Fix flaky test

Author: pepeiborra

ghcide/test/exe/Main.hs

@@ -421,16 +421,16 @@ diagnosticTests = testGroup "diagnostics"
       let contentA = T.unlines [ "module ModuleA where" ]
       _ <- createDoc "ModuleA.hs" "haskell" contentA
       expectDiagnostics [("ModuleB.hs", [])]
-  , ignoreTestBecause "Flaky #2831" $ testSessionWait "add missing module (non workspace)" $ do
+  , testSession' "add missing module (non workspace)" $ \tmpDir -> do
       -- need to canonicalize in Mac Os
-      tmpDir <- liftIO $ canonicalizePath =<< getTemporaryDirectory
       let contentB = T.unlines
             [ "module ModuleB where"
             , "import ModuleA ()"
             ]
       _ <- createDoc (tmpDir </> "ModuleB.hs") "haskell" contentB
       expectDiagnostics [(tmpDir </> "ModuleB.hs", [(DsError, (1, 7), "Could not find module")])]
       let contentA = T.unlines [ "module ModuleA where" ]
+      liftIO $ writeFile (tmpDir </> "ModuleA.hs") $ T.unpack contentA
       _ <- createDoc (tmpDir </> "ModuleA.hs") "haskell" contentA
       expectDiagnostics [(tmpDir </> "ModuleB.hs", [])]
   , testSessionWait "cyclic module dependency" $ do