diff --git a/hls-class-plugin.cabal b/hls-class-plugin.cabal
--- a/hls-class-plugin.cabal
+++ b/hls-class-plugin.cabal
@@ -1,10 +1,13 @@
-cabal-version:      2.2
+cabal-version:      2.4
 name:               hls-class-plugin
-version:            1.0.0.0
-synopsis:           Class/instance management plugin for Haskell Language Server
+version:            1.0.0.1
+synopsis:
+  Class/instance management plugin for Haskell Language Server
+
 description:
-    Class/instance management plugin for Haskell Language Server.
-    For usage, please see README of HLS on GitHub at <https://github.com/haskell/haskell-language-server#readme>
+  Class/instance management plugin for Haskell Language Server.
+  For usage, please see README of HLS on GitHub at <https://github.com/haskell/haskell-language-server#readme>
+
 license:            Apache-2.0
 license-file:       LICENSE
 author:             Junyoung Clare Jang
@@ -13,24 +16,48 @@
 bug-reports:        https://github.com/haskell/haskell-language-server/issues
 category:           Development
 build-type:         Simple
+extra-source-files:
+  LICENSE
+  test/testdata/*.hs
 
 library
-  exposed-modules:  Ide.Plugin.Class
-  hs-source-dirs:   src
-  build-depends:    aeson
-                  , base           >=4.12 && <5
-                  , containers
-                  , lsp
-                  , hls-plugin-api ^>= 1.0.0.0
-                  , ghc
-                  , ghc-exactprint
-                  , ghcide         ^>= 1.0.0.0
-                  , lens
-                  , shake
-                  , text
-                  , transformers
-                  , unordered-containers
+  exposed-modules:    Ide.Plugin.Class
+  hs-source-dirs:     src
+  build-depends:
+    , aeson
+    , base                  >=4.12    && <5
+    , containers
+    , ghc
+    , ghc-exactprint
+    , ghcide                ^>=1.2
+    , hls-plugin-api        ^>=1.1
+    , lens
+    , lsp
+    , shake
+    , text
+    , transformers
+    , unordered-containers
 
+  default-language:   Haskell2010
+  default-extensions:
+    DataKinds
+    TypeOperators
+
+  ghc-options:        -Wno-unticked-promoted-constructors
+
+test-suite tests
+  type:             exitcode-stdio-1.0
   default-language: Haskell2010
-  default-extensions: DataKinds, TypeOperators
-  ghc-options: -Wno-unticked-promoted-constructors
+  hs-source-dirs:   test
+  main-is:          Main.hs
+  ghc-options:      -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+    , base
+    , bytestring
+    , filepath
+    , hls-class-plugin
+    , hls-test-utils  ^>= 1.0
+    , lens
+    , lsp-test
+    , lsp-types
+    , text
diff --git a/src/Ide/Plugin/Class.hs b/src/Ide/Plugin/Class.hs
--- a/src/Ide/Plugin/Class.hs
+++ b/src/Ide/Plugin/Class.hs
@@ -12,30 +12,32 @@
 import           Class
 import           ConLike
 import           Control.Applicative
-import           Control.Lens hiding (List, use)
+import           Control.Lens                            hiding (List, use)
 import           Control.Monad
 import           Control.Monad.Trans.Class
 import           Control.Monad.Trans.Maybe
 import           Data.Aeson
 import           Data.Char
 import           Data.List
-import qualified Data.Map.Strict as Map
+import qualified Data.Map.Strict                         as Map
 import           Data.Maybe
-import qualified Data.Text as T
-import           Development.IDE hiding (pluginHandlers)
-import           Development.IDE.Core.PositionMapping (fromCurrentRange, toCurrentRange)
-import           Development.IDE.GHC.Compat hiding (getLoc)
+import qualified Data.Text                               as T
+import           Development.IDE                         hiding (pluginHandlers)
+import           Development.IDE.Core.PositionMapping    (fromCurrentRange,
+                                                          toCurrentRange)
+import           Development.IDE.GHC.Compat              hiding (getLoc)
 import           Development.IDE.Spans.AtPoint
-import qualified GHC.Generics as Generics
-import           GhcPlugins hiding (Var, getLoc, (<>))
+import qualified GHC.Generics                            as Generics
+import           GhcPlugins                              hiding (Var, getLoc,
+                                                          (<>))
 import           Ide.PluginUtils
 import           Ide.Types
 import           Language.Haskell.GHC.ExactPrint
 import           Language.Haskell.GHC.ExactPrint.Parsers (parseDecl)
-import           Language.Haskell.GHC.ExactPrint.Types hiding (GhcPs, Parens)
+import           Language.Haskell.GHC.ExactPrint.Types   hiding (GhcPs, Parens)
 import           Language.LSP.Server
 import           Language.LSP.Types
-import qualified Language.LSP.Types.Lens as J
+import qualified Language.LSP.Types.Lens                 as J
 import           SrcLoc
 import           TcEnv
 import           TcRnMonad
@@ -87,7 +89,7 @@
     makeMethodDecl df mName =
       case parseDecl df (T.unpack mName) . T.unpack $ toMethodName mName <> " = _" of
         Right (ann, d) -> Just (setPrecedingLines d 1 indent ann, d)
-        Left _ -> Nothing
+        Left _         -> Nothing
 
     addMethodDecls :: ParsedSource -> [LHsDecl GhcPs] -> Transform (Located (HsModule GhcPs))
     addMethodDecls ps mDecls = do
@@ -161,10 +163,9 @@
 
         mkCmdParams methodGroup = [toJSON (AddMinimalMethodsParams uri range (List methodGroup))]
 
-        mkCodeAction title
+        mkCodeAction title cmd
           = InR
-          . CodeAction title (Just CodeActionQuickFix) (Just (List [])) Nothing Nothing Nothing
-          . Just
+          $ CodeAction title (Just CodeActionQuickFix) (Just (List [])) Nothing Nothing Nothing (Just cmd) Nothing
 
     findClassIdentifier docPath range = do
       (hieAstResult, pmap) <- MaybeT . runAction "classplugin" state $ useWithStale GetHieAst docPath
@@ -203,7 +204,7 @@
 minDefToMethodGroups :: BooleanFormula Name -> [[T.Text]]
 minDefToMethodGroups = go
   where
-    go (Var mn) = [[T.pack . occNameString . occName $ mn]]
-    go (Or ms) = concatMap (go . unLoc) ms
-    go (And ms) = foldr (liftA2 (<>)) [[]] (fmap (go . unLoc) ms)
+    go (Var mn)   = [[T.pack . occNameString . occName $ mn]]
+    go (Or ms)    = concatMap (go . unLoc) ms
+    go (And ms)   = foldr (liftA2 (<>)) [[]] (fmap (go . unLoc) ms)
     go (Parens m) = go (unLoc m)
diff --git a/test/Main.hs b/test/Main.hs
new file mode 100644
--- /dev/null
+++ b/test/Main.hs
@@ -0,0 +1,78 @@
+{-# LANGUAGE LambdaCase          #-}
+{-# LANGUAGE OverloadedStrings   #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeOperators       #-}
+module Main
+  ( main
+  )
+where
+
+import           Control.Lens            hiding ((<.>))
+import qualified Data.ByteString.Lazy    as BS
+import qualified Data.Text.Encoding      as T
+import qualified Ide.Plugin.Class        as Class
+import qualified Language.LSP.Types.Lens as J
+import           System.FilePath
+import           Test.Hls
+
+main :: IO ()
+main = defaultTestRunner tests
+
+plugin :: PluginDescriptor IdeState
+plugin = Class.descriptor "class"
+
+tests :: TestTree
+tests = testGroup
+  "class"
+  [ testCase "Produces addMinimalMethodPlaceholders code actions for one instance" $ do
+      runSessionWithServer plugin classPath $ do
+        doc <- openDoc "T1.hs" "haskell"
+        _ <- waitForDiagnosticsFromSource doc "typecheck"
+        caResults <- getAllCodeActions doc
+        liftIO $ map (^? _CACodeAction . J.title) caResults
+          @?=
+          [ Just "Add placeholders for '=='"
+          , Just "Add placeholders for '/='"
+          ]
+  , glodenTest "Creates a placeholder for '=='" "T1" "eq"
+    $ \(eqAction:_) -> do
+      executeCodeAction eqAction
+  , glodenTest "Creates a placeholder for '/='" "T1" "ne"
+    $ \(_:neAction:_) -> do
+      executeCodeAction neAction
+  , glodenTest "Creates a placeholder for 'fmap'" "T2" "fmap"
+    $ \(_:_:fmapAction:_) -> do
+      executeCodeAction fmapAction
+  , glodenTest "Creates a placeholder for multiple methods 1" "T3" "1"
+    $ \(mmAction:_) -> do
+      executeCodeAction mmAction
+  , glodenTest "Creates a placeholder for multiple methods 2" "T3" "2"
+    $ \(_:mmAction:_) -> do
+      executeCodeAction mmAction
+  , glodenTest "Creates a placeholder for a method starting with '_'" "T4" ""
+    $ \(_fAction:_) -> do
+      executeCodeAction _fAction
+  ]
+
+_CACodeAction :: Prism' (Command |? CodeAction) CodeAction
+_CACodeAction = prism' InR $ \case
+  InR action -> Just action
+  _          -> Nothing
+
+classPath :: FilePath
+classPath = "test" </> "testdata"
+
+glodenTest :: String -> FilePath -> FilePath -> ([CodeAction] -> Session ()) -> TestTree
+glodenTest name fp deco execute
+  = goldenGitDiff name (classPath </> fpWithDeco <.> "expected" <.> "hs")
+    $ runSessionWithServer plugin classPath
+    $ do
+      doc <- openDoc (fp <.> "hs") "haskell"
+      _ <- waitForDiagnosticsFromSource doc "typecheck"
+      actions <- concatMap (^.. _CACodeAction) <$> getAllCodeActions doc
+      execute actions
+      BS.fromStrict . T.encodeUtf8 <$> skipManyTill anyMessage (getDocumentEdit doc)
+  where
+    fpWithDeco
+      | deco == "" = fp
+      | otherwise  = fp <.> deco
diff --git a/test/testdata/T1.eq.expected.hs b/test/testdata/T1.eq.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T1.eq.expected.hs
@@ -0,0 +1,6 @@
+module T1 where
+
+data X = X
+
+instance Eq X where
+  (==) = _
diff --git a/test/testdata/T1.hs b/test/testdata/T1.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T1.hs
@@ -0,0 +1,5 @@
+module T1 where
+
+data X = X
+
+instance Eq X where
diff --git a/test/testdata/T1.ne.expected.hs b/test/testdata/T1.ne.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T1.ne.expected.hs
@@ -0,0 +1,6 @@
+module T1 where
+
+data X = X
+
+instance Eq X where
+  (/=) = _
diff --git a/test/testdata/T2.fmap.expected.hs b/test/testdata/T2.fmap.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T2.fmap.expected.hs
@@ -0,0 +1,13 @@
+module T2 where
+
+data X a
+  = A a
+  | B
+
+instance
+  (Eq a) => Eq (X a)
+ where
+
+instance
+  Functor X where
+  fmap = _
diff --git a/test/testdata/T2.hs b/test/testdata/T2.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T2.hs
@@ -0,0 +1,12 @@
+module T2 where
+
+data X a
+  = A a
+  | B
+
+instance
+  (Eq a) => Eq (X a)
+ where
+
+instance
+  Functor X
diff --git a/test/testdata/T3.1.expected.hs b/test/testdata/T3.1.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T3.1.expected.hs
@@ -0,0 +1,13 @@
+module T3 where
+
+class Test a where
+  f :: a
+  f = h
+  g :: a
+  h :: a
+  h = f
+  {-# MINIMAL f, g | g, h #-}
+
+instance Test [a] where
+  f = _
+  g = _
diff --git a/test/testdata/T3.2.expected.hs b/test/testdata/T3.2.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T3.2.expected.hs
@@ -0,0 +1,13 @@
+module T3 where
+
+class Test a where
+  f :: a
+  f = h
+  g :: a
+  h :: a
+  h = f
+  {-# MINIMAL f, g | g, h #-}
+
+instance Test [a] where
+  g = _
+  h = _
diff --git a/test/testdata/T3.hs b/test/testdata/T3.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T3.hs
@@ -0,0 +1,11 @@
+module T3 where
+
+class Test a where
+  f :: a
+  f = h
+  g :: a
+  h :: a
+  h = f
+  {-# MINIMAL f, g | g, h #-}
+
+instance Test [a] where
diff --git a/test/testdata/T4.expected.hs b/test/testdata/T4.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T4.expected.hs
@@ -0,0 +1,8 @@
+module T4 where
+
+class Test a where
+  _f :: a
+  {-# MINIMAL _f #-}
+
+instance Test Int where
+  _f = _
diff --git a/test/testdata/T4.hs b/test/testdata/T4.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/T4.hs
@@ -0,0 +1,7 @@
+module T4 where
+
+class Test a where
+  _f :: a
+  {-# MINIMAL _f #-}
+
+instance Test Int where