More test cases

They should be sufficient to pin down the behavior.

Author: odersky

tests/run/contrarivant.scala

@@ -1,17 +1,26 @@
 object Test extends App {
 
+  // toplevel contra
   implicit def f: String => String = x => "f"
-
   implicit def g: Object => String = x => "g"
-
   def h(implicit x: String => String) = x("")
+  assert(h == "f", h)
 
+  // nested contra
   implicit def fs: List[String => String] = List(f)
-
   implicit def gs: List[Object => String] = List(g)
-
   def hs(implicit xs: List[String => String]) = xs.head("")
+  assert(hs == "f", hs)
+
+  // covariant subapplication nested in toplevel contra
+  implicit def f2: (Unit => String) => String = x => "f2"
+  implicit def g2: (Unit => Object) => String = x => "g2"
+  def h2(implicit x: (Unit => String) => String) = x(_ => "")
+  assert(h2 == "f2", h2)
 
-  assert(h == "f")
-  assert(hs == "f")
+  // covariant subapplication nested in nested contra
+  implicit def fs2: List[(Unit => String) => String] = List(f2)
+  implicit def gs2: List[(Unit => Object) => String] = List(g2)
+  def hs2(implicit xs: List[(Unit => String) => String]) = xs.head(_ => "")
+  assert(hs2 == "f2", hs2)
 }