another test for issue Neil talked about

Author: MaximilianAlgehed

examples/Constrained/Examples/Map.hs

@@ -125,3 +125,16 @@ mapSetSmall = constrained $ \x ->
 mapIsJust :: Specification (Int, Int)
 mapIsJust = constrained' $ \ [var| x |] [var| y |] ->
   just_ x ==. lookup_ y (lit $ Map.fromList [(z, z) | z <- [100 .. 102]])
+
+eitherKeys :: Specification ([Int], [Int], Map (Either Int Int) Int)
+eitherKeys = constrained' $ \ [var| as |] [var| bs |] [var| m |] ->
+  [
+    forAll' m $ \ [var| k |] _v ->
+      [ caseOn k
+          (branch $ \ a -> a `elem_` as)
+          (branch $ \ b -> b `elem_` bs)
+      , reify as (map Left) $ \ ls ->
+        reify bs (map Right) $ \ rs ->
+          k `elem_` ls ++. rs
+      ]
+  ]

test/Constrained/Tests.hs

@@ -85,6 +85,7 @@ tests nightly =
     testSpec "mapElemKeySpec" mapElemKeySpec
     -- TODO: double shrinking
     testSpecNoShrink "mapIsJust" mapIsJust
+    testSpecNoShrink "eitherKeys" eitherKeys
     testSpecNoShrink "intSpec" intSpec
     testSpecNoShrink "mapPairSpec" mapPairSpec
     testSpecNoShrink "mapEmptyDomainSpec" mapEmptyDomainSpec