ability to run code and check output in tests

tests/Equality.newt

@@ -0,0 +1,24 @@
+module Equality
+
+data Eq : {A : U} -> A -> A -> U where
+  Refl : {A : U} {a : A} -> Eq a a
+
+-- Some magic is not happening here.
+
+sym : {A : U} {x y : A} -> Eq x y -> Eq y x
+sym Refl = Refl
+
+trans : {A : U} {x y z : A} -> Eq x y -> Eq y z -> Eq x z
+trans Refl Refl = Refl
+
+coerce : {A B : U} -> Eq A B -> A -> B
+coerce Refl a = a
+
+J : {A : U} ->
+    {C : (x y : A) -> Eq x y -> U} ->
+    (c : (x : _) -> C x x Refl) ->
+    (x y : A) ->
+    (p : Eq x y) ->
+    C x y p
+-- this was failing until I constrained scrutinee to the constructor + args
+J c x y Refl = c x