[oss] TestRunner: nicer failure diagnostics

Before:

```
FAIL
    Exception: HUnitFailure (Just (SrcLoc {srcLocPackage = "glean-0.1.0.0-inplace-regression-test-lib", srcLocModule = "Glean.Regression.Snapshot.Result", srcLocFile = "glean/test/regression/Glean/Regression/Snapshot/Result.hs", srcLocStartLine = 34, srcLocStartCol = 25, srcLocEndLine = 34, srcLocEndCol = 44})) (Reason "filerange.out: unexpected result\n19,29d18\n<         \"columnBegin\": 1,\n<         \"lineEnd\": 53,\n<         \"columnEnd\": 1\n<       }\n<     }\n<   },\n<   {\n<     \"key\": {\n<       \"file\": { \"key\": \"example.ts\" },\n<       \"range\": {\n<         \"lineBegin\": 9,\n74,84d62\n<         \"columnBegin\": 1,\n<         \"lineEnd\": 42,\n<         \"columnEnd\": 3\n<       }\n<     }\n<   },\n<   {\n<     \"key\": {\n<       \"file\": { \"key\": \"example.ts\" },\n<       \"range\": {\n<         \"lineBegin\": 14,\n107,117d84\n<         \"columnBegin\": 3,\n<         \"lineEnd\": 33,\n<         \"columnEnd\": 3\n<       }\n<     }\n<   },\n<   {\n<     \"key\": {\n<       \"file\": { \"key\": \"example.ts\" },\n<       \"range\": {\n<         \"lineBegin\": 15,\n382,392d348\n<         \"columnBegin\": 3,\n<         \"lineEnd\": 41,\n<         \"columnEnd\": 5\n<       }\n<     }\n<   },\n<   {\n<     \"key\": {\n<       \"file\": { \"key\": \"example.ts\" },\n<       \"range\": {\n<         \"lineBegin\": 34,\n528,538d483\n<       }\n<     }\n<   },\n<   {\n<     \"key\": {\n<       \"file\": { \"key\": \"example.ts\" },\n<       \"range\": {\n<         \"lineBegin\": 46,\n<         \"columnBegin\": 1,\n<         \"lineEnd\": 52,\n<         \"columnEnd\": 1\n\nfilerange.perf: unexpected result\n3c3\n<   \"facts_searched\": { \"scip.FileRange.1\": 62 },\n---\n>   \"facts_searched\": { \"scip.FileRange.1\": 57 },\n\n")
```

After:

```
FAIL (4.24s)
    glean/test/regression/Glean/Regression/Snapshot/Result.hs:34:
    filerange.out: unexpected result
    19,29d18
    <         "columnBegin": 1,
    <         "lineEnd": 53,
    <         "columnEnd": 1
    <       }
    <     }
    <   },
    <   {
    <     "key": {
    <       "file": { "key": "example.ts" },
    <       "range": {
    <         "lineBegin": 9,
    74,84d62
    <         "columnBegin": 1,
    <         "lineEnd": 42,
    <         "columnEnd": 3
    <       }
    <     }
    <   },
    <   {
    <     "key": {
    <       "file": { "key": "example.ts" },
    <       "range": {
    <         "lineBegin": 14,
    107,117d84
    <         "columnBegin": 3,
    <         "lineEnd": 33,
    <         "columnEnd": 3
    <       }
    <     }
    <   },
    <   {
    <     "key": {
    <       "file": { "key": "example.ts" },
    <       "range": {
    <         "lineBegin": 15,
    382,392d348
    <         "columnBegin": 3,
    <         "lineEnd": 41,
    <         "columnEnd": 5
    <       }
    <     }
    <   },
    <   {
    <     "key": {
    <       "file": { "key": "example.ts" },
    <       "range": {
    <         "lineBegin": 34,
    528,538d483
    <       }
    <     }
    <   },
    <   {
    <     "key": {
    <       "file": { "key": "example.ts" },
    <       "range": {
    <         "lineBegin": 46,
    <         "columnBegin": 1,
    <         "lineEnd": 52,
    <         "columnEnd": 1

    filerange.perf: unexpected result
    3c3
    <   "facts_searched": { "scip.FileRange.1": 62 },
    ---
    >   "facts_searched": { "scip.FileRange.1": 57 },
```

Author: simonmar

glean.cabal.in

@@ -228,7 +228,7 @@ library stubs
         mangle,
         template-haskell,
         tasty,
-        tasty-hunit-adapter
+        tasty-hunit
 
 library logger
     import: fb-haskell, fb-cpp, deps

glean/github/TestRunner.hs

@@ -8,18 +8,21 @@
 
 module TestRunner (module TestRunner) where
 
+import Control.Exception
 import System.Environment (withArgs)
 import Test.HUnit
 import qualified Test.Tasty as Tasty
-import qualified Test.Tasty.HUnit.Adapter as Tasty
+import qualified Test.HUnit.Base  as HUB
+import qualified Test.Tasty.HUnit as TFH
+import Test.HUnit.Lang as HUnitInternals (HUnitFailure(..), formatFailureReason)
 
 -- | Wraps the HUnit test using tasty, so we get parallel test runs,
 -- test listing, and test selection.
 testRunner :: Test -> IO ()
 testRunner t =
   Tasty.defaultMain $
   Tasty.testGroup "test" $
-  Tasty.hUnitTestToTestTree t
+  hUnitTestToTestTree t
 
 data TestAction = TestAction
 
@@ -40,4 +43,28 @@ testRunnerAction _ t =
   withArgs [] $
   Tasty.defaultMain $
   Tasty.testGroup "test" $
-  Tasty.hUnitTestToTestTree t
+  hUnitTestToTestTree t
+
+-- | Convert existing HUnit test to a TestTree list that can be used
+-- with tasty.  This is modified from the tasty-hunit-adapter package,
+-- adding conversion of the original HUnitFailure exception into
+-- Tasty's version, so that we get better diagnostics.
+hUnitTestToTestTree :: HUB.Test -> [Tasty.TestTree]
+hUnitTestToTestTree = go ""
+  where
+    go desc (HUB.TestCase a)    = [TFH.testCase desc (rethrow a)]
+    go desc (HUB.TestLabel s t)
+      | null desc = go s t
+      | otherwise = go (desc ++ ":" ++ s) t
+    go desc (HUB.TestList ts)
+        -- If the list occurs at the top level (with no description above it),
+        -- just return that list straightforwardly
+      | null desc = concatMap (go "") ts
+        -- If the list occurs with a description, turn that into a honest-to-god
+        -- test group. This is heuristic, but likely to give good results
+      | otherwise = [Tasty.testGroup desc (concatMap (go "") ts)]
+
+    rethrow t = --recomp
+      t `catch` \(HUnitInternals.HUnitFailure loc reason) ->
+        throwIO $
+          TFH.HUnitFailure loc (HUnitInternals.formatFailureReason reason)