checking that imports work skipping into a subfolder and then back out again and again"
   hopping <- cabal' "v2-build" [ "--project-file=hops-0.project" ]
-  assertOutputContains "Configuration is affected by the following files" hopping
-  assertOutputContains "- hops-0.project" hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops-6.config \
-    \    imported by: hops/hops-5.config \
-    \    imported by: hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops-8.config \
-    \    imported by: hops/hops-7.config \
-    \    imported by: hops-6.config \
-    \    imported by: hops/hops-5.config \
-    \    imported by: hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
 
-  assertOutputContains
-    (normalizeWindowsOutput "- hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops/hops-5.config \
-    \    imported by: hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops/hops-7.config \
-    \    imported by: hops-6.config \
-    \    imported by: hops/hops-5.config \
-    \    imported by: hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
-
-  assertOutputContains
-    (normalizeWindowsOutput "- hops/hops-9.config \
-    \    imported by: hops-8.config \
-    \    imported by: hops/hops-7.config \
-    \    imported by: hops-6.config \
-    \    imported by: hops/hops-5.config \
-    \    imported by: hops-4.config \
-    \    imported by: hops/hops-3.config \
-    \    imported by: hops-2.config \
-    \    imported by: hops/hops-1.config \
-    \    imported by: hops-0.project")
-    hopping
+  "Configuration is affected by the following files:\n\
+  \- hops-0.project\n\
+  \- hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops-6.config\n\
+  \    imported by: hops/hops-5.config\n\
+  \    imported by: hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops-8.config\n\
+  \    imported by: hops/hops-7.config\n\
+  \    imported by: hops-6.config\n\
+  \    imported by: hops/hops-5.config\n\
+  \    imported by: hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops/hops-5.config\n\
+  \    imported by: hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops/hops-7.config\n\
+  \    imported by: hops-6.config\n\
+  \    imported by: hops/hops-5.config\n\
+  \    imported by: hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project\n\
+  \- hops/hops-9.config\n\
+  \    imported by: hops-8.config\n\
+  \    imported by: hops/hops-7.config\n\
+  \    imported by: hops-6.config\n\
+  \    imported by: hops/hops-5.config\n\
+  \    imported by: hops-4.config\n\
+  \    imported by: hops/hops-3.config\n\
+  \    imported by: hops-2.config\n\
+  \    imported by: hops/hops-1.config\n\
+  \    imported by: hops-0.project"
+    & normalizeWindowsOutput
+    & flip (assertOn multilineNeedleHaystack) hopping
 
   -- The project is named oops as it is like hops but has conflicting constraints.
   -- +-- oops-0.project
@@ -208,22 +183,25 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   --          +-- oops/oops-9.config (has conflicting constraints)
   log "checking conflicting constraints skipping into a subfolder and then back out again and again"
   oopsing <- fails $ cabal' "v2-build" [ "all", "--project-file=oops-0.project" ]
-  assertOutputContains "rejecting: hashable-1.4.2.0" oopsing
-  assertOutputContains "rejecting: hashable-1.4.3.0" oopsing
-  assertOutputContains "(constraint from oops-0.project requires ==1.4.3.0)" oopsing
 
-  assertOutputContains
-    (normalizeWindowsOutput "      (constraint from oops/oops-9.config requires ==1.4.2.0) \
-    \        imported by: oops-8.config \
-    \        imported by: oops/oops-7.config \
-    \        imported by: oops-6.config \
-    \        imported by: oops/oops-5.config \
-    \        imported by: oops-4.config \
-    \        imported by: oops/oops-3.config \
-    \        imported by: oops-2.config \
-    \        imported by: oops/oops-1.config \
-    \        imported by: oops-0.project")
-    oopsing
+  "Could not resolve dependencies:\n\
+  \[__0] trying: oops-0.1 (user goal)\n\
+  \[__1] next goal: hashable (dependency of oops)\n\
+  \[__1] rejecting: hashable-1.4.3.0\n\
+  \      (constraint from oops/oops-9.config requires ==1.4.2.0)\n\
+  \        imported by: oops-8.config\n\
+  \        imported by: oops/oops-7.config\n\
+  \        imported by: oops-6.config\n\
+  \        imported by: oops/oops-5.config\n\
+  \        imported by: oops-4.config\n\
+  \        imported by: oops/oops-3.config\n\
+  \        imported by: oops-2.config\n\
+  \        imported by: oops/oops-1.config\n\
+  \        imported by: oops-0.project\n\
+  \[__1] rejecting: hashable-1.4.2.0\n\
+  \      (constraint from oops-0.project requires ==1.4.3.0)"
+    & normalizeWindowsOutput
+    & flip (assertOn multilineNeedleHaystack) oopsing
 
   -- The project is named yops as it is like hops but with y's for forks.
   -- +-- yops-0.project
@@ -264,13 +242,14 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
 
   log "checking that missing package message lists configuration provenance"
   missing <- fails $ cabal' "v2-build" [ "--project-file=cabal-missing-package.project" ]
-  assertOutputContains
-    (normalizeWindowsOutput "When using configuration from: \
-    \  - cabal-missing-package.project \
-    \  - missing/pkgs.config \
-    \  - missing/pkgs/default.config \
-    \The following errors occurred: \
-    \  - The package location 'pkg-doesnt-exist' does not exist.")
-    missing
+
+  "When using configuration from:\n\
+  \  - cabal-missing-package.project\n\
+  \  - missing/pkgs.config\n\
+  \  - missing/pkgs/default.config\n\
+  \The following errors occurred:\n\
+  \  - The package location 'pkg-doesnt-exist' does not exist."
+    & normalizeWindowsOutput
+    & flip (assertOn multilineNeedleHaystack) missing
 
   return ()
diff --git a/cabal-testsuite/PackageTests/NewBuild/T4288/cabal.test.hs b/cabal-testsuite/PackageTests/NewBuild/T4288/cabal.test.hs
index 3e3b8de853e..3313f596546 100644
--- a/cabal-testsuite/PackageTests/NewBuild/T4288/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/NewBuild/T4288/cabal.test.hs
@@ -1,4 +1,5 @@
 import Test.Cabal.Prelude
+import Data.Function ((&))
 
 -- This test is similar to the simplified example in issue #4288. The package's
 -- setup script only depends on base and setup-helper. setup-helper exposes a
@@ -10,8 +11,7 @@ main = cabalTest $ do
   skipUnless "no v2-build compatible boot-Cabal" =<< hasNewBuildCompatBootCabal
   r <- recordMode DoNotRecord $ cabal' "v2-build" ["T4288"]
   assertOutputContains "This is setup-helper-1.0." r
-  assertOutputContains
-      ("In order, the following will be built: "
-       ++ " - setup-helper-1.0 (lib:setup-helper) (first run) "
-       ++ " - T4288-1.0 (lib:T4288) (first run)")
-      r
+  "In order, the following will be built:\n\
+  \ - setup-helper-1.0 (lib:setup-helper) (first run)\n\
+  \ - T4288-1.0 (lib:T4288) (first run)"
+    & flip (assertOn multilineNeedleHaystack) r
diff --git a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.out b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.out
index 437612a2eca..43a3f25acc2 100644
--- a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.out
+++ b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.out
@@ -1,3 +1,4 @@
-# checking "using config from message" with URI imports
+# check "using config from message" with URI imports
 # cabal v2-build
-# checking that package directories and locations are reported in order
+# check project configuration with URI imports is listed in full and
+# check package directories and locations are reported in order
diff --git a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
index e354b356d7f..0c65ff68c60 100644
--- a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
@@ -1,4 +1,5 @@
 import Test.Cabal.Prelude
+import Data.Function ((&))
 
 main = cabalTest . recordMode RecordMarked $ do
   let log = recordHeader . pure
@@ -31,12 +32,12 @@ main = cabalTest . recordMode RecordMarked $ do
     out
 
   log "checking that package directories and locations are reported in order"
-  assertOutputContains
-    "The following errors occurred: \
-    \  - The package directory 'no-pkg-1' does not contain any .cabal file. \
-    \  - The package location 'no-pkg-2-dir' does not exist. \
-    \  - The package directory 'no-pkg-3' does not contain any .cabal file. \
-    \  - The package location 'no-pkg-4-dir' does not exist."
-    out
+
+  "The following errors occurred:\n\
+  \  - The package directory 'no-pkg-1' does not contain any .cabal file.\n\
+  \  - The package location 'no-pkg-2-dir' does not exist.\n\
+  \  - The package directory 'no-pkg-3' does not contain any .cabal file.\n\
+  \  - The package location 'no-pkg-4-dir' does not exist."
+    & flip (assertOn multilineNeedleHaystack) out
 
   return ()
diff --git a/cabal-testsuite/PackageTests/Regression/T5409/use-different-versions-of-dependency-for-library-and-build-tool.test.hs b/cabal-testsuite/PackageTests/Regression/T5409/use-different-versions-of-dependency-for-library-and-build-tool.test.hs
index 2a3eb3c093c..4bbb8b91a9b 100644
--- a/cabal-testsuite/PackageTests/Regression/T5409/use-different-versions-of-dependency-for-library-and-build-tool.test.hs
+++ b/cabal-testsuite/PackageTests/Regression/T5409/use-different-versions-of-dependency-for-library-and-build-tool.test.hs
@@ -1,4 +1,5 @@
 import Test.Cabal.Prelude
+import Data.Function ((&))
 
 -- The local package, pkg-1.0, depends on build-tool-pkg-1 as a library and
 -- build-tool-pkg-2 as a build-tool.  This test checks that cabal uses the
@@ -16,16 +17,13 @@ main = cabalTest $ withShorterPathForNewBuildStore $ do
       r1 <- recordMode DoNotRecord $
             cabal' "v2-build" ["pkg:my-exe"]
 
-      let msg = concat
-              [ "In order, the following will be built:"
-              , "  - build-tool-pkg-1 (lib) (requires build)"
-              , "  - build-tool-pkg-2 (lib) (requires build)"
-              , "  - build-tool-pkg-2 (exe:build-tool-exe) (requires build)"
-              , "  - pkg-1.0 (exe:my-exe) (first run)"
-              ]
+      "In order, the following will be built:\n\
+      \ - build-tool-pkg-1 (lib) (requires build)\n\
+      \ - build-tool-pkg-2 (lib) (requires build)\n\
+      \ - build-tool-pkg-2 (exe:build-tool-exe) (requires build)\n\
+      \ - pkg-1.0 (exe:my-exe) (first run)"
+        & flip (assertOn multilineNeedleHaystack) r1
 
-      assertOutputContains msg r1
       withPlan $ do
         r2 <- runPlanExe' "pkg" "my-exe" []
-        assertOutputContains
-            "build-tool library version: 1, build-tool exe version: 2" r2
+        assertOn multilineNeedleHaystack "build-tool library version: 1,\nbuild-tool exe version: 2" r2

From 32b820bbb3dd884b551a5d56229b341cde55d9d0 Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Wed, 1 Jan 2025 08:03:21 -0500
Subject: [PATCH 4/4] Add verbatim *.expect.txt expectations

- Add oops.expect.txt
- Add cabal-missing-package.expect.txt
- Add hops.expect.txt
- Add DedupUsingConfigFromComplex/errors.expect.txt
- Add using configuration from to errors.expect.txt
---
 .../cabal-missing-package.expect.txt          |  6 ++
 .../ConditionalAndImport/cabal.test.hs        | 93 ++-----------------
 .../ConditionalAndImport/hops.expect.txt      | 56 +++++++++++
 .../ConditionalAndImport/oops.expect.txt      | 16 ++++
 .../DedupUsingConfigFromComplex/cabal.test.hs | 37 +-------
 .../errors.expect.txt                         | 19 ++++
 6 files changed, 110 insertions(+), 117 deletions(-)
 create mode 100644 cabal-testsuite/PackageTests/ConditionalAndImport/cabal-missing-package.expect.txt
 create mode 100644 cabal-testsuite/PackageTests/ConditionalAndImport/hops.expect.txt
 create mode 100644 cabal-testsuite/PackageTests/ConditionalAndImport/oops.expect.txt
 create mode 100644 cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/errors.expect.txt

diff --git a/cabal-testsuite/PackageTests/ConditionalAndImport/cabal-missing-package.expect.txt b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal-missing-package.expect.txt
new file mode 100644
index 00000000000..f81a82a6c73
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal-missing-package.expect.txt
@@ -0,0 +1,6 @@
+When using configuration from:
+  - cabal-missing-package.project
+  - missing/pkgs.config
+  - missing/pkgs/default.config
+The following errors occurred:
+  - The package location 'pkg-doesnt-exist' does not exist.
diff --git a/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
index d0abb33de2d..681865df2e5 100644
--- a/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/ConditionalAndImport/cabal.test.hs
@@ -1,6 +1,7 @@
 import Test.Cabal.Prelude
 import Test.Cabal.OutputNormalizer
 import Data.Function ((&))
+import Data.Functor ((<&>))
 
 main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   let log = recordHeader . pure
@@ -78,7 +79,7 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   --    +-- etc
   log "checking that cyclical check catches a same file name that imports itself"
   cyclical4a <- fails $ cabal' "v2-build" [ "--project-file=cyclical-same-filename-out-out-self.project" ]
-  assertOutputContains (normalizeWindowsOutput "cyclical import of same-filename/cyclical-same-filename-out-out-self.config") cyclical4a
+  assertOutputContains (normalizePathSeparators "cyclical import of same-filename/cyclical-same-filename-out-out-self.config") cyclical4a
 
   -- +-- cyclical-same-filename-out-out-backback.project
   --  +-- cyclical-same-filename-out-out-backback.config
@@ -111,64 +112,8 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   log "checking that imports work skipping into a subfolder and then back out again and again"
   hopping <- cabal' "v2-build" [ "--project-file=hops-0.project" ]
 
-  "Configuration is affected by the following files:\n\
-  \- hops-0.project\n\
-  \- hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops-6.config\n\
-  \    imported by: hops/hops-5.config\n\
-  \    imported by: hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops-8.config\n\
-  \    imported by: hops/hops-7.config\n\
-  \    imported by: hops-6.config\n\
-  \    imported by: hops/hops-5.config\n\
-  \    imported by: hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops/hops-5.config\n\
-  \    imported by: hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops/hops-7.config\n\
-  \    imported by: hops-6.config\n\
-  \    imported by: hops/hops-5.config\n\
-  \    imported by: hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project\n\
-  \- hops/hops-9.config\n\
-  \    imported by: hops-8.config\n\
-  \    imported by: hops/hops-7.config\n\
-  \    imported by: hops-6.config\n\
-  \    imported by: hops/hops-5.config\n\
-  \    imported by: hops-4.config\n\
-  \    imported by: hops/hops-3.config\n\
-  \    imported by: hops-2.config\n\
-  \    imported by: hops/hops-1.config\n\
-  \    imported by: hops-0.project"
-    & normalizeWindowsOutput
-    & flip (assertOn multilineNeedleHaystack) hopping
+  readFileVerbatim "hops.expect.txt" >>=
+    flip (assertOn multilineNeedleHaystack) hopping .  normalizePathSeparators
 
   -- The project is named oops as it is like hops but has conflicting constraints.
   -- +-- oops-0.project
@@ -184,24 +129,8 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   log "checking conflicting constraints skipping into a subfolder and then back out again and again"
   oopsing <- fails $ cabal' "v2-build" [ "all", "--project-file=oops-0.project" ]
 
-  "Could not resolve dependencies:\n\
-  \[__0] trying: oops-0.1 (user goal)\n\
-  \[__1] next goal: hashable (dependency of oops)\n\
-  \[__1] rejecting: hashable-1.4.3.0\n\
-  \      (constraint from oops/oops-9.config requires ==1.4.2.0)\n\
-  \        imported by: oops-8.config\n\
-  \        imported by: oops/oops-7.config\n\
-  \        imported by: oops-6.config\n\
-  \        imported by: oops/oops-5.config\n\
-  \        imported by: oops-4.config\n\
-  \        imported by: oops/oops-3.config\n\
-  \        imported by: oops-2.config\n\
-  \        imported by: oops/oops-1.config\n\
-  \        imported by: oops-0.project\n\
-  \[__1] rejecting: hashable-1.4.2.0\n\
-  \      (constraint from oops-0.project requires ==1.4.3.0)"
-    & normalizeWindowsOutput
-    & flip (assertOn multilineNeedleHaystack) oopsing
+  readFileVerbatim "oops.expect.txt"
+    >>= flip (assertOn multilineNeedleHaystack) oopsing . normalizePathSeparators
 
   -- The project is named yops as it is like hops but with y's for forks.
   -- +-- yops-0.project
@@ -243,13 +172,7 @@ main = cabalTest . withRepo "repo" . recordMode RecordMarked $ do
   log "checking that missing package message lists configuration provenance"
   missing <- fails $ cabal' "v2-build" [ "--project-file=cabal-missing-package.project" ]
 
-  "When using configuration from:\n\
-  \  - cabal-missing-package.project\n\
-  \  - missing/pkgs.config\n\
-  \  - missing/pkgs/default.config\n\
-  \The following errors occurred:\n\
-  \  - The package location 'pkg-doesnt-exist' does not exist."
-    & normalizeWindowsOutput
-    & flip (assertOn multilineNeedleHaystack) missing
+  readFileVerbatim "cabal-missing-package.expect.txt"
+    >>= flip (assertOn multilineNeedleHaystack) missing . normalizePathSeparators
 
   return ()
diff --git a/cabal-testsuite/PackageTests/ConditionalAndImport/hops.expect.txt b/cabal-testsuite/PackageTests/ConditionalAndImport/hops.expect.txt
new file mode 100644
index 00000000000..bf3ea9bc001
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConditionalAndImport/hops.expect.txt
@@ -0,0 +1,56 @@
+Configuration is affected by the following files:
+- hops-0.project
+- hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops-6.config
+    imported by: hops/hops-5.config
+    imported by: hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops-8.config
+    imported by: hops/hops-7.config
+    imported by: hops-6.config
+    imported by: hops/hops-5.config
+    imported by: hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops/hops-1.config
+    imported by: hops-0.project
+- hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops/hops-5.config
+    imported by: hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops/hops-7.config
+    imported by: hops-6.config
+    imported by: hops/hops-5.config
+    imported by: hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
+- hops/hops-9.config
+    imported by: hops-8.config
+    imported by: hops/hops-7.config
+    imported by: hops-6.config
+    imported by: hops/hops-5.config
+    imported by: hops-4.config
+    imported by: hops/hops-3.config
+    imported by: hops-2.config
+    imported by: hops/hops-1.config
+    imported by: hops-0.project
diff --git a/cabal-testsuite/PackageTests/ConditionalAndImport/oops.expect.txt b/cabal-testsuite/PackageTests/ConditionalAndImport/oops.expect.txt
new file mode 100644
index 00000000000..88c23627575
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConditionalAndImport/oops.expect.txt
@@ -0,0 +1,16 @@
+Could not resolve dependencies:
+[__0] trying: oops-0.1 (user goal)
+[__1] next goal: hashable (dependency of oops)
+[__1] rejecting: hashable-1.4.3.0
+      (constraint from oops/oops-9.config requires ==1.4.2.0)
+        imported by: oops-8.config
+        imported by: oops/oops-7.config
+        imported by: oops-6.config
+        imported by: oops/oops-5.config
+        imported by: oops-4.config
+        imported by: oops/oops-3.config
+        imported by: oops-2.config
+        imported by: oops/oops-1.config
+        imported by: oops-0.project
+[__1] rejecting: hashable-1.4.2.0
+      (constraint from oops-0.project requires ==1.4.3.0)
diff --git a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
index 0c65ff68c60..e1419fb2467 100644
--- a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/cabal.test.hs
@@ -4,40 +4,13 @@ import Data.Function ((&))
 main = cabalTest . recordMode RecordMarked $ do
   let log = recordHeader . pure
 
-  log "checking \"using config from message\" with URI imports"
+  log "check \"using config from message\" with URI imports"
   out <- fails $ cabal' "v2-build" [ "all", "--dry-run", "--project-file=no-pkgs.project" ]
 
-  -- Use assertRegex when the output is tainted by the temp directory, like
-  -- this:
-  --
-  --   When using configuration from:
-  --   - /tmp/cabal-testsuite-282695/cabal.project
-  --   - /tmp/cabal-testsuite-282695/2.config etc
-  assertRegex
-    "Project configuration with URI imports is listed in full"
-    "When using configuration from:(\n|\r\n) \
-      \ .*no-pkgs\\.project(\n|\r\n) \
-      \ .*0\\.config(\n|\r\n) \
-      \ .*2\\.config(\n|\r\n) \
-      \ .*4\\.config(\n|\r\n) \
-      \ .*6\\.config(\n|\r\n) \
-      \ .*8\\.config(\n|\r\n) \
-      \ .*1\\.config(\n|\r\n) \
-      \ .*3\\.config(\n|\r\n) \
-      \ .*5\\.config(\n|\r\n) \
-      \ .*7\\.config(\n|\r\n) \
-      \ .*9\\.config(\n|\r\n) \
-      \ .*with-ghc\\.config(\n|\r\n) \
-      \ .*https://www.stackage.org/lts-21.25/cabal.config(\n|\r\n)"
-    out
+  log "check project configuration with URI imports is listed in full and"
+  log "check package directories and locations are reported in order"
 
-  log "checking that package directories and locations are reported in order"
-
-  "The following errors occurred:\n\
-  \  - The package directory 'no-pkg-1' does not contain any .cabal file.\n\
-  \  - The package location 'no-pkg-2-dir' does not exist.\n\
-  \  - The package directory 'no-pkg-3' does not contain any .cabal file.\n\
-  \  - The package location 'no-pkg-4-dir' does not exist."
-    & flip (assertOn multilineNeedleHaystack) out
+  readFileVerbatim "errors.expect.txt"
+    >>= flip (assertOn multilineNeedleHaystack) out . normalizePathSeparators
 
   return ()
diff --git a/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/errors.expect.txt b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/errors.expect.txt
new file mode 100644
index 00000000000..93907eea807
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectImport/DedupUsingConfigFromComplex/errors.expect.txt
@@ -0,0 +1,19 @@
+When using configuration from:
+  - no-pkgs.project
+  - 0.config
+  - 2.config
+  - 4.config
+  - 6.config
+  - 8.config
+  - cfg/1.config
+  - cfg/3.config
+  - cfg/5.config
+  - cfg/7.config
+  - cfg/9.config
+  - with-ghc.config
+  - https://www.stackage.org/lts-21.25/cabal.config
+The following errors occurred:
+  - The package directory 'no-pkg-1' does not contain any .cabal file.
+  - The package location 'no-pkg-2-dir' does not exist.
+  - The package directory 'no-pkg-3' does not contain any .cabal file.
+  - The package location 'no-pkg-4-dir' does not exist.