tests: use "keepalive" tmux session and unique session names

We have experienced problems with the `tmux new-session` command:
a race of server availability when the server is being torn down
after the previous session gets killed.  Create a "keepalive"
session whose lifetime is the whole of the acceptance tests, to
prevent the server from being killed.

Also sequentially number the test sessions to avoid any potential
races when sessions are being killed and started.

Fixes: #123

test/TestUserAcceptance.hs

@@ -8,6 +8,7 @@ module TestUserAcceptance where
 
 import qualified Data.Text as T
 import System.IO.Temp (createTempDirectory, getCanonicalTemporaryDirectory)
+import Data.Functor (($>))
 import Data.Ini (parseIni, writeIniFileWith, KeySeparator(..), WriteIniSettings(..))
 import Data.Semigroup ((<>))
 import Control.Concurrent (threadDelay)
@@ -19,7 +20,7 @@ import Data.Maybe (isJust)
 import Control.Monad.IO.Class (liftIO)
 import Control.Monad.Reader (runReaderT, ask, ReaderT)
 
-import Control.Lens (view, _3, _2)
+import Control.Lens (Lens', view)
 import Data.List (isInfixOf, intercalate)
 import System.Process (callProcess, readProcess)
 import System.Directory
@@ -37,20 +38,24 @@ data Condition
 systemTests ::
   TestTree
 systemTests =
-    testGroup
-        "user acceptance tests"
-        [ testUserViewsMailSuccessfully
-        , testUserCanManipulateNMQuery
-        , testUserCanSwitchBackToIndex
-        , testCanToggleHeaders
-        , testSetsMailToRead
-        , testErrorHandling
-        , testHelp
-        , testManageTagsOnMails
-        , testManageTagsOnThreads
-        ]
-
-testManageTagsOnMails :: TestTree
+  withResource pre post $ \_ ->
+    testGroup "user acceptance tests" $ zipWith ($) tests [0..]
+  where
+    pre = let n = "keepalive" in setUpTmuxSession n $> n
+    post = cleanUpTmuxSession
+    tests =
+      [ testUserViewsMailSuccessfully
+      , testUserCanManipulateNMQuery
+      , testUserCanSwitchBackToIndex
+      , testCanToggleHeaders
+      , testSetsMailToRead
+      , testErrorHandling
+      , testHelp
+      , testManageTagsOnMails
+      , testManageTagsOnThreads
+      ]
+
+testManageTagsOnMails :: Int -> TestTree
 testManageTagsOnMails = withTmuxSession "manage tags on mails" $
   \step -> do
     startApplication
@@ -95,7 +100,7 @@ testManageTagsOnMails = withTmuxSession "manage tags on mails" $
 
     pure ()
 
-testManageTagsOnThreads :: TestTree
+testManageTagsOnThreads :: Int -> TestTree
 testManageTagsOnThreads = withTmuxSession "manage tags on threads" $
   \step -> do
     startApplication
@@ -117,7 +122,7 @@ testManageTagsOnThreads = withTmuxSession "manage tags on threads" $
 
     pure ()
 
-testHelp :: TestTree
+testHelp :: Int -> TestTree
 testHelp = withTmuxSession "help view" $
   \step -> do
     startApplication
@@ -128,8 +133,7 @@ testHelp = withTmuxSession "help view" $
     sendKeys "Escape" (Literal "Purebred")
     pure ()
 
-testErrorHandling ::
-  TestTree
+testErrorHandling :: Int -> TestTree
 testErrorHandling = withTmuxSession "error handling" $
   \step -> do
     startApplication
@@ -149,8 +153,7 @@ testErrorHandling = withTmuxSession "error handling" $
 
     pure ()
 
-testSetsMailToRead ::
-  TestTree
+testSetsMailToRead :: Int -> TestTree
 testSetsMailToRead = withTmuxSession "user can toggle read tag" $
   \step -> do
     startApplication
@@ -166,8 +169,7 @@ testSetsMailToRead = withTmuxSession "user can toggle read tag" $
     sendKeys "t" (Regex (buildAnsiRegex ["1"] ["37"] ["43"] <> ".*Testmail"))
     pure ()
 
-testCanToggleHeaders ::
-  TestTree
+testCanToggleHeaders :: Int -> TestTree
 testCanToggleHeaders = withTmuxSession "user can toggle Headers" $
   \step -> do
     startApplication
@@ -184,8 +186,7 @@ testCanToggleHeaders = withTmuxSession "user can toggle Headers" $
     out <- sendKeys "h" (Literal "This is a test mail")
     assertRegex "Purebred.*\n.*[Ff]rom" out
 
-testUserViewsMailSuccessfully ::
-  TestTree
+testUserViewsMailSuccessfully :: Int -> TestTree
 testUserViewsMailSuccessfully = withTmuxSession "user can view mail" $
   \step -> do
     startApplication
@@ -200,8 +201,7 @@ testUserViewsMailSuccessfully = withTmuxSession "user can view mail" $
     sendKeys "Enter" (Literal "This is a test mail")
     pure ()
 
-testUserCanManipulateNMQuery ::
-  TestTree
+testUserCanManipulateNMQuery :: Int -> TestTree
 testUserCanManipulateNMQuery =
     withTmuxSession
         "manipulating notmuch search query results in empty index" $
@@ -234,8 +234,7 @@ testUserCanManipulateNMQuery =
           sendKeys "Enter" (Literal "HOLY PUREBRED")
           pure ()
 
-testUserCanSwitchBackToIndex ::
-  TestTree
+testUserCanSwitchBackToIndex :: Int -> TestTree
 testUserCanSwitchBackToIndex =
   withTmuxSession "user can switch back to mail index during composition" $
         \step -> do
@@ -268,8 +267,6 @@ testUserCanSwitchBackToIndex =
             sendKeys "Tab" (Literal "test subject")
             pure ()
 
-type Env = (String, String, String)
-
 assertSubstrInOutput :: String -> String -> ReaderT Env IO ()
 assertSubstrInOutput substr out = liftIO $ assertBool (substr <> " not found in\n\n" <> out) $ substr `isInfixOf` out
 
@@ -282,16 +279,35 @@ assertRegex regex out = liftIO $ assertBool
 defaultSessionName :: String
 defaultSessionName = "purebredtest"
 
-tearDown :: (String, String, String) -> IO ()
-tearDown (testdir, _, _)= do
+data Env = Env
+  { _envDir :: FilePath
+  , _envMaildir :: FilePath
+  , _envSessionName :: String
+  }
+
+envDir :: Lens' Env FilePath
+envDir f (Env a b c) = fmap (\a' -> Env a' b c) (f a)
+
+envMaildir :: Lens' Env FilePath
+envMaildir f (Env a b c) = fmap (\b' -> Env a b' c) (f b)
+
+envSessionName :: Lens' Env String
+envSessionName f (Env a b c) = fmap (\c' -> Env a b c') (f c)
+{-# ANN envSessionName ("HLint: ignore Avoid lambda" :: String) #-}
+
+-- | Tear down a test session
+tearDown :: Env -> IO ()
+tearDown (Env testdir _ sessionName) = do
   removeDirectoryRecursive testdir
-  cleanUpTmuxSession defaultSessionName
+  cleanUpTmuxSession sessionName
 
-setUp :: IO (String, String, String)
-setUp = do
-  let sessionname = defaultSessionName
-  (testdir, testmdir) <- setUpTmuxSession sessionname >> setUpTempMaildir
-  pure (testdir, testmdir, sessionname)
+-- | Set up a test session.
+setUp :: Int -> IO Env
+setUp i = do
+  let sessionName = defaultSessionName <> show i
+  setUpTmuxSession sessionName
+  (testdir, maildir) <- setUpTempMaildir
+  pure $ Env testdir maildir sessionName
 
 setUpTempMaildir :: IO (String, String)
 setUpTempMaildir = do
@@ -358,22 +374,28 @@ cleanUpTmuxSession sessionname =
 
 
 -- | Run all application steps in a session defined by session name.
-withTmuxSession :: TestName -> ((String -> IO ()) -> ReaderT Env IO ()) -> TestTree
-withTmuxSession tcname testfx =
-    withResource setUp tearDown $
+withTmuxSession
+  :: TestName
+  -> ((String -> IO ()) -> ReaderT Env IO ())
+  -> Int  -- ^ session sequence number (will be appended to session name)
+  -> TestTree
+withTmuxSession tcname testfx i =
+  withResource (setUp i) tearDown $
       \env -> testCaseSteps tcname $ \stepfx -> env >>= runReaderT (testfx stepfx)
 
 -- | Send keys into the program and wait for the condition to be
 -- met, failing the test if the condition is not met after some
 -- time.
 sendKeys :: String -> Condition -> ReaderT Env IO String
 sendKeys keys expect = do
-    liftIO $ callProcess "tmux" $ communicateSessionArgs keys False
+    sessionName <- getSessionName
+    liftIO $ callProcess "tmux" $ communicateSessionArgs sessionName keys False
     waitForCondition expect defaultCountdown
 
 sendLiteralKeys :: String -> ReaderT Env IO String
 sendLiteralKeys keys = do
-    liftIO $ callProcess "tmux" $ communicateSessionArgs keys True
+    sessionName <- getSessionName
+    liftIO $ callProcess "tmux" $ communicateSessionArgs sessionName keys True
     waitForString keys defaultCountdown
 
 capture :: ReaderT Env IO String
@@ -382,10 +404,10 @@ capture = do
   liftIO $ readProcess "tmux" ["capture-pane", "-e", "-p", "-t", sessionname] []
 
 getSessionName :: ReaderT Env IO String
-getSessionName = view (_3 . ask)
+getSessionName = view (envSessionName . ask)
 
-getTestMaildir :: ReaderT Env IO String
-getTestMaildir = view (_2 . ask)
+getTestMaildir :: ReaderT Env IO FilePath
+getTestMaildir = view (envMaildir . ask)
 
 holdOffTime :: Int
 holdOffTime = 10^6
@@ -436,12 +458,18 @@ defaultCountdown = 5
 startApplication :: ReaderT Env IO ()
 startApplication = do
   testmdir <- getTestMaildir
-  liftIO $ callProcess "tmux" $ communicateSessionArgs ("purebred --database " <> testmdir <> "\r") False
+  sessionName <- getSessionName
+  liftIO $ callProcess "tmux" $
+    communicateSessionArgs sessionName ("purebred --database " <> testmdir <> "\r") False
   void $ waitForString "Purebred: Item" defaultCountdown
 
-communicateSessionArgs :: String -> Bool -> [String]
-communicateSessionArgs keys asLiteral =
-  ["send-keys", "-t", defaultSessionName] <> ["-l" | asLiteral] <> [keys]
+communicateSessionArgs
+  :: String -- ^ session name
+  -> String -- ^ keys
+  -> Bool   -- ^ send the keys literally
+  -> [String]
+communicateSessionArgs sessionName keys asLiteral =
+  ["send-keys", "-t", sessionName] <> ["-l" | asLiteral] <> [keys]
 
 
 type AnsiAttrParam = String