silenceStdErr to honor LSP_TEST_LOG_STDERR

Author: pepeiborra

hls-test-utils/src/Test/Hls.hs

@@ -59,6 +59,7 @@ import           Language.LSP.Types                hiding
 import           Language.LSP.Types.Capabilities   (ClientCapabilities)
 import           System.Directory                  (getCurrentDirectory,
                                                     setCurrentDirectory)
+import           System.Environment.Blank          (getEnvDefault)
 import           System.FilePath
 import           System.IO.Extra
 import           System.IO.Unsafe                  (unsafePerformIO)
@@ -133,15 +134,19 @@ runSessionWithServerFormatter plugin formatter =
 
 -- | Run an action, with stderr silenced
 silenceStderr :: IO a -> IO a
-silenceStderr action = withTempFile $ \temp ->
-  bracket (openFile temp ReadWriteMode) hClose $ \h -> do
-    old <- hDuplicate stderr
-    buf <- hGetBuffering stderr
-    h `hDuplicateTo'` stderr
-    action `finally` do
-      old `hDuplicateTo'` stderr
-      hSetBuffering stderr buf
-      hClose old
+silenceStderr action = do
+  showStderr <- getEnvDefault "LSP_TEST_LOG_STDERR" "0"
+  case showStderr of
+    "0" -> withTempFile $ \temp ->
+      bracket (openFile temp ReadWriteMode) hClose $ \h -> do
+        old <- hDuplicate stderr
+        buf <- hGetBuffering stderr
+        h `hDuplicateTo'` stderr
+        action `finally` do
+          old `hDuplicateTo'` stderr
+          hSetBuffering stderr buf
+          hClose old
+    _ -> action
 
 -- | Restore cwd after running an action
 keepCurrentDirectory :: IO a -> IO a