Windows portability (fix #16)

.github/workflows/haskell-ci.yml

@@ -8,9 +8,9 @@
 #
 # For more information, see https://github.com/haskell-CI/haskell-ci
 #
-# version: 0.13.20210606
+# version: 0.13.20210901
 #
-# REGENDATA ("0.13.20210606",["github","tasty-silver.cabal"])
+# REGENDATA ("0.13.20210901",["github","tasty-silver.cabal"])
 #
 name: Haskell-CI
 on:
@@ -26,15 +26,20 @@ jobs:
     strategy:
       matrix:
         include:
+          - compiler: ghc-9.2.0.20210821
+            compilerKind: ghc
+            compilerVersion: 9.2.0.20210821
+            setup-method: ghcup
+            allow-failure: true
           - compiler: ghc-9.0.1
             compilerKind: ghc
             compilerVersion: 9.0.1
             setup-method: hvr-ppa
             allow-failure: false
-          - compiler: ghc-8.10.4
+          - compiler: ghc-8.10.7
             compilerKind: ghc
-            compilerVersion: 8.10.4
-            setup-method: hvr-ppa
+            compilerVersion: 8.10.7
+            setup-method: ghcup
             allow-failure: false
           - compiler: ghc-8.8.4
             compilerKind: ghc
@@ -87,9 +92,17 @@ jobs:
         run: |
           apt-get update
           apt-get install -y --no-install-recommends gnupg ca-certificates dirmngr curl git software-properties-common libtinfo5
-          apt-add-repository -y 'ppa:hvr/ghc'
-          apt-get update
-          apt-get install -y "$HCNAME" cabal-install-3.4
+          if [ "${{ matrix.setup-method }}" = ghcup ]; then
+            mkdir -p "$HOME/.ghcup/bin"
+            curl -sL https://downloads.haskell.org/ghcup/0.1.16.2/x86_64-linux-ghcup-0.1.16.2 > "$HOME/.ghcup/bin/ghcup"
+            chmod a+x "$HOME/.ghcup/bin/ghcup"
+            "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER"
+            "$HOME/.ghcup/bin/ghcup" install cabal 3.4.0.0
+          else
+            apt-add-repository -y 'ppa:hvr/ghc'
+            apt-get update
+            apt-get install -y "$HCNAME" cabal-install-3.4
+          fi
         env:
           HCKIND: ${{ matrix.compilerKind }}
           HCNAME: ${{ matrix.compiler }}
@@ -101,16 +114,25 @@ jobs:
           echo "CABAL_DIR=$HOME/.cabal" >> "$GITHUB_ENV"
           echo "CABAL_CONFIG=$HOME/.cabal/config" >> "$GITHUB_ENV"
           HCDIR=/opt/$HCKIND/$HCVER
-          HC=$HCDIR/bin/$HCKIND
-          echo "HC=$HC" >> "$GITHUB_ENV"
-          echo "HCPKG=$HCDIR/bin/$HCKIND-pkg" >> "$GITHUB_ENV"
-          echo "HADDOCK=$HCDIR/bin/haddock" >> "$GITHUB_ENV"
-          echo "CABAL=/opt/cabal/3.4/bin/cabal -vnormal+nowrap" >> "$GITHUB_ENV"
+          if [ "${{ matrix.setup-method }}" = ghcup ]; then
+            HC=$HOME/.ghcup/bin/$HCKIND-$HCVER
+            echo "HC=$HC" >> "$GITHUB_ENV"
+            echo "HCPKG=$HOME/.ghcup/bin/$HCKIND-pkg-$HCVER" >> "$GITHUB_ENV"
+            echo "HADDOCK=$HOME/.ghcup/bin/haddock-$HCVER" >> "$GITHUB_ENV"
+            echo "CABAL=$HOME/.ghcup/bin/cabal-3.4.0.0 -vnormal+nowrap" >> "$GITHUB_ENV"
+          else
+            HC=$HCDIR/bin/$HCKIND
+            echo "HC=$HC" >> "$GITHUB_ENV"
+            echo "HCPKG=$HCDIR/bin/$HCKIND-pkg" >> "$GITHUB_ENV"
+            echo "HADDOCK=$HCDIR/bin/haddock" >> "$GITHUB_ENV"
+            echo "CABAL=/opt/cabal/3.4/bin/cabal -vnormal+nowrap" >> "$GITHUB_ENV"
+          fi
+
           HCNUMVER=$(${HC} --numeric-version|perl -ne '/^(\d+)\.(\d+)\.(\d+)(\.(\d+))?$/; print(10000 * $1 + 100 * $2 + ($3 == 0 ? $5 != 1 : $3))')
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((HCNUMVER >= 90200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
           echo "GHCJSARITH=0" >> "$GITHUB_ENV"
         env:
@@ -139,6 +161,17 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          EOF
+          fi
           cat $CABAL_CONFIG
       - name: versions
         run: |
@@ -186,7 +219,10 @@ jobs:
           if [ $((HCNUMVER >= 80200)) -ne 0 ] ; then echo "    ghc-options: -Werror=missing-methods" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
-          $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: $_ installed\n" unless /^(bytestring|process|tasty-silver)$/; }' >> cabal.project.local
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
+          $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: $_ installed\n" unless /^(bytestring|directory|process|tasty-silver)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
       - name: dump install plan

.github/workflows/macOS.yml

@@ -64,4 +64,4 @@ jobs:
 
     - name: Test
       run: |
-        cabal test
+        cabal test --test-show-details=direct --test-options=-i

.github/workflows/windows.yml

@@ -64,4 +64,4 @@ jobs:
 
     - name: Test
       run: |
-        cabal test
+        cabal test --test-show-details=direct --test-options=-i

CHANGELOG.md

@@ -1,118 +1,126 @@
 Changes
 =======
 
+Version 3.3 (20 Sep 2021)
+-----------
+
+* Windows portability (#16):
+  - Calls to `git diff` are no longer indirected via `sh -c`.
+  - When indirection via `sh -c` is used, backslashes in filenames are converted to slashes.
+* Tested with GHC 7.4 - 9.2.1-RC1
+
 Version 3.2.3 (13 Sep 2021)
 -------------
 
 * Tested with GHC 7.4 - 9.0 (fixed compilation with GHC 7.4 - 7.8)
 * CI via GitHub Actions on platforms `ubuntu`, `macOS`, `windows`.
 
-Version 3.2.2
+Version 3.2.2 (22 Jun 2021)
 -------------
 
 * Fix cabal warning (#27, thanks to felixonmars)
 
-Version 3.2.1
+Version 3.2.1 (22 Dec 2020)
 -------------
 
 * Fix option parser (#25)
 
-Version 3.2
+Version 3.2 (21 Dec 2020)
 -----------
 
 * Compatibility with tasty 1.4 (breaks compatibility with older versions of tasty)
 
-Version 3.1.15
+Version 3.1.15 (8 Jun 2020)
 --------------
 
 * Fix missing space in git diff calls introduced in v3.1.14 (#22, thanks to croyzor)
 
-Version 3.1.14
+Version 3.1.14 (8 Jun 2020)
 --------------
 
 * Fix wrong interpretation of git diff exit codes (#21, thanks to croyzor)
 
-Version 3.1.13
+Version 3.1.13 (12 Jul 2019)
 --------------
 
 * Add option to disable ansi tricks (#18, thanks to L-TChen)
 
-Version 3.1.12
+Version 3.1.12 (24 Sep 2018)
 --------------
 
 * Fix compilation with GHC 8.4 (thanks to asr)
 
-Version 3.1.11
+Version 3.1.11 (29 Dec 2017)
 --------------
 
 * Fix compilation with GHC 8.4
 
-Version 3.1.10
+Version 3.1.10 (1 Apr 2017)
 --------------
 
 * Better error handling for calls to external tools (`git diff`)
 
-Version 3.1.9
+Version 3.1.9 (29 Aug 2016)
 -------------
 
 * Fix compilation with optparse-applicative 0.13.*.
 * Provide character-level diff if wdiff and colordiff are available.
 
-Version 3.1.8.1
+Version 3.1.8.1 (19 Jan 2016)
 ---------------
 
 * Fix compilation with GHC 8.
 
-Version 3.1.8
+Version 3.1.8 (10 Nov 2015)
 -------------
 
 * Make update function optional for test cases.
 
-Version 3.1.7
+Version 3.1.7 (14 May 2015)
 -------------
 
 * Add feature to disable certain tests, still showing them in the UI
   but not running them.
 * Fix a concurrency issue in the interactive test runner.
 
-Version 3.1.6
+Version 3.1.6 (14 May 2015)
 -------------
 
 * Expose regex filter modules.
 * Fix issue with regex filters when used together with withResource nodes.
 
-Version 3.1.5
+Version 3.1.5 (12 Apr 2015)
 -------------
 
 * Add experimental --regex-include option to select tests using a regex.
   This option is highly experimental and may change in later versions!
 * The --regex-include/--regex-exclude option may be given multiple times now.
   The exclusion regexes are applied first, after that all inclusion regexes.
 
-Version 3.1.4
+Version 3.1.4 (12 Apr 2015)
 -------------
 
 * Add experimental --regex-exclude option to filter out tests using a regex.
   This option is highly experimental and may change in later versions!
 
-Version 3.1.3
+Version 3.1.3 (6 Apr 2015)
 -------------
 
 * Use package temporary instead of temporary-rc.
 * Re-add command line options for test runner which were accidentally removed.
 
-Version 3.1.2
+Version 3.1.2 (6 Apr 2015)
 -------------
 
 * Add non-interactive mode to test runner, printing diffs/actual values directly to stdout.
   Useful for (travis) CI.
 
-Version 3.1.1
+Version 3.1.1 (4 Apr 2015)
 -------------
 
 * Report success instead of failure if new result is accepted in interactive mode.
 
-Version 3.1
+Version 3.1 (4 Apr 2015)
 -----------
 
 * Fixed & tested support for GHC 7.4.2 - 7.10.1
@@ -121,7 +129,7 @@ Version 3.1
 * Enable travis CI builds
 
 Version 3.0 - 3.0.2.2
------------
+---------------------
 
 * Refactored API
 * Add interactive mode

README.md

@@ -23,6 +23,25 @@ to the user. Based upon this diff, the user can choose to update the golden stan
 fix the test case as necessary. Interactive mode requires that at least `git diff` and `less` is
 available, or preferrably `wdiff` and `colordiff` for character-based diffs.
 
+Portability
+-----------
+
+`tasty-silver` aims to work under Linux, macOS, and Windows.  In
+particular, it should work in the [GitHub CI virtual
+environments](https://github.com/actions/virtual-environments).
+
+Known limitations:
+
+- On `macOS`, GHC ≥ 7.10 is required, as GHC ≤ 7.8 produces code that
+  is not compatible with the System Integrity Protection mechanism of
+  Mac OS X.  In particular, you could see errors like:
+  ```
+  /usr/bin/less: getPermissions:fileAccess: permission denied (Operation not permitted)
+  ```
+
+- On Windows, the colored diff may not be available as it depends on
+  the availability of `colordiff`, `less`, `sh`, and `wdiff`.
+
 Examples
 --------
 

Test/Tasty/Silver.hs

@@ -3,42 +3,45 @@
 {- |
 This module provides a simplified interface. If you want more, see "Test.Tasty.Silver.Advanced".
 
-Note about filenames. They are looked up in the usual way, thus relative
+=== Note about filenames
+
+They are looked up in the usual way, thus relative
 names are relative to the processes current working directory.
 It is common to run tests from the package's root directory (via @cabal
-test@ or @cabal install --enable-tests@), so if your test files are under
+test@ or @stack test@), so if your test files are under
 the @tests\/@ subdirectory, your relative file names should start with
 @tests\/@ (even if your @test.hs@ is itself under @tests\/@, too).
 
-Note about line endings. The best way to avoid headaches with line endings
+=== Note about line endings
+
+The best way to avoid headaches with line endings
 (when running tests both on UNIX and Windows) is to treat your golden files
 as binary, even when they are actually textual.
 
 This means:
 
 * When writing output files from Haskell code, open them in binary mode
-(see 'openBinaryFile', 'withBinaryFile' and 'hSetBinaryMode'). This will
-disable automatic @\\n -> \\r\\n@ conversion on Windows. For convenience, this
-module exports 'writeBinaryFile' which is just like `writeFile` but opens
-the file in binary mode. When using 'ByteString's note that
+(see 'System.IO.openBinaryFile', 'System.IO.withBinaryFile' and 'System.IO.hSetBinaryMode'). This will
+disable automatic @\\n -> \\r\\n@ conversion on Windows.
+When using 'Data.ByteString.ByteString', note that
 "Data.ByteString" and "Data.ByteString.Lazy" use binary mode for
-@writeFile@, while "Data.ByteString.Char8" and "Data.ByteString.Lazy.Char8"
+@'writeFile'@, while "Data.ByteString.Char8" and "Data.ByteString.Lazy.Char8"
 use text mode.
 
-* Tell your VCS not to do any newline conversion for golden files. For
- git check in a @.gitattributes@ file with the following contents (assuming
+* Tell your version control not to do any newline conversion for golden files. For
+ git, check in a @.gitattributes@ file with the following contents (assuming
  your golden files have @.golden@ extension):
 
 >*.golden	-text
 
-On its side, tasty-golden reads and writes files in binary mode, too.
+On its side, `tasty-silver` reads and writes files in binary mode, too.
 
 Why not let Haskell/git do automatic conversion on Windows? Well, for
 instance, @tar@ will not do the conversion for you when unpacking a release
-tarball, so when you run @cabal install your-package --enable-tests@, the
+tarball, so when you run e.g. @stack install your-package --tests@, the
 tests will be broken.
 
-As a last resort, you can strip all @\\r@s from both arguments in your
+As a last resort, you can strip all @\\r@ characters from both arguments in your
 comparison function when necessary. But most of the time treating the files
 as binary does the job.
 -}
@@ -68,7 +71,7 @@ import System.Exit
 import System.FilePath
 import System.Process.Text as PT
 
-import Test.Tasty.Providers
+import Test.Tasty.Providers (TestTree, TestName)
 import Test.Tasty.Silver.Advanced
 
 -- | Compare a given file contents against the golden file contents. Assumes that both text files are utf8 encoded.
@@ -146,12 +149,11 @@ printProcResult (ex, a, b) = T.unlines (["ret > " `T.append` T.pack (show ex)]
 
 -- | Find all files in the given directory and its subdirectories that have
 -- the given extensions.
---
 -- It is typically used to find all test files and produce a golden test
 -- per test file.
 --
--- The returned paths use forward slashes to separate path components,
--- even on Windows. Thus if the file name ends up in a golden file, it
+-- The returned paths use forward slashes (@'/'@) to separate path components,
+-- /even on Windows/. Thus if the file name ends up in a golden file, it
 -- will not differ when run on another platform.
 --
 -- The semantics of extensions is the same as in 'takeExtension'. In
@@ -162,25 +164,21 @@ printProcResult (ex, a, b) = T.unlines (["ret > " `T.append` T.pack (show ex)]
 --
 -- It doesn't do anything special to handle symlinks (in particular, it
 -- probably won't work on symlink loops).
---
 -- Nor is it optimized to work with huge directory trees (you'd probably
 -- want to use some form of coroutines for that).
 findByExtension
   :: [FilePath] -- ^ extensions
   -> FilePath -- ^ directory
   -> IO [FilePath] -- ^ paths
-findByExtension extsList = go where
+findByExtension extsList = go
+  where
   exts = Set.fromList extsList
   go dir = do
     allEntries <- getDirectoryContents dir
     let entries = filter (not . (`elem` [".", ".."])) allEntries
     liftM concat $ forM entries $ \e -> do
-      let path = dir ++ "/" ++ e
+      let path = dir ++ "/" ++ e         -- NOT </>! Slash accepted even on Windows.
       isDir <- doesDirectoryExist path
       if isDir
         then go path
-        else
-          return $
-            if takeExtension path `Set.member` exts
-              then [path]
-              else []
+        else return [ path | takeExtension path `Set.member` exts ]

Test/Tasty/Silver/Advanced.hs

@@ -2,7 +2,7 @@
 {-# LANGUAGE CPP #-}
 
 module Test.Tasty.Silver.Advanced
-  ( -- * The main function
+  ( -- * Constructing golden tests
     goldenTest1,
 
     goldenTestIO,
@@ -12,7 +12,7 @@ module Test.Tasty.Silver.Advanced
     GShow (..),
     GDiff (..),
 
-    -- * reading files
+    -- * Reading files
     readFileMaybe
   )
 where

Test/Tasty/Silver/Filter.hs

@@ -38,6 +38,7 @@ import Test.Tasty hiding (defaultMain)
 import Test.Tasty.Options
 import Test.Tasty.Runners
 
+-- | Path into the 'TestTree'.  Separator is the slash character(@'/'@).
 type TestPath = String
 
 -- we have to store the regex as String, as there is no Typeable instance
@@ -97,9 +98,10 @@ filterWithRegex opts = filterWithPred (checkRF True $ excRgxs ++ incRgxs)
 -- are met:
 -- 1. At least one RFInclude matches.
 -- 2. No RFExclude filter matches.
-checkRF :: Bool -- ^ If true, ignore 1. condition if no RFInclude is given.
+checkRF :: Bool -- ^ If 'True', ignore first condition if no 'RFInclude' is given.
     -> [RegexFilter]
-    -> TestPath -> Bool
+    -> TestPath
+    -> Bool
 checkRF ignNoInc rf tp =
   ((null incRgxs && ignNoInc) || any regexMatches incRgxs)
     && (not $ any regexMatches excRgxs)

Test/Tasty/Silver/Interactive/Run.hs

@@ -7,12 +7,14 @@ module Test.Tasty.Silver.Interactive.Run
   )
   where
 
+import Data.Tagged
+import Data.Typeable
+
 import Test.Tasty hiding (defaultMain)
-import Test.Tasty.Runners
 import Test.Tasty.Options
-import Data.Typeable
-import Data.Tagged
 import Test.Tasty.Providers
+import Test.Tasty.Runners
+import Test.Tasty.Silver.Filter ( TestPath )
 
 data CustomTestExec t = IsTest t => CustomTestExec t (OptionSet -> t -> (Progress -> IO ()) -> IO Result)
   deriving (Typeable)
@@ -21,10 +23,9 @@ instance IsTest t => IsTest (CustomTestExec t) where
   run opts (CustomTestExec t r) cb = r opts t cb
   testOptions = retag $ (testOptions :: Tagged t [OptionDescription])
 
-type TestPath = String
-
 -- | Provide new test run function wrapping the existing tests.
-wrapRunTest :: (forall t . IsTest t => TestPath -> TestName -> OptionSet -> t -> (Progress -> IO ()) -> IO Result)
+wrapRunTest
+    :: (forall t . IsTest t => TestPath -> TestName -> OptionSet -> t -> (Progress -> IO ()) -> IO Result)
     -> TestTree
     -> TestTree
 wrapRunTest = wrapRunTest' "/"

Test/Tasty/Silver/Internal.hs

@@ -24,7 +24,7 @@ import System.IO.Error
 import Test.Tasty.Providers
 import Test.Tasty.Options
 
--- | See 'goldenTest1' for explanation of the fields.
+-- | See 'Test.Tasty.Silver.Advanced.goldenTest1' for explanation of the fields.
 
 data Golden =
   forall a .
@@ -49,7 +49,7 @@ instance IsOption AcceptTests where
   optionHelp = return "Accept current results of golden tests"
   optionCLParser =  flagCLParser Nothing (AcceptTests True)
 
--- | Read the file if it exists, else return Nothing.
+-- | Read the file if it exists, else return 'Nothing'.
 -- Useful for reading golden files.
 
 readFileMaybe :: FilePath -> IO (Maybe SB.ByteString)
@@ -130,3 +130,38 @@ instance Show (GoldenResult' m) where
   show GREqual = "GREqual"
   show (GRDifferent {}) = "GRDifferent"
   show (GRNoGolden {}) = "GRNoGolden"
+
+
+-- * Generic utilites
+
+-- | Monadic @if@.
+
+ifM :: Monad m => m Bool -> m a -> m a -> m a
+ifM mc mt me = do
+  c <- mc
+  if c then mt else me
+
+-- | Monadic @if (not ...) ...@.
+
+ifNotM :: Monad m => m Bool -> m a -> m a -> m a
+ifNotM mc = flip $ ifM mc
+
+-- | Short-cutting version of @'liftM2' (&&)@.
+
+and2M :: Monad m => m Bool -> m Bool -> m Bool
+and2M ma mb = ifM ma mb $ return False
+
+-- | Short-cutting version of @'and' . 'sequence'@.
+
+andM :: Monad m => [m Bool] -> m Bool
+andM = Prelude.foldl and2M (return True)
+
+-- | Short-cutting version of @'liftM2' (||)@.
+
+or2M :: Monad m => m Bool -> m Bool -> m Bool
+or2M ma mb = ifM ma (return True) mb
+
+-- | Short-cutting version of @'or' . 'sequence'@.
+
+orM :: Monad m => [m Bool] -> m Bool
+orM = Prelude.foldl or2M (return False)

cabal.haskell-ci

@@ -1 +1,5 @@
-installed: +all -bytestring -process
+installed: +all -bytestring -directory -process
+
+-- on Linux we can use ghcup to setup (some) of jobs
+-- hvr-ppa latest are 9.0.1 and 8.10.4
+ghcup-jobs: >= 9.2 || > 8.10.4 && < 9.0

tasty-silver.cabal

@@ -1,16 +1,16 @@
 name:                tasty-silver
-version:             3.2.3
+version:             3.3
 synopsis:            A fancy test runner, including support for golden tests.
 description:
   This package provides a fancy test runner and support for «golden testing».
-
+  .
   A golden test is an IO action that writes its result to a file.
   To pass the test, this output file should be identical to the corresponding
   «golden» file, which contains the correct result for the test.
-
+  .
   The test runner allows filtering tests using regexes, and to interactively
   inspect the result of golden tests.
-
+  .
   This package is a heavily extended fork of tasty-golden.
 
 license:             MIT
@@ -29,8 +29,9 @@ extra-source-files:
   README.md
 
 tested-with:
+  GHC == 9.2.0.20210821
   GHC == 9.0.1
-  GHC == 8.10.4
+  GHC == 8.10.7
   GHC == 8.8.4
   GHC == 8.6.5
   GHC == 8.4.4
@@ -63,25 +64,29 @@ library
       -Wcompat
 
   build-depends:
-    ansi-terminal >= 0.6.2.1,
-    async,
-    base >= 4.5,
-      -- regex-tdfa has this lower bound on base, so we make it explicit here
-    bytestring >= 0.9.2.1,
-    containers,
-    directory,
-    deepseq,
-    filepath,
-    mtl,
-    optparse-applicative,
-    process >= 1.2,
-    process-extras >= 0.2,
-    regex-tdfa >= 1.2.0,
-    stm >= 2.4.2,
-    tagged,
-    tasty >= 1.4,
-    temporary,
-    text >= 0.11.0.0
+    base >= 4.5
+        -- regex-tdfa has this lower bound on base, so we make it explicit here
+    , ansi-terminal >= 0.6.2.1
+    , async
+    , bytestring >= 0.9.2.1
+    , containers
+    , directory >= 1.2.3.0
+        -- withCurrentDirectory needs >= 1.2.3.0
+    , deepseq
+    , filepath
+    , mtl
+    , optparse-applicative
+    , process >= 1.2
+    , process-extras >= 0.3
+        -- readCreateProcessWithExitCode needs >= 0.3
+    , regex-tdfa >= 1.2.0
+    , silently >= 1.2.5.1
+        -- Andreas Abel, 2021-09-05, latest silently is today 1.2.5.1
+    , stm >= 2.4.2
+    , tagged
+    , tasty >= 1.4
+    , temporary
+    , text >= 0.11.0.0
   if impl(ghc < 8.0)
     build-depends: semigroups >= 0.18.3
 
@@ -106,6 +111,8 @@ Test-suite test
         -- Andreas Abel, 2021-09-05, latest silently is today 1.2.5.1
     , temporary
     , transformers >= 0.3
+  if impl(ghc < 8.0)
+    build-depends: semigroups
 
   if impl(ghc >= 8.0)
     ghc-options:

tests/test.hs

@@ -1,16 +1,22 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 
 import Control.Concurrent.MVar
-import Control.Monad (unless)
-import Control.Monad.IO.Class (liftIO)
+import Control.Exception as E ( catch, SomeException )
+  -- Prelude of GHC 7.4 also has @catch@, so we disambiguate with E.catch
+import Control.Monad          ( unless )
+import Control.Monad.IO.Class ( liftIO )
+
 import Data.List (sort)
 #if !(MIN_VERSION_base(4,8,0))
-import Data.Monoid (mempty)
+import Data.Functor           ( (<$) )
+import Data.Monoid            ( mempty )
 #endif
 
-import System.Directory
+import System.Directory       ( createDirectory, withCurrentDirectory )
 import System.FilePath
-import System.IO.Silently (capture)
+import System.IO.Silently     ( capture )
 import System.IO.Temp
 
 import Test.Tasty hiding (defaultMain)
@@ -28,17 +34,21 @@ touch f = writeFile f ""
 
 main :: IO ()
 main = defaultMain $ testGroup "tests" $
+  testShowDiff :
   testFindByExt :
   testWithResource :
   testCheckRF :
+  -- Andreas, 2021-09-18
+  -- @testGolden@ always fails, would need @--accept@ mode.
+  -- testGolden :
   []
 
 testFindByExt :: TestTree
 testFindByExt =
   testCase "findByExtension" $
     withSystemTempDirectory "golden-test" $ \basedir -> do
-
-      setCurrentDirectory basedir
+     withCurrentDirectory basedir $ do
+      -- Andreas 2021-09-07: setCurrentDirectory would affect other tests!
 
       createDirectory ("d1")
       createDirectory ("d1" </> "d2")
@@ -58,10 +68,45 @@ testFindByExt =
         , "./f2.h"
         ]
 
+testShowDiff :: TestTree
+testShowDiff =
+  testCase "showDiff" $
+    withSystemTempDirectory "golden-test" $ \ dir -> do
+      let
+        goldenFile  = dir </> "golden.txt"
+        goldenValue = "golden value"
+        actualFile  = dir </> "actual.txt"
+        actualValue = "actual value"
+        tree        = goldenVsFile "showDiff-internal" goldenFile actualFile $
+                        writeFile actualFile actualValue
+      writeFile goldenFile goldenValue
+      writeFile actualFile actualValue
+      do
+          -- let io = defaultMain tree
+          let io = runTestsInteractive (const False) mempty tree
+          (out, success) <- capture $ E.catch (True <$ io) $ \ (e :: SomeException) -> do
+             print e
+             return False
+          -- unless success $ putStr out
+          putStr out
+          assertBool "Test should succeed." success
+
+-- UNUSED, but KEEP!
+-- testGolden :: TestTree
+-- testGolden =
+--   goldenTest1
+--     "wrongOutput"
+--     (return $ Just "golden value")
+--     (return "actual value")
+--     (DiffText Nothing)   -- always fail
+--     ShowText
+--     (const $ return ())  -- keep the golden file no matter what
+
 -- | Check if resources are properly initialized.
 testWithResource :: TestTree
 testWithResource =
   testCase "withResource" $
+    -- The @AcceptTests True@ option automatically replaces the golden value.
     case tryIngredients [consoleTestReporter] (singleOption $ AcceptTests True) tree of
       Just r' -> do
         (out, success) <- capture r'