diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 884140c4e6..b8fda76503 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -215,3 +215,7 @@ jobs:
       - if: ${{ needs.pre_job.outputs.should_skip != 'true' && matrix.test}}
         name: Test hls-rename-plugin test suite
         run: cabal test hls-rename-plugin --test-options="-j1 --rerun-update" || cabal test hls-rename-plugin --test-options="-j1 --rerun" || LSP_TEST_LOG_COLOR=0 LSP_TEST_LOG_MESSAGES=true LSP_TEST_LOG_STDERR=true cabal test hls-rename-plugin --test-options="-j1 --rerun"
+
+      - if: ${{ needs.pre_job.outputs.should_skip != 'true' && matrix.test}}
+        name: Test hls-hlint-plugin test suite
+        run: cabal test hls-hlint-plugin --test-options="-j1 --rerun-update" || cabal test hls-hlint-plugin --test-options="-j1 --rerun" || LSP_TEST_LOG_COLOR=0 LSP_TEST_LOG_MESSAGES=true LSP_TEST_LOG_STDERR=true cabal test hls-hlint-plugin --test-options="-j1 --rerun"
diff --git a/haskell-language-server.cabal b/haskell-language-server.cabal
index 032a8b699f..0002f6932b 100644
--- a/haskell-language-server.cabal
+++ b/haskell-language-server.cabal
@@ -21,9 +21,6 @@ extra-source-files:
   test/testdata/**/*.project
   test/testdata/**/*.cabal
   test/testdata/**/*.yaml
-  -- this one is not matched by the previous glob
-  test/testdata/hlint/ignore/.hlint.yaml
-  test/testdata/**/*.h
   test/testdata/**/*.hs
 
 flag pedantic
diff --git a/hls-test-utils/src/Test/Hls.hs b/hls-test-utils/src/Test/Hls.hs
index 512ae1b744..dec2542f7a 100644
--- a/hls-test-utils/src/Test/Hls.hs
+++ b/hls-test-utils/src/Test/Hls.hs
@@ -24,8 +24,10 @@ module Test.Hls
     waitForAllProgressDone,
     PluginDescriptor,
     IdeState,
-    waitForBuildQueue
-    ,waitForTypecheck,waitForAction)
+    waitForBuildQueue,
+    waitForTypecheck,
+    waitForAction,
+    sendConfigurationChanged)
 where
 
 import           Control.Applicative.Combinators
@@ -222,8 +224,12 @@ waitForAction key TextDocumentIdentifier{_uri} = do
     return $ do
       e <- _result
       case A.fromJSON e of
-        A.Error e   -> Left $ ResponseError InternalError (T.pack e) Nothing
+        A.Error err   -> Left $ ResponseError InternalError (T.pack err) Nothing
         A.Success a -> pure a
 
 waitForTypecheck :: TextDocumentIdentifier -> Session (Either ResponseError Bool)
 waitForTypecheck tid = fmap ideResultSuccess <$> waitForAction "typecheck" tid
+
+sendConfigurationChanged :: Value -> Session ()
+sendConfigurationChanged config =
+  sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams config)
diff --git a/hls-test-utils/src/Test/Hls/Util.hs b/hls-test-utils/src/Test/Hls/Util.hs
index 05e06b7d64..9add1ca02f 100644
--- a/hls-test-utils/src/Test/Hls/Util.hs
+++ b/hls-test-utils/src/Test/Hls/Util.hs
@@ -22,6 +22,7 @@ module Test.Hls.Util
     , ghcVersion, GhcVersion(..)
     , hostOS, OS(..)
     , matchesCurrentEnv, EnvSpec(..)
+    , noLiteralCaps
     , ignoreForGhcVersions
     , ignoreInEnv
     , inspectCodeAction
@@ -74,6 +75,12 @@ import           Test.Tasty.HUnit                (Assertion, assertFailure,
 import           Text.Blaze.Internal             hiding (null)
 import           Text.Blaze.Renderer.String      (renderMarkup)
 
+noLiteralCaps :: C.ClientCapabilities
+noLiteralCaps = def { C._textDocument = Just textDocumentCaps }
+  where
+    textDocumentCaps = def { C._codeAction = Just codeActionCaps }
+    codeActionCaps = CodeActionClientCapabilities (Just True) Nothing Nothing Nothing Nothing Nothing Nothing
+
 codeActionSupportCaps :: C.ClientCapabilities
 codeActionSupportCaps = def { C._textDocument = Just textDocumentCaps }
   where
diff --git a/plugins/hls-hlint-plugin/hls-hlint-plugin.cabal b/plugins/hls-hlint-plugin/hls-hlint-plugin.cabal
index 3153e1cb33..316bdf0f36 100644
--- a/plugins/hls-hlint-plugin/hls-hlint-plugin.cabal
+++ b/plugins/hls-hlint-plugin/hls-hlint-plugin.cabal
@@ -1,4 +1,4 @@
-cabal-version: 2.2
+cabal-version: 2.4
 name:          hls-hlint-plugin
 version:       1.0.1.1
 synopsis:      Hlint integration plugin with Haskell Language Server
@@ -8,10 +8,17 @@ description:
 license:       Apache-2.0
 license-file:  LICENSE
 author:        The Haskell IDE Team
-maintainer:    alan.zimm@gmail.com
+maintainer:    atreyu.bbb@gmail.com
 copyright:     The Haskell IDE Team
 category:      Development
 build-type:    Simple
+extra-source-files:
+  LICENSE
+  test/testdata/**/*.yaml
+  -- this one is not matched by the previous glob
+  test/testdata/ignore/.hlint.yaml
+  test/testdata/**/*.hs
+  test/testdata/**/*.h
 
 flag pedantic
   description: Enable -Werror
@@ -101,3 +108,21 @@ library
   default-extensions:
     DataKinds
     TypeOperators
+
+test-suite tests
+  type:             exitcode-stdio-1.0
+  default-language: Haskell2010
+  hs-source-dirs:   test
+  main-is:          Main.hs
+  ghc-options:      -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      aeson
+    , base
+    , containers
+    , filepath
+    , hls-hlint-plugin
+    , hls-plugin-api
+    , hls-test-utils      >=1.0 && <1.2
+    , lens
+    , lsp-types
+    , text
diff --git a/plugins/hls-hlint-plugin/test/Main.hs b/plugins/hls-hlint-plugin/test/Main.hs
new file mode 100644
index 0000000000..0987a5ef3b
--- /dev/null
+++ b/plugins/hls-hlint-plugin/test/Main.hs
@@ -0,0 +1,287 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Main
+  ( main
+  ) where
+
+import           Control.Lens            ((^.))
+import           Data.Aeson              (toJSON, Value (..), object, (.=))
+import           Data.List               (find)
+import qualified Data.Map                as Map
+import           Data.Maybe              (fromJust, isJust)
+import qualified Data.Text               as T
+import qualified Ide.Plugin.Hlint        as HLint
+import           Ide.Plugin.Config       (hlintOn, Config (..), PluginConfig (..))
+import qualified Language.LSP.Types.Lens as L
+import           System.FilePath         ((</>))
+import           Test.Hls
+import qualified Ide.Plugin.Config as Plugin
+
+main :: IO ()
+main = defaultTestRunner tests
+
+hlintPlugin :: PluginDescriptor IdeState
+hlintPlugin = HLint.descriptor "hlint"
+
+tests :: TestTree
+tests = testGroup "hlint" [
+      suggestionsTests
+    , configTests
+    ]
+
+suggestionsTests :: TestTree
+suggestionsTests =
+  testGroup "hlint suggestions" [
+    testCase "provides 3.8 code actions including apply all" $ runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        diags@(reduceDiag:_) <- waitForDiagnosticsFromSource doc "hlint"
+
+        liftIO $ do
+            length diags @?= 2 -- "Eta Reduce" and "Redundant Id"
+            reduceDiag ^. L.range @?= Range (Position 1 0) (Position 1 12)
+            reduceDiag ^. L.severity @?= Just DsInfo
+            reduceDiag ^. L.code @?= Just (InR "refact:Eta reduce")
+            reduceDiag ^. L.source @?= Just "hlint"
+
+        cas <- map fromAction <$> getAllCodeActions doc
+
+        let applyAll = find (\ca -> "Apply all hints" `T.isSuffixOf` (ca ^. L.title)) cas
+        let redId = find (\ca -> "Redundant id" `T.isSuffixOf` (ca ^. L.title)) cas
+        let redEta = find (\ca -> "Eta reduce" `T.isSuffixOf` (ca ^. L.title)) cas
+
+        liftIO $ isJust applyAll @? "There is 'Apply all hints' code action"
+        liftIO $ isJust redId @? "There is 'Redundant id' code action"
+        liftIO $ isJust redEta @? "There is 'Eta reduce' code action"
+
+        executeCodeAction (fromJust redId)
+
+        contents <- skipManyTill anyMessage $ getDocumentEdit doc
+        liftIO $ contents @?= "main = undefined\nfoo x = x\n"
+
+    , testCase "falls back to pre 3.8 code actions" $ runSessionWithServer' [hlintPlugin] def def noLiteralCaps "test/testdata" $ do
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+
+        _ <- waitForDiagnosticsFromSource doc "hlint"
+
+        cars <- getAllCodeActions doc
+        etaReduce <- liftIO $ inspectCommand cars ["Eta reduce"]
+
+        executeCommand etaReduce
+
+        contents <- skipManyTill anyMessage $ getDocumentEdit doc
+        liftIO $ contents @?= "main = undefined\nfoo = id\n"
+
+    , testCase "changing document contents updates hlint diagnostics" $ runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        testHlintDiagnostics doc
+
+        let change = TextDocumentContentChangeEvent
+                        (Just (Range (Position 1 8) (Position 1 12)))
+                         Nothing "x"
+        changeDoc doc [change]
+        expectNoMoreDiagnostics 3 doc "hlint"
+
+        let change' = TextDocumentContentChangeEvent
+                        (Just (Range (Position 1 8) (Position 1 12)))
+                         Nothing "id x"
+        changeDoc doc [change']
+        testHlintDiagnostics doc
+
+    , knownBrokenForGhcVersions [GHC88, GHC86] "hlint doesn't take in account cpp flag as ghc -D argument" $
+      testCase "hlint diagnostics works with CPP via ghc -XCPP argument (#554)" $ runHlintSession "cpp" $ do
+        doc <- openDoc "ApplyRefact3.hs" "haskell"
+        testHlintDiagnostics doc
+
+    , knownBrokenForGhcVersions [GHC88, GHC86] "hlint doesn't take in account cpp flag as ghc -D argument" $
+      testCase "hlint diagnostics works with CPP via language pragma (#554)" $ runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact3.hs" "haskell"
+        testHlintDiagnostics doc
+
+    , testCase "hlint diagnostics works with CPP via -XCPP argument and flag via #include header (#554)" $ runHlintSession "cpp" $ do
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        testHlintDiagnostics doc
+
+    , testCase "apply-refact works with -XLambdaCase argument (#590)" $ runHlintSession "lambdacase" $ do
+        testRefactor "ApplyRefact1.hs" "Redundant bracket"
+            expectedLambdaCase
+
+    , testCase "apply-refact works with -XTypeApplications argument (#1242)" $ runHlintSession "typeapps" $ do
+        testRefactor "ApplyRefact1.hs" "Redundant bracket"
+            expectedTypeApp
+
+    , testCase "apply hints works with LambdaCase via language pragma" $ runHlintSession "" $ do
+        testRefactor "ApplyRefact1.hs" "Redundant bracket"
+            ("{-# LANGUAGE LambdaCase #-}" : expectedLambdaCase)
+
+    , expectFailBecause "apply-refact doesn't work with cpp" $
+      testCase "apply hints works with CPP via -XCPP argument" $ runHlintSession "cpp" $ do
+        testRefactor "ApplyRefact3.hs" "Redundant bracket"
+            expectedCPP
+
+    , expectFailBecause "apply-refact doesn't work with cpp" $
+      testCase "apply hints works with CPP via language pragma" $ runHlintSession "" $ do
+        testRefactor "ApplyRefact3.hs" "Redundant bracket"
+            ("{-# LANGUAGE CPP #-}" : expectedCPP)
+
+    , testCase "hlint diagnostics ignore hints honouring .hlint.yaml" $ runHlintSession "ignore" $ do
+        doc <- openDoc "ApplyRefact.hs" "haskell"
+        expectNoMoreDiagnostics 3 doc "hlint"
+
+    , testCase "hlint diagnostics ignore hints honouring ANN annotations" $ runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact4.hs" "haskell"
+        expectNoMoreDiagnostics 3 doc "hlint"
+
+    , knownBrokenForGhcVersions [GHC810, GHC90] "hlint plugin doesn't honour HLINT annotations (#838)" $
+      testCase "hlint diagnostics ignore hints honouring HLINT annotations" $ runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact5.hs" "haskell"
+        expectNoMoreDiagnostics 3 doc "hlint"
+
+    , testCase "apply-refact preserve regular comments" $ runHlintSession "" $ do
+        testRefactor "ApplyRefact6.hs" "Redundant bracket" expectedComments
+
+    , testCase "applyAll is shown only when there is at least one diagnostic in range" $  runHlintSession "" $ do
+        doc <- openDoc "ApplyRefact8.hs" "haskell"
+        _ <- waitForDiagnosticsFromSource doc "hlint"
+
+        firstLine <- map fromAction <$> getCodeActions doc (mkRange 0 0 0 0)
+        secondLine <- map fromAction <$> getCodeActions doc (mkRange 1 0 1 0)
+        thirdLine <- map fromAction <$> getCodeActions doc (mkRange 2 0 2 0)
+        multiLine <- map fromAction <$> getCodeActions doc (mkRange 0 0 2 0)
+
+        let hasApplyAll = isJust . find (\ca -> "Apply all hints" `T.isSuffixOf` (ca ^. L.title))
+
+        liftIO $ hasApplyAll firstLine @? "Missing apply all code action"
+        liftIO $ hasApplyAll secondLine @? "Missing apply all code action"
+        liftIO $ not (hasApplyAll thirdLine) @? "Unexpected apply all code action"
+        liftIO $ hasApplyAll multiLine @? "Missing apply all code action"
+    ]
+    where
+        testRefactor file caTitle expected = do
+            doc <- openDoc file "haskell"
+            testHlintDiagnostics doc
+
+            cas <- map fromAction <$> getAllCodeActions doc
+            let ca = find (\ca -> caTitle `T.isSuffixOf` (ca ^. L.title)) cas
+            liftIO $ isJust ca @? ("There is '" ++ T.unpack caTitle ++"' code action")
+
+            executeCodeAction (fromJust ca)
+
+            contents <- skipManyTill anyMessage $ getDocumentEdit doc
+            liftIO $ contents @?= T.unlines expected
+
+        expectedLambdaCase = [ "module ApplyRefact1 where", ""
+                             , "f = \\case \"true\" -> True"
+                             , "          _ -> False"
+                             ]
+        expectedCPP =        [ "module ApplyRefact3 where", ""
+                             , "#ifdef FLAG"
+                             , "f = 1"
+                             , "#else"
+                             , "g = 2"
+                             , "#endif", ""
+                             ]
+        expectedComments =   [ "-- comment before header"
+                             , "module ApplyRefact6 where", ""
+                             , "{-# standalone annotation #-}", ""
+                             , "-- standalone comment", ""
+                             , "-- | haddock comment"
+                             , "f = {- inline comment -}{- inline comment inside refactored code -} 1 -- ending comment", ""
+                             , "-- final comment"
+                             ]
+        expectedTypeApp =    [ "module ApplyRefact1 where", ""
+                             , "a = id @Int 1"
+                             ]
+
+configTests :: TestTree
+configTests = testGroup "hlint plugin config" [
+
+      testCase "changing hlintOn configuration enables or disables hlint diagnostics" $ runHlintSession "" $ do
+        let config = def { hlintOn = True }
+        sendConfigurationChanged (toJSON config)
+
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        testHlintDiagnostics doc
+
+        let config' = def { hlintOn = False }
+        sendConfigurationChanged (toJSON config')
+
+        diags' <- waitForDiagnosticsFrom doc
+
+        liftIO $ noHlintDiagnostics diags'
+
+    , testCase "changing hlint plugin configuration enables or disables hlint diagnostics" $ runHlintSession "" $ do
+        let config = def { hlintOn = True }
+        sendConfigurationChanged (toJSON config)
+
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        testHlintDiagnostics doc
+
+        let config' = pluginGlobalOn config "hlint" False
+        sendConfigurationChanged (toJSON config')
+
+        diags' <- waitForDiagnosticsFrom doc
+
+        liftIO $ noHlintDiagnostics diags'
+
+    , testCase "adding hlint flags to plugin configuration removes hlint diagnostics" $ runHlintSession "" $ do
+        let config = def { hlintOn = True }
+        sendConfigurationChanged (toJSON config)
+
+        doc <- openDoc "ApplyRefact2.hs" "haskell"
+        testHlintDiagnostics doc
+
+        let config' = hlintConfigWithFlags ["--ignore=Redundant id", "--hint=test-hlint-config.yaml"]
+        sendConfigurationChanged (toJSON config')
+
+        diags' <- waitForDiagnosticsFrom doc
+
+        liftIO $ noHlintDiagnostics diags'
+
+    , testCase "adding hlint flags to plugin configuration adds hlint diagnostics" $ runHlintSession "" $ do
+        let config = def { hlintOn = True }
+        sendConfigurationChanged (toJSON config)
+
+        doc <- openDoc "ApplyRefact7.hs" "haskell"
+
+        expectNoMoreDiagnostics 3 doc "hlint"
+
+        let config' = hlintConfigWithFlags ["--with-group=generalise"]
+        sendConfigurationChanged (toJSON config')
+
+        diags' <- waitForDiagnosticsFromSource doc "hlint"
+        d <- liftIO $ inspectDiagnostic diags' ["Use <>"]
+
+        liftIO $ do
+            length diags' @?= 1
+            d ^. L.range @?= Range (Position 1 10) (Position 1 21)
+            d ^. L.severity @?= Just DsInfo
+    ]
+
+runHlintSession :: FilePath -> Session a -> IO a
+runHlintSession subdir  =
+    failIfSessionTimeout . runSessionWithServer hlintPlugin ("test/testdata" </> subdir)
+
+noHlintDiagnostics :: [Diagnostic] -> Assertion
+noHlintDiagnostics diags =
+    Just "hlint" `notElem` map (^. L.source) diags @? "There are no hlint diagnostics"
+
+testHlintDiagnostics :: TextDocumentIdentifier -> Session ()
+testHlintDiagnostics doc = do
+    diags <- waitForDiagnosticsFromSource doc "hlint"
+    liftIO $ length diags > 0 @? "There are hlint diagnostics"
+
+pluginGlobalOn :: Config -> T.Text -> Bool -> Config
+pluginGlobalOn config pid state = config'
+  where
+      pluginConfig = def { plcGlobalOn = state }
+      config' = def { plugins = Map.insert pid pluginConfig (plugins config) }
+
+hlintConfigWithFlags :: [T.Text] -> Config
+hlintConfigWithFlags flags =
+  def
+    { hlintOn = True
+    , Plugin.plugins = Map.fromList [("hlint",
+        def { Plugin.plcConfig = unObject $ object ["flags" .= flags] }
+    )] }
+  where
+    unObject (Object obj) = obj
+    unObject _            = undefined
diff --git a/test/testdata/hlint/ApplyRefact1.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact1.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact1.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact1.hs
diff --git a/test/testdata/hlint/ApplyRefact2.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact2.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact2.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact2.hs
diff --git a/test/testdata/hlint/ApplyRefact3.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact3.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact3.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact3.hs
diff --git a/test/testdata/hlint/ApplyRefact4.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact4.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact4.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact4.hs
diff --git a/test/testdata/hlint/ApplyRefact5.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact5.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact5.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact5.hs
diff --git a/test/testdata/hlint/ApplyRefact6.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact6.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact6.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact6.hs
diff --git a/test/testdata/hlint/ApplyRefact7.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact7.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact7.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact7.hs
diff --git a/test/testdata/hlint/ApplyRefact8.hs b/plugins/hls-hlint-plugin/test/testdata/ApplyRefact8.hs
similarity index 100%
rename from test/testdata/hlint/ApplyRefact8.hs
rename to plugins/hls-hlint-plugin/test/testdata/ApplyRefact8.hs
diff --git a/test/testdata/hlint/cpp/ApplyRefact2.hs b/plugins/hls-hlint-plugin/test/testdata/cpp/ApplyRefact2.hs
similarity index 100%
rename from test/testdata/hlint/cpp/ApplyRefact2.hs
rename to plugins/hls-hlint-plugin/test/testdata/cpp/ApplyRefact2.hs
diff --git a/test/testdata/hlint/cpp/ApplyRefact3.hs b/plugins/hls-hlint-plugin/test/testdata/cpp/ApplyRefact3.hs
similarity index 100%
rename from test/testdata/hlint/cpp/ApplyRefact3.hs
rename to plugins/hls-hlint-plugin/test/testdata/cpp/ApplyRefact3.hs
diff --git a/test/testdata/hlint/cpp/hie.yaml b/plugins/hls-hlint-plugin/test/testdata/cpp/hie.yaml
similarity index 100%
rename from test/testdata/hlint/cpp/hie.yaml
rename to plugins/hls-hlint-plugin/test/testdata/cpp/hie.yaml
diff --git a/test/testdata/hlint/cpp/test.h b/plugins/hls-hlint-plugin/test/testdata/cpp/test.h
similarity index 100%
rename from test/testdata/hlint/cpp/test.h
rename to plugins/hls-hlint-plugin/test/testdata/cpp/test.h
diff --git a/test/testdata/hlint/hie.yaml b/plugins/hls-hlint-plugin/test/testdata/hie.yaml
similarity index 100%
rename from test/testdata/hlint/hie.yaml
rename to plugins/hls-hlint-plugin/test/testdata/hie.yaml
diff --git a/test/testdata/hlint/ignore/.hlint.yaml b/plugins/hls-hlint-plugin/test/testdata/ignore/.hlint.yaml
similarity index 100%
rename from test/testdata/hlint/ignore/.hlint.yaml
rename to plugins/hls-hlint-plugin/test/testdata/ignore/.hlint.yaml
diff --git a/test/testdata/hlint/ignore/ApplyRefact.hs b/plugins/hls-hlint-plugin/test/testdata/ignore/ApplyRefact.hs
similarity index 100%
rename from test/testdata/hlint/ignore/ApplyRefact.hs
rename to plugins/hls-hlint-plugin/test/testdata/ignore/ApplyRefact.hs
diff --git a/test/testdata/hlint/ignore/hie.yaml b/plugins/hls-hlint-plugin/test/testdata/ignore/hie.yaml
similarity index 100%
rename from test/testdata/hlint/ignore/hie.yaml
rename to plugins/hls-hlint-plugin/test/testdata/ignore/hie.yaml
diff --git a/test/testdata/hlint/lambdacase/ApplyRefact1.hs b/plugins/hls-hlint-plugin/test/testdata/lambdacase/ApplyRefact1.hs
similarity index 100%
rename from test/testdata/hlint/lambdacase/ApplyRefact1.hs
rename to plugins/hls-hlint-plugin/test/testdata/lambdacase/ApplyRefact1.hs
diff --git a/test/testdata/hlint/lambdacase/hie.yaml b/plugins/hls-hlint-plugin/test/testdata/lambdacase/hie.yaml
similarity index 100%
rename from test/testdata/hlint/lambdacase/hie.yaml
rename to plugins/hls-hlint-plugin/test/testdata/lambdacase/hie.yaml
diff --git a/test/testdata/hlint/test-hlint-config.yaml b/plugins/hls-hlint-plugin/test/testdata/test-hlint-config.yaml
similarity index 100%
rename from test/testdata/hlint/test-hlint-config.yaml
rename to plugins/hls-hlint-plugin/test/testdata/test-hlint-config.yaml
diff --git a/test/testdata/hlint/typeapps/ApplyRefact1.hs b/plugins/hls-hlint-plugin/test/testdata/typeapps/ApplyRefact1.hs
similarity index 100%
rename from test/testdata/hlint/typeapps/ApplyRefact1.hs
rename to plugins/hls-hlint-plugin/test/testdata/typeapps/ApplyRefact1.hs
diff --git a/test/testdata/hlint/typeapps/hie.yaml b/plugins/hls-hlint-plugin/test/testdata/typeapps/hie.yaml
similarity index 100%
rename from test/testdata/hlint/typeapps/hie.yaml
rename to plugins/hls-hlint-plugin/test/testdata/typeapps/hie.yaml
diff --git a/test/functional/Completion.hs b/test/functional/Completion.hs
index 94faa05f1e..baabbae830 100644
--- a/test/functional/Completion.hs
+++ b/test/functional/Completion.hs
@@ -253,8 +253,7 @@ snippetTests = testGroup "snippets" [
 
         let config = object ["haskell" .= object ["plugin" .= object ["ghcide-completions" .= object ["config" .= object ["snippetsOn" .= False]]]]]
 
-        sendNotification SWorkspaceDidChangeConfiguration
-                        (DidChangeConfigurationParams config)
+        sendConfigurationChanged config
 
         checkNoSnippets doc
 
diff --git a/test/functional/Config.hs b/test/functional/Config.hs
index 6965ffb017..2ad8966034 100644
--- a/test/functional/Config.hs
+++ b/test/functional/Config.hs
@@ -5,10 +5,7 @@ module Config (tests) where
 import           Control.Lens            hiding (List, (.=))
 import           Control.Monad
 import           Data.Aeson
-import qualified Data.Map                as Map
 import qualified Data.Text               as T
-import           Ide.Plugin.Config
-import qualified Ide.Plugin.Config       as Plugin
 import           Language.LSP.Test       as Test
 import qualified Language.LSP.Types.Lens as L
 import           System.FilePath         ((</>))
@@ -19,94 +16,16 @@ import           Test.Hls.Command
 
 tests :: TestTree
 tests = testGroup "plugin config" [
-      -- Note: because the flag is treated generically in the plugin handler, we
-      -- do not have to test each individual plugin
-      hlintTests
-    , configTests
+      -- Note: there are more comprehensive tests over config in hls-hlint-plugin
+      -- TODO: Add generic tests over some example plugin
+      configTests
     ]
 
-hlintTests :: TestTree
-hlintTests = testGroup "hlint plugin enables" [
-
-      testCase "changing hlintOn configuration enables or disables hlint diagnostics" $ runHlintSession "" $ do
-        let config = def { hlintOn = True }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-        let config' = def { hlintOn = False }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config'))
-
-        diags' <- waitForDiagnosticsFrom doc
-
-        liftIO $ noHlintDiagnostics diags'
-
-    , testCase "changing hlint plugin configuration enables or disables hlint diagnostics" $ runHlintSession "" $ do
-        let config = def { hlintOn = True }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-        let config' = pluginGlobalOn config "hlint" False
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config'))
-
-        diags' <- waitForDiagnosticsFrom doc
-
-        liftIO $ noHlintDiagnostics diags'
-
-    , testCase "adding hlint flags to plugin configuration removes hlint diagnostics" $ runHlintSession "" $ do
-        let config = def { hlintOn = True }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-        let config' = hlintConfigWithFlags ["--ignore=Redundant id", "--hint=test-hlint-config.yaml"]
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config'))
-
-        diags' <- waitForDiagnosticsFrom doc
-
-        liftIO $ noHlintDiagnostics diags'
-
-    , testCase "adding hlint flags to plugin configuration adds hlint diagnostics" $ runHlintSession "" $ do
-        let config = def { hlintOn = True }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-        doc <- openDoc "ApplyRefact7.hs" "haskell"
-
-        expectNoMoreDiagnostics 3 doc "hlint"
-
-        let config' = hlintConfigWithFlags ["--with-group=generalise"]
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config'))
-
-        diags' <- waitForDiagnosticsFromSource doc "hlint"
-        d <- liftIO $ inspectDiagnostic diags' ["Use <>"]
-
-        liftIO $ do
-            length diags' @?= 1
-            d ^. L.range @?= Range (Position 1 10) (Position 1 21)
-            d ^. L.severity @?= Just DsInfo
-    ]
-    where
-        runHlintSession :: FilePath -> Session a -> IO a
-        runHlintSession subdir  =
-            failIfSessionTimeout . runSession hlsCommand fullCaps ("test/testdata/hlint" </> subdir)
-
-        noHlintDiagnostics :: [Diagnostic] -> Assertion
-        noHlintDiagnostics diags =
-            Just "hlint" `notElem` map (^. L.source) diags @? "There are no hlint diagnostics"
-
-        testHlintDiagnostics doc = do
-            diags <- waitForDiagnosticsFromSource doc "hlint"
-            liftIO $ length diags > 0 @? "There are hlint diagnostics"
-
 configTests :: TestTree
 configTests = testGroup "config parsing" [
       testCase "empty object as user configuration should not send error logMessage" $ runConfigSession "" $ do
         let config = object []
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
+        sendConfigurationChanged (toJSON config)
 
         -- Send custom request so server returns a response to prevent blocking
         void $ sendNotification (SCustomMethod "non-existent-method") Null
@@ -121,20 +40,3 @@ configTests = testGroup "config parsing" [
         runConfigSession :: FilePath -> Session a -> IO a
         runConfigSession subdir  =
             failIfSessionTimeout . runSession hlsCommand fullCaps ("test/testdata" </> subdir)
-
-pluginGlobalOn :: Config -> T.Text -> Bool -> Config
-pluginGlobalOn config pid state = config'
-  where
-      pluginConfig = def { plcGlobalOn = state }
-      config' = def { plugins = Map.insert pid pluginConfig (plugins config) }
-
-hlintConfigWithFlags :: [T.Text] -> Config
-hlintConfigWithFlags flags =
-  def
-    { hlintOn = True
-    , Plugin.plugins = Map.fromList [("hlint",
-        def { Plugin.plcConfig = unObject $ object ["flags" .= flags] }
-    )] }
-  where
-    unObject (Object obj) = obj
-    unObject _            = undefined
diff --git a/test/functional/Diagnostic.hs b/test/functional/Diagnostic.hs
index bfe304d99e..06d6bf5e03 100644
--- a/test/functional/Diagnostic.hs
+++ b/test/functional/Diagnostic.hs
@@ -21,21 +21,9 @@ tests = testGroup "diagnostics providers" [
 
 basicTests :: TestTree
 basicTests = testGroup "Diagnostics work" [
-    testCase "hlint produces diagnostics" $
-        runSession hlsCommand fullCaps "test/testdata/hlint" $ do
-            doc <- openDoc "ApplyRefact2.hs" "haskell"
-            diags <- waitForDiagnosticsFromSource doc "hlint"
-            reduceDiag <- liftIO $ inspectDiagnostic diags ["Eta reduce"]
-            redundantID <- liftIO $ inspectDiagnostic diags ["Redundant id"]
-            liftIO $ do
-                length diags @?= 2
-                reduceDiag ^. LSP.range @?= Range (Position 1 0) (Position 1 12)
-                reduceDiag ^. LSP.severity @?= Just DsInfo
-                redundantID ^. LSP.severity @?= Just DsInfo
-
-    , testCase "example plugin produces diagnostics" $
-        runSession hlsCommandExamplePlugin fullCaps "test/testdata/hlint" $ do
-            doc <- openDoc "ApplyRefact2.hs" "haskell"
+    testCase "example plugin produces diagnostics" $
+        runSession hlsCommandExamplePlugin fullCaps "test/testdata/diagnostics" $ do
+            doc <- openDoc "Foo.hs" "haskell"
             diags <- waitForDiagnosticsFromSource doc "example2"
             reduceDiag <- liftIO $ inspectDiagnostic diags ["example2 diagnostic, hello world"]
             liftIO $ do
@@ -58,7 +46,7 @@ saveTests = testGroup  "only diagnostics on save" [
     ignoreTestBecause "diagnosticsOnChange parameter is not supported right now" $ testCase "Respects diagnosticsOnChange setting" $
         runSession hlsCommandExamplePlugin codeActionSupportCaps "test/testdata" $ do
             let config = Data.Default.def { diagnosticsOnChange = False } :: Config
-            sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
+            sendConfigurationChanged (toJSON config)
             doc <- openDoc "Hover.hs" "haskell"
             diags <- waitForDiagnosticsFrom doc
 
diff --git a/test/functional/Format.hs b/test/functional/Format.hs
index 4620f4fdd8..43e9366843 100644
--- a/test/functional/Format.hs
+++ b/test/functional/Format.hs
@@ -56,15 +56,15 @@ providerTests = testGroup "formatting provider" [
 
         doc <- openDoc "Format.hs" "haskell"
 
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "ormolu"))
+        sendConfigurationChanged (formatLspConfig "ormolu")
         formatDoc doc (FormattingOptions 2 True Nothing Nothing Nothing)
         documentContents doc >>= liftIO . (@?= formattedOrmolu)
 
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "floskell"))
+        sendConfigurationChanged (formatLspConfig "floskell")
         formatDoc doc (FormattingOptions 2 True Nothing Nothing Nothing)
         documentContents doc >>= liftIO . (@?= formattedFloskell)
 
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "ormolu"))
+        sendConfigurationChanged (formatLspConfig "ormolu")
         formatDoc doc (FormattingOptions 2 True Nothing Nothing Nothing)
         documentContents doc >>= liftIO . (@?= formattedOrmoluPostFloskell)
     , requiresOrmoluPlugin . requiresFloskellPlugin $ testCase "supports both new and old configuration sections" $ runSession hlsCommand fullCaps "test/testdata/format" $ do
@@ -73,11 +73,11 @@ providerTests = testGroup "formatting provider" [
 
        doc <- openDoc "Format.hs" "haskell"
 
-       sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfigOld "ormolu"))
+       sendConfigurationChanged (formatLspConfigOld "ormolu")
        formatDoc doc (FormattingOptions 2 True Nothing Nothing Nothing)
        documentContents doc >>= liftIO . (@?= formattedOrmolu)
 
-       sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfigOld "floskell"))
+       sendConfigurationChanged (formatLspConfigOld "floskell")
        formatDoc doc (FormattingOptions 2 True Nothing Nothing Nothing)
        documentContents doc >>= liftIO . (@?= formattedFloskell)
     ]
diff --git a/test/functional/FunctionalCodeAction.hs b/test/functional/FunctionalCodeAction.hs
index 6c0bd95c4a..cf368b0613 100644
--- a/test/functional/FunctionalCodeAction.hs
+++ b/test/functional/FunctionalCodeAction.hs
@@ -14,20 +14,17 @@ import           Data.Maybe
 import qualified Data.Text                       as T
 import           Ide.Plugin.Config
 import           Language.LSP.Test               as Test
-import qualified Language.LSP.Types.Capabilities as C
 import qualified Language.LSP.Types.Lens         as L
 import           Test.Hls
 import           Test.Hspec.Expectations
 
-import           System.FilePath                 ((</>))
 import           Test.Hls.Command
 
 {-# ANN module ("HLint: ignore Reduce duplication"::String) #-}
 
 tests :: TestTree
 tests = testGroup "code actions" [
-      hlintTests
-    , importTests
+      importTests
     , packageTests
     , redundantImportTests
     , renameTests
@@ -36,194 +33,6 @@ tests = testGroup "code actions" [
     , unusedTermTests
     ]
 
-
-hlintTests :: TestTree
-hlintTests = testGroup "hlint suggestions" [
-    testCase "provides 3.8 code actions including apply all" $ runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        diags@(reduceDiag:_) <- waitForDiagnosticsFromSource doc "hlint"
-
-        liftIO $ do
-            length diags @?= 2 -- "Eta Reduce" and "Redundant Id"
-            reduceDiag ^. L.range @?= Range (Position 1 0) (Position 1 12)
-            reduceDiag ^. L.severity @?= Just DsInfo
-            reduceDiag ^. L.code @?= Just (InR "refact:Eta reduce")
-            reduceDiag ^. L.source @?= Just "hlint"
-
-        cas <- map fromAction <$> getAllCodeActions doc
-
-        let applyAll = find (\ca -> "Apply all hints" `T.isSuffixOf` (ca ^. L.title)) cas
-        let redId = find (\ca -> "Redundant id" `T.isSuffixOf` (ca ^. L.title)) cas
-        let redEta = find (\ca -> "Eta reduce" `T.isSuffixOf` (ca ^. L.title)) cas
-
-        liftIO $ isJust applyAll @? "There is 'Apply all hints' code action"
-        liftIO $ isJust redId @? "There is 'Redundant id' code action"
-        liftIO $ isJust redEta @? "There is 'Eta reduce' code action"
-
-        executeCodeAction (fromJust redId)
-
-        contents <- skipManyTill anyMessage $ getDocumentEdit doc
-        liftIO $ contents @?= "main = undefined\nfoo x = x\n"
-
-    , testCase "falls back to pre 3.8 code actions" $ runSession hlsCommand noLiteralCaps "test/testdata/hlint" $ do
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-
-        _ <- waitForDiagnosticsFromSource doc "hlint"
-
-        cars <- getAllCodeActions doc
-        etaReduce <- liftIO $ inspectCommand cars ["Eta reduce"]
-
-        executeCommand etaReduce
-
-        contents <- skipManyTill anyMessage $ getDocumentEdit doc
-        liftIO $ contents @?= "main = undefined\nfoo = id\n"
-
-    , testCase "changing configuration enables or disables hlint diagnostics" $ runHlintSession "" $ do
-        let config = def { hlintOn = True }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-        let config' = def { hlintOn = False }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config'))
-
-        diags' <- waitForDiagnosticsFrom doc
-
-        liftIO $ noHlintDiagnostics diags'
-
-    , testCase "changing document contents updates hlint diagnostics" $ runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-        let change = TextDocumentContentChangeEvent
-                        (Just (Range (Position 1 8) (Position 1 12)))
-                         Nothing "x"
-        changeDoc doc [change]
-        expectNoMoreDiagnostics 3 doc "hlint"
-
-        let change' = TextDocumentContentChangeEvent
-                        (Just (Range (Position 1 8) (Position 1 12)))
-                         Nothing "id x"
-        changeDoc doc [change']
-        testHlintDiagnostics doc
-
-    , knownBrokenForGhcVersions [GHC88, GHC86] "hlint doesn't take in account cpp flag as ghc -D argument" $
-      testCase "hlint diagnostics works with CPP via ghc -XCPP argument (#554)" $ runHlintSession "cpp" $ do
-        doc <- openDoc "ApplyRefact3.hs" "haskell"
-        testHlintDiagnostics doc
-
-    , knownBrokenForGhcVersions [GHC88, GHC86] "hlint doesn't take in account cpp flag as ghc -D argument" $
-      testCase "hlint diagnostics works with CPP via language pragma (#554)" $ runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact3.hs" "haskell"
-        testHlintDiagnostics doc
-
-    , testCase "hlint diagnostics works with CPP via -XCPP argument and flag via #include header (#554)" $ runHlintSession "cpp" $ do
-        doc <- openDoc "ApplyRefact2.hs" "haskell"
-        testHlintDiagnostics doc
-
-    , testCase "apply-refact works with -XLambdaCase argument (#590)" $ runHlintSession "lambdacase" $ do
-        testRefactor "ApplyRefact1.hs" "Redundant bracket"
-            expectedLambdaCase
-
-    , testCase "apply-refact works with -XTypeApplications argument (#1242)" $ runHlintSession "typeapps" $ do
-        testRefactor "ApplyRefact1.hs" "Redundant bracket"
-            expectedTypeApp
-
-    , testCase "apply hints works with LambdaCase via language pragma" $ runHlintSession "" $ do
-        testRefactor "ApplyRefact1.hs" "Redundant bracket"
-            ("{-# LANGUAGE LambdaCase #-}" : expectedLambdaCase)
-
-    , expectFailBecause "apply-refact doesn't work with cpp" $
-      testCase "apply hints works with CPP via -XCPP argument" $ runHlintSession "cpp" $ do
-        testRefactor "ApplyRefact3.hs" "Redundant bracket"
-            expectedCPP
-
-    , expectFailBecause "apply-refact doesn't work with cpp" $
-      testCase "apply hints works with CPP via language pragma" $ runHlintSession "" $ do
-        testRefactor "ApplyRefact3.hs" "Redundant bracket"
-            ("{-# LANGUAGE CPP #-}" : expectedCPP)
-
-    , testCase "hlint diagnostics ignore hints honouring .hlint.yaml" $ runHlintSession "ignore" $ do
-        doc <- openDoc "ApplyRefact.hs" "haskell"
-        expectNoMoreDiagnostics 3 doc "hlint"
-
-    , testCase "hlint diagnostics ignore hints honouring ANN annotations" $ runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact4.hs" "haskell"
-        expectNoMoreDiagnostics 3 doc "hlint"
-
-    , knownBrokenForGhcVersions [GHC810, GHC90] "hlint plugin doesn't honour HLINT annotations (#838)" $
-      testCase "hlint diagnostics ignore hints honouring HLINT annotations" $ runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact5.hs" "haskell"
-        expectNoMoreDiagnostics 3 doc "hlint"
-
-    , testCase "apply-refact preserve regular comments" $ runHlintSession "" $ do
-        testRefactor "ApplyRefact6.hs" "Redundant bracket" expectedComments
-
-    , testCase "applyAll is shown only when there is at least one diagnostic in range" $  runHlintSession "" $ do
-        doc <- openDoc "ApplyRefact8.hs" "haskell"
-        _ <- waitForDiagnosticsFromSource doc "hlint"
-
-        firstLine <- map fromAction <$> getCodeActions doc (mkRange 0 0 0 0)
-        secondLine <- map fromAction <$> getCodeActions doc (mkRange 1 0 1 0)
-        thirdLine <- map fromAction <$> getCodeActions doc (mkRange 2 0 2 0)
-        multiLine <- map fromAction <$> getCodeActions doc (mkRange 0 0 2 0)
-
-        let hasApplyAll = isJust . find (\ca -> "Apply all hints" `T.isSuffixOf` (ca ^. L.title))
-
-        liftIO $ hasApplyAll firstLine @? "Missing apply all code action"
-        liftIO $ hasApplyAll secondLine @? "Missing apply all code action"
-        liftIO $ not (hasApplyAll thirdLine) @? "Unexpected apply all code action"
-        liftIO $ hasApplyAll multiLine @? "Missing apply all code action"
-    ]
-    where
-        runHlintSession :: FilePath -> Session a -> IO a
-        runHlintSession subdir  =
-            failIfSessionTimeout . runSession hlsCommand fullCaps ("test/testdata/hlint" </> subdir)
-
-        noHlintDiagnostics :: [Diagnostic] -> Assertion
-        noHlintDiagnostics diags =
-            Just "hlint" `notElem` map (^. L.source) diags @? "There are no hlint diagnostics"
-
-        testHlintDiagnostics doc = do
-            diags <- waitForDiagnosticsFromSource doc "hlint"
-            liftIO $ length diags > 0 @? "There are hlint diagnostics"
-
-        testRefactor file caTitle expected = do
-            doc <- openDoc file "haskell"
-            testHlintDiagnostics doc
-
-            cas <- map fromAction <$> getAllCodeActions doc
-            let ca = find (\ca -> caTitle `T.isSuffixOf` (ca ^. L.title)) cas
-            liftIO $ isJust ca @? ("There is '" ++ T.unpack caTitle ++"' code action")
-
-            executeCodeAction (fromJust ca)
-
-            contents <- skipManyTill anyMessage $ getDocumentEdit doc
-            liftIO $ contents @?= T.unlines expected
-
-        expectedLambdaCase = [ "module ApplyRefact1 where", ""
-                             , "f = \\case \"true\" -> True"
-                             , "          _ -> False"
-                             ]
-        expectedCPP =        [ "module ApplyRefact3 where", ""
-                             , "#ifdef FLAG"
-                             , "f = 1"
-                             , "#else"
-                             , "g = 2"
-                             , "#endif", ""
-                             ]
-        expectedComments =   [ "-- comment before header"
-                             , "module ApplyRefact6 where", ""
-                             , "{-# standalone annotation #-}", ""
-                             , "-- standalone comment", ""
-                             , "-- | haddock comment"
-                             , "f = {- inline comment -}{- inline comment inside refactored code -} 1 -- ending comment", ""
-                             , "-- final comment"
-                             ]
-        expectedTypeApp =    [ "module ApplyRefact1 where", ""
-                             , "a = id @Int 1"
-                             ]
 renameTests :: TestTree
 renameTests = testGroup "rename suggestions" [
     testCase "works" $ runSession hlsCommand noLiteralCaps "test/testdata" $ do
@@ -269,7 +78,7 @@ importTests = testGroup "import suggestions" [
         doc <- openDoc "CodeActionImport.hs" "haskell"
         -- No Formatting:
         let config = def { formattingProvider = "none" }
-        sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
+        sendConfigurationChanged (toJSON config)
 
         (diag:_) <- waitForDiagnosticsFrom doc
         liftIO $ diag ^. L.message @?= "Variable not in scope: when :: Bool -> IO () -> IO ()"
@@ -553,17 +362,6 @@ expectFailIfGhc9 reason =
 
 disableWingman :: Session ()
 disableWingman =
-  sendConfigurationChanged $ def
+  sendConfigurationChanged $ toJSON $ def
     { plugins = M.fromList [ ("tactics", def { plcGlobalOn = False }) ]
     }
-
-
-sendConfigurationChanged :: Config -> Session ()
-sendConfigurationChanged config =
-  sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
-
-noLiteralCaps :: C.ClientCapabilities
-noLiteralCaps = def { C._textDocument = Just textDocumentCaps }
-  where
-    textDocumentCaps = def { C._codeAction = Just codeActionCaps }
-    codeActionCaps = CodeActionClientCapabilities (Just True) Nothing Nothing Nothing Nothing Nothing Nothing
diff --git a/test/functional/FunctionalLiquid.hs b/test/functional/FunctionalLiquid.hs
index 77a553f7ad..06a489c523 100644
--- a/test/functional/FunctionalLiquid.hs
+++ b/test/functional/FunctionalLiquid.hs
@@ -19,7 +19,7 @@ tests = testGroup "liquid haskell diagnostics" [
             doc <- openDoc "liquid/Evens.hs" "haskell"
 
             let config = def { liquidOn  = True, hlintOn = False }
-            sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
+            sendConfigurationChanged (toJSON config)
 
             diags <- waitForDiagnosticsFromSource doc "liquid"
             d <- liftIO $ inspectDiagnostic diags ["Liquid Type Mismatch"]
diff --git a/test/functional/Progress.hs b/test/functional/Progress.hs
index a4b9ac4fa1..1f8c987cf0 100644
--- a/test/functional/Progress.hs
+++ b/test/functional/Progress.hs
@@ -27,9 +27,9 @@ tests =
         "window/workDoneProgress"
         [ testCase "sends indefinite progress notifications" $
             runSession hlsCommand progressCaps "test/testdata" $ do
-                let path = "hlint" </> "ApplyRefact2.hs"
+                let path = "diagnostics" </> "Foo.hs"
                 _ <- openDoc path "haskell"
-                expectProgressReports [pack ("Setting up hlint (for " ++ path ++ ")"), "Processing", "Indexing"]
+                expectProgressReports [pack ("Setting up testdata (for " ++ path ++ ")"), "Processing", "Indexing"]
         , requiresEvalPlugin $ testCase "eval plugin sends progress reports" $
             runSession hlsCommand progressCaps "plugins/hls-eval-plugin/test/testdata" $ do
                 doc <- openDoc "T1.hs" "haskell"
@@ -40,14 +40,14 @@ tests =
                 expectProgressReports ["Evaluating"]
         , requiresOrmoluPlugin $ testCase "ormolu plugin sends progress notifications" $ do
             runSession hlsCommand progressCaps "test/testdata/format" $ do
-                sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "ormolu"))
+                sendConfigurationChanged (formatLspConfig "ormolu")
                 doc <- openDoc "Format.hs" "haskell"
                 expectProgressReports ["Setting up testdata (for Format.hs)", "Processing", "Indexing"]
                 _ <- sendRequest STextDocumentFormatting $ DocumentFormattingParams Nothing doc (FormattingOptions 2 True Nothing Nothing Nothing)
                 expectProgressReports ["Formatting Format.hs"]
         , requiresFourmoluPlugin $ testCase "fourmolu plugin sends progress notifications" $ do
             runSession hlsCommand progressCaps "test/testdata/format" $ do
-                sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "fourmolu"))
+                sendConfigurationChanged (formatLspConfig "fourmolu")
                 doc <- openDoc "Format.hs" "haskell"
                 expectProgressReports ["Setting up testdata (for Format.hs)", "Processing", "Indexing"]
                 _ <- sendRequest STextDocumentFormatting $ DocumentFormattingParams Nothing doc (FormattingOptions 2 True Nothing Nothing Nothing)
@@ -57,7 +57,7 @@ tests =
                 runSession hlsCommand progressCaps "test/testdata" $ do
                     doc <- openDoc "liquid/Evens.hs" "haskell"
                     let config = def{liquidOn = True, hlintOn = False}
-                    sendNotification SWorkspaceDidChangeConfiguration (DidChangeConfigurationParams (toJSON config))
+                    sendConfigurationChanged (toJSON config)
                     sendNotification STextDocumentDidSave (DidSaveTextDocumentParams doc Nothing)
                     expectProgressReports ["Running Liquid Haskell on Evens.hs"]
         ]
diff --git a/test/testdata/cabal-helper/implicit-exe/Setup.hs b/test/testdata/cabal-helper/implicit-exe/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/implicit-exe/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/implicit-exe/cabal.project b/test/testdata/cabal-helper/implicit-exe/cabal.project
deleted file mode 100644
index bfe6289656..0000000000
--- a/test/testdata/cabal-helper/implicit-exe/cabal.project
+++ /dev/null
@@ -1 +0,0 @@
-packages: ./
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/implicit-exe/implicit-exe.cabal b/test/testdata/cabal-helper/implicit-exe/implicit-exe.cabal
deleted file mode 100644
index 3aca1b42fa..0000000000
--- a/test/testdata/cabal-helper/implicit-exe/implicit-exe.cabal
+++ /dev/null
@@ -1,17 +0,0 @@
-cabal-version:       >=1.10
-name:                implicit-exe
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     Lib
-  hs-source-dirs:      src
-  build-depends:       base
-  default-language:    Haskell2010
-
-
-executable implicit-exe
-  main-is:             src/Exe.hs
-  build-depends:       base, implicit-exe
-  default-language:    Haskell2010
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/implicit-exe/src/Exe.hs b/test/testdata/cabal-helper/implicit-exe/src/Exe.hs
deleted file mode 100644
index ed41929e78..0000000000
--- a/test/testdata/cabal-helper/implicit-exe/src/Exe.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-
-import Lib (someFunc)
-
-main = someFunc
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/implicit-exe/src/Lib.hs b/test/testdata/cabal-helper/implicit-exe/src/Lib.hs
deleted file mode 100644
index f51af83e20..0000000000
--- a/test/testdata/cabal-helper/implicit-exe/src/Lib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module Lib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/mono-repo/A/A.cabal b/test/testdata/cabal-helper/mono-repo/A/A.cabal
deleted file mode 100644
index e70b43fc1d..0000000000
--- a/test/testdata/cabal-helper/mono-repo/A/A.cabal
+++ /dev/null
@@ -1,15 +0,0 @@
-cabal-version:       >=1.10
-name:                A
-version:             0.1.0.0
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base
-  default-language:    Haskell2010
-
-executable A
-  main-is:             Main.hs
-  other-modules:       MyLib
-  build-depends:       base, A
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/mono-repo/A/Main.hs b/test/testdata/cabal-helper/mono-repo/A/Main.hs
deleted file mode 100644
index 60d904e8c1..0000000000
--- a/test/testdata/cabal-helper/mono-repo/A/Main.hs
+++ /dev/null
@@ -1,8 +0,0 @@
-module Main where
-
-import qualified MyLib (someFunc)
-
-main :: IO ()
-main = do
-  putStrLn "Hello, Haskell!"
-  MyLib.someFunc
diff --git a/test/testdata/cabal-helper/mono-repo/A/MyLib.hs b/test/testdata/cabal-helper/mono-repo/A/MyLib.hs
deleted file mode 100644
index e657c4403f..0000000000
--- a/test/testdata/cabal-helper/mono-repo/A/MyLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module MyLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/mono-repo/A/Setup.hs b/test/testdata/cabal-helper/mono-repo/A/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/mono-repo/A/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/mono-repo/B/B.cabal b/test/testdata/cabal-helper/mono-repo/B/B.cabal
deleted file mode 100644
index 4093e1d0f6..0000000000
--- a/test/testdata/cabal-helper/mono-repo/B/B.cabal
+++ /dev/null
@@ -1,15 +0,0 @@
-cabal-version:       >=1.10
-name:                B
-version:             0.1.0.0
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base
-  default-language:    Haskell2010
-
-executable B
-  main-is:             Main.hs
-  other-modules:       MyLib
-  build-depends:       base, B
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/mono-repo/B/Main.hs b/test/testdata/cabal-helper/mono-repo/B/Main.hs
deleted file mode 100644
index 60d904e8c1..0000000000
--- a/test/testdata/cabal-helper/mono-repo/B/Main.hs
+++ /dev/null
@@ -1,8 +0,0 @@
-module Main where
-
-import qualified MyLib (someFunc)
-
-main :: IO ()
-main = do
-  putStrLn "Hello, Haskell!"
-  MyLib.someFunc
diff --git a/test/testdata/cabal-helper/mono-repo/B/MyLib.hs b/test/testdata/cabal-helper/mono-repo/B/MyLib.hs
deleted file mode 100644
index e657c4403f..0000000000
--- a/test/testdata/cabal-helper/mono-repo/B/MyLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module MyLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/mono-repo/B/Setup.hs b/test/testdata/cabal-helper/mono-repo/B/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/mono-repo/B/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/mono-repo/C/C.cabal b/test/testdata/cabal-helper/mono-repo/C/C.cabal
deleted file mode 100644
index db5e380f49..0000000000
--- a/test/testdata/cabal-helper/mono-repo/C/C.cabal
+++ /dev/null
@@ -1,9 +0,0 @@
-cabal-version:       >=1.10
-name:                C
-version:             0.1.0.0
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/mono-repo/C/MyLib.hs b/test/testdata/cabal-helper/mono-repo/C/MyLib.hs
deleted file mode 100644
index e657c4403f..0000000000
--- a/test/testdata/cabal-helper/mono-repo/C/MyLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module MyLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/mono-repo/C/Setup.hs b/test/testdata/cabal-helper/mono-repo/C/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/mono-repo/C/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/mono-repo/cabal.project b/test/testdata/cabal-helper/mono-repo/cabal.project
deleted file mode 100644
index cf2eab3e10..0000000000
--- a/test/testdata/cabal-helper/mono-repo/cabal.project
+++ /dev/null
@@ -1,4 +0,0 @@
-packages:
-  ./A/
-  ./B/
-  ./C/
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/multi-source-dirs/Setup.hs b/test/testdata/cabal-helper/multi-source-dirs/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/multi-source-dirs/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/multi-source-dirs/multi-source-dirs.cabal b/test/testdata/cabal-helper/multi-source-dirs/multi-source-dirs.cabal
deleted file mode 100644
index 58568683dd..0000000000
--- a/test/testdata/cabal-helper/multi-source-dirs/multi-source-dirs.cabal
+++ /dev/null
@@ -1,11 +0,0 @@
-cabal-version:       >=1.10
-name:                multi-source-dirs
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     Lib, BetterLib
-  hs-source-dirs:      src, src/input
-  build-depends:       base
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/multi-source-dirs/src/BetterLib.hs b/test/testdata/cabal-helper/multi-source-dirs/src/BetterLib.hs
deleted file mode 100644
index 0784c76d48..0000000000
--- a/test/testdata/cabal-helper/multi-source-dirs/src/BetterLib.hs
+++ /dev/null
@@ -1,5 +0,0 @@
-module BetterLib where
-
-
-foo = 3
-bar = "String"
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/multi-source-dirs/src/input/Lib.hs b/test/testdata/cabal-helper/multi-source-dirs/src/input/Lib.hs
deleted file mode 100644
index 6c37234910..0000000000
--- a/test/testdata/cabal-helper/multi-source-dirs/src/input/Lib.hs
+++ /dev/null
@@ -1,6 +0,0 @@
-module Lib where
-
-foobar = 15
-
-fizbuzz :: Int -> String
-fizbuzz n = "Fizz"
\ No newline at end of file
diff --git a/test/testdata/cabal-helper/simple-cabal/MyLib.hs b/test/testdata/cabal-helper/simple-cabal/MyLib.hs
deleted file mode 100644
index e657c4403f..0000000000
--- a/test/testdata/cabal-helper/simple-cabal/MyLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module MyLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/simple-cabal/Setup.hs b/test/testdata/cabal-helper/simple-cabal/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/simple-cabal/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/simple-cabal/simple-cabal-test.cabal b/test/testdata/cabal-helper/simple-cabal/simple-cabal-test.cabal
deleted file mode 100644
index 3c8be5d868..0000000000
--- a/test/testdata/cabal-helper/simple-cabal/simple-cabal-test.cabal
+++ /dev/null
@@ -1,10 +0,0 @@
-cabal-version:       >=1.10
-name:                simple-cabal-test
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/simple-stack/MyLib.hs b/test/testdata/cabal-helper/simple-stack/MyLib.hs
deleted file mode 100644
index e657c4403f..0000000000
--- a/test/testdata/cabal-helper/simple-stack/MyLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module MyLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/simple-stack/Setup.hs b/test/testdata/cabal-helper/simple-stack/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/simple-stack/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/simple-stack/simple-stack-test.cabal b/test/testdata/cabal-helper/simple-stack/simple-stack-test.cabal
deleted file mode 100644
index 264baebfd1..0000000000
--- a/test/testdata/cabal-helper/simple-stack/simple-stack-test.cabal
+++ /dev/null
@@ -1,10 +0,0 @@
-cabal-version:       >=1.10
-name:                simple-stack-test
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/sub-package/Setup.hs b/test/testdata/cabal-helper/sub-package/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/sub-package/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/sub-package/app/Main.hs b/test/testdata/cabal-helper/sub-package/app/Main.hs
deleted file mode 100644
index 60d904e8c1..0000000000
--- a/test/testdata/cabal-helper/sub-package/app/Main.hs
+++ /dev/null
@@ -1,8 +0,0 @@
-module Main where
-
-import qualified MyLib (someFunc)
-
-main :: IO ()
-main = do
-  putStrLn "Hello, Haskell!"
-  MyLib.someFunc
diff --git a/test/testdata/cabal-helper/sub-package/plugins-api/PluginLib.hs b/test/testdata/cabal-helper/sub-package/plugins-api/PluginLib.hs
deleted file mode 100644
index 55a7098c23..0000000000
--- a/test/testdata/cabal-helper/sub-package/plugins-api/PluginLib.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module PluginLib (someFunc) where
-
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
diff --git a/test/testdata/cabal-helper/sub-package/plugins-api/Setup.hs b/test/testdata/cabal-helper/sub-package/plugins-api/Setup.hs
deleted file mode 100644
index 9a994af677..0000000000
--- a/test/testdata/cabal-helper/sub-package/plugins-api/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/test/testdata/cabal-helper/sub-package/plugins-api/plugins-api.cabal b/test/testdata/cabal-helper/sub-package/plugins-api/plugins-api.cabal
deleted file mode 100644
index 223fa73b95..0000000000
--- a/test/testdata/cabal-helper/sub-package/plugins-api/plugins-api.cabal
+++ /dev/null
@@ -1,10 +0,0 @@
-cabal-version:       >=1.10
-name:                plugins-api
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     PluginLib
-  build-depends:       base
-  default-language:    Haskell2010
diff --git a/test/testdata/cabal-helper/sub-package/src/MyLib.hs b/test/testdata/cabal-helper/sub-package/src/MyLib.hs
deleted file mode 100644
index 53ea5c6332..0000000000
--- a/test/testdata/cabal-helper/sub-package/src/MyLib.hs
+++ /dev/null
@@ -1,6 +0,0 @@
-module MyLib (someFunc) where
-
-import qualified PluginLib as L
-
-someFunc :: IO ()
-someFunc = L.someFunc
diff --git a/test/testdata/cabal-helper/sub-package/sub-package.cabal b/test/testdata/cabal-helper/sub-package/sub-package.cabal
deleted file mode 100644
index ba36f1b4d1..0000000000
--- a/test/testdata/cabal-helper/sub-package/sub-package.cabal
+++ /dev/null
@@ -1,17 +0,0 @@
-cabal-version:       >=1.10
-name:                sub-package
-version:             0.1.0.0
-license-file:        LICENSE
-build-type:          Simple
-
-library
-  exposed-modules:     MyLib
-  build-depends:       base, plugins-api
-  hs-source-dirs:      src
-  default-language:    Haskell2010
-
-executable sub-package
-  main-is:             Main.hs
-  build-depends:       base, sub-package
-  hs-source-dirs:      app
-  default-language:    Haskell2010
diff --git a/test/testdata/diagnostics/Foo.hs b/test/testdata/diagnostics/Foo.hs
new file mode 100644
index 0000000000..d83992f387
--- /dev/null
+++ b/test/testdata/diagnostics/Foo.hs
@@ -0,0 +1,2 @@
+main = undefined
+foo x = id x