Parallelize the test suite (for real this time) (#374)

This is a better attempt at fixing #123 in which I use `tasty-1.2`'s
new API for expressing test dependencies. (I previously attempted to
parallelize the test suite in commit
7962d08, but that ended
disastrously. See
#123 (comment)
for more details.)

I also use `-maxN16` this time instead of `-N`. It's unclear how well
this scales, so I decided to be cautious at cap it off at 16. Testing
this locally on my machine, using `-maxN16` reduces the build time
from about 90 to 15 seconds, which is pretty nice in its own right.
(If more adventurous users want to attempt using more threads, they
can always override this themselves.)

.travis.yml

@@ -84,6 +84,7 @@ install:
   - "echo '  type: git' >> cabal.project"
   - "echo '  location: https://github.com/goldfirere/th-desugar' >> cabal.project"
   - "echo '  tag: 567145eddeb5f6692a75e74d4a2dc575b1ad6f29' >> cabal.project"
+  - "printf 'write-ghc-environment-files: always' >> cabal.project"
   - touch cabal.project.local
   - "if ! $NOINSTALLEDCONSTRAINTS; then for pkg in $($HCPKG list --simple-output); do echo $pkg  | grep -vw -- singletons | grep -vw -- accept-all | sed 's/^/constraints: /' | sed 's/-[^-]*$/ installed/' >> cabal.project.local; done; fi"
   - cat cabal.project || true
@@ -112,6 +113,7 @@ script:
   - "echo '  type: git' >> cabal.project"
   - "echo '  location: https://github.com/goldfirere/th-desugar' >> cabal.project"
   - "echo '  tag: 567145eddeb5f6692a75e74d4a2dc575b1ad6f29' >> cabal.project"
+  - "printf 'write-ghc-environment-files: always' >> cabal.project"
   - touch cabal.project.local
   - "if ! $NOINSTALLEDCONSTRAINTS; then for pkg in $($HCPKG list --simple-output); do echo $pkg  | grep -vw -- singletons | grep -vw -- accept-all | sed 's/^/constraints: /' | sed 's/-[^-]*$/ installed/' >> cabal.project.local; done; fi"
   - cat cabal.project || true

singletons.cabal

@@ -144,7 +144,7 @@ library
 test-suite singletons-test-suite
   type:               exitcode-stdio-1.0
   hs-source-dirs:     tests
-  ghc-options:        -Wall
+  ghc-options:        -Wall -threaded -with-rtsopts=-maxN16
   default-language:   Haskell2010
   main-is:            SingletonsTestSuite.hs
   other-modules:      ByHand
@@ -155,5 +155,5 @@ test-suite singletons-test-suite
                       filepath >= 1.3,
                       process >= 1.1,
                       singletons,
-                      tasty >= 0.6,
+                      tasty >= 1.2,
                       tasty-golden >= 2.2

tests/SingletonsTestSuite.hs

@@ -2,16 +2,13 @@ module Main (
     main
  ) where
 
-import Test.Tasty               ( TestTree, defaultMain, testGroup          )
+import Test.Tasty               ( DependencyType(..), TestTree
+                                , after, defaultMain, testGroup )
 import SingletonsTestSuiteUtils ( compileAndDumpStdTest, compileAndDumpTest
-                                , testCompileAndDumpGroup, ghcOpts
-                             --   , cleanFiles
-                                )
+                                , testCompileAndDumpGroup, ghcOpts )
 
 main :: IO ()
-main = do
---  cleanFiles    We really need to parallelize the testsuite.
-  defaultMain tests
+main = defaultMain tests
 
 tests :: TestTree
 tests =
@@ -21,29 +18,44 @@ tests =
     , compileAndDumpStdTest "Empty"
     , compileAndDumpStdTest "Maybe"
     , compileAndDumpStdTest "BoxUnBox"
-    , compileAndDumpStdTest "Operators"
-    , compileAndDumpStdTest "HigherOrder"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "Operators"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "HigherOrder"
     , compileAndDumpStdTest "Contains"
-    , compileAndDumpStdTest "AsPattern"
-    , compileAndDumpStdTest "DataValues"
-    , compileAndDumpStdTest "EqInstances"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "AsPattern"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "DataValues"
+    , after AllSucceed "$3 == \"Empty\"" .
+      after AllSucceed "$3 == \"Operators\"" .
+      compileAndDumpStdTest "EqInstances"
     , compileAndDumpStdTest "CaseExpressions"
-    , compileAndDumpStdTest "Star"
-    , compileAndDumpStdTest "ReturnFunc"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "Star"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "ReturnFunc"
     , compileAndDumpStdTest "Lambdas"
-    , compileAndDumpStdTest "LambdasComprehensive"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "LambdasComprehensive"
     , compileAndDumpStdTest "Error"
     , compileAndDumpStdTest "TopLevelPatterns"
-    , compileAndDumpStdTest "LetStatements"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "LetStatements"
     , compileAndDumpStdTest "LambdaCase"
-    , compileAndDumpStdTest "Sections"
-    , compileAndDumpStdTest "PatternMatching"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "Sections"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "PatternMatching"
     , compileAndDumpStdTest "Records"
     , compileAndDumpStdTest "T29"
     , compileAndDumpStdTest "T33"
     , compileAndDumpStdTest "T54"
-    , compileAndDumpStdTest "Classes"
-    , compileAndDumpStdTest "Classes2"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "Classes"
+    , afterSingletonsNat .
+      after AllSucceed "$3 == \"Classes\"" .
+      compileAndDumpStdTest "Classes2"
     , compileAndDumpStdTest "FunDeps"
     , compileAndDumpStdTest "T78"
     , compileAndDumpStdTest "OrdDeriving"
@@ -107,17 +119,22 @@ tests =
     testCompileAndDumpGroup "Promote"
     [ compileAndDumpStdTest "Constructors"
     , compileAndDumpStdTest "GenDefunSymbols"
-    , compileAndDumpStdTest "Newtypes"
+    , afterSingletonsNat .
+      compileAndDumpStdTest "Newtypes"
     , compileAndDumpStdTest "Pragmas"
     , compileAndDumpStdTest "Prelude"
     , compileAndDumpStdTest "T180"
     , compileAndDumpStdTest "T361"
     ],
     testGroup "Database client"
     [ compileAndDumpTest "GradingClient/Database" ghcOpts
-    , compileAndDumpTest "GradingClient/Main"     ghcOpts
+    , after AllSucceed "$3 == \"Database\"" $
+      compileAndDumpTest "GradingClient/Main"     ghcOpts
     ],
     testCompileAndDumpGroup "InsertionSort"
     [ compileAndDumpStdTest "InsertionSortImp"
     ]
   ]
+
+afterSingletonsNat :: TestTree -> TestTree
+afterSingletonsNat = after AllSucceed "$3 == \"Nat\""