Reorder tests and add executable test

Reorder the test to endsure some liquid products are available
in /test/testdata/liquid/.liquid at first run.
Also add a test to see if the liquid haskell excutable is available.

Author: meck

test/unit/LiquidSpec.hs

@@ -8,6 +8,7 @@ import           Data.List
 import qualified Data.Text            as T
 import qualified Data.Text.IO         as T
 import           Data.Monoid ((<>))
+import           Data.Maybe (isJust)
 import           Haskell.Ide.Engine.MonadTypes
 import           Haskell.Ide.Engine.Plugin.Liquid
 import           System.Directory
@@ -24,7 +25,20 @@ spec = do
     cwd <- runIO getCurrentDirectory
 
     -- ---------------------------------
+    it "finds liquid haskell exe in $PATH" $ findExecutable "liquid" >>= (`shouldSatisfy` isJust)
 
+    -- ---------------------------------
+    -- This produces some products in /test/testdata/liquid/.liquid/ that is used in subsequent test
+    it "runs the liquid haskell exe" $ do
+      let
+        fp = cwd </> "test/testdata/liquid/Evens.hs"
+        -- fp = "/home/alanz/tmp/haskell-proc-play/Evens.hs"
+        -- uri = filePathToUri fp
+      Just (ef, (msg:_)) <- runLiquidHaskell fp
+      msg `shouldSatisfy` isPrefixOf "RESULT\n[{\"start\":{\"line\":9,\"column\":1},\"stop\":{\"line\":9,\"column\":8},\"message\":\"Error: Liquid Type Mismatch\\n  Inferred type\\n    VV : {v : Int | v == (7 : int)}\\n \\n  not a subtype of Required type\\n    VV : {VV : Int | VV mod 2 == 0}\\n"
+      ef `shouldBe` ExitFailure 1
+
+    -- ---------------------------------
     it "gets annot file paths" $ do
       let
         uri = filePathToUri $ cwd </> "test/testdata/liquid/Evens.hs"
@@ -107,14 +121,3 @@ spec = do
       n `shouldBe` Nothing
 
     -- ---------------------------------
-
-    it "runs the liquid haskell exe" $ do
-      let
-        fp = cwd </> "test/testdata/liquid/Evens.hs"
-        -- fp = "/home/alanz/tmp/haskell-proc-play/Evens.hs"
-        -- uri = filePathToUri fp
-      Just (ef, (msg:_)) <- runLiquidHaskell fp
-      msg `shouldSatisfy` isPrefixOf "RESULT\n[{\"start\":{\"line\":9,\"column\":1},\"stop\":{\"line\":9,\"column\":8},\"message\":\"Error: Liquid Type Mismatch\\n  Inferred type\\n    VV : {v : Int | v == (7 : int)}\\n \\n  not a subtype of Required type\\n    VV : {VV : Int | VV mod 2 == 0}\\n"
-      ef `shouldBe` ExitFailure 1
-
-    -- ---------------------------------