tests/functional2/lang: Migrate eval-okay-patterns

Change-Id: I46e155ed2cc1ffcb75935fc1744c7938af22c0c6

tests/functional2/lang/function-args/eval-okay-formals.out.exp

@@ -0,0 +1 @@
+"abcxyzDDDDEFijk"

tests/functional2/lang/function-args/in-formals.nix

@@ -0,0 +1,16 @@
+let
+
+  f = args@{x, y, z}: x + args.y + z;
+
+  g = {x, y, z}@args: f args;
+
+  h = {x ? "d", y ? x, z ? args.x}@args: x + y + z;
+
+  j = {x, y, z, ...}: x + y + z;
+
+in
+  f {x = "a"; y = "b"; z = "c";} +
+  g {x = "x"; y = "y"; z = "z";} +
+  h {x = "D";} +
+  h {x = "D"; y = "E"; z = "F";} +
+  j {x = "i"; y = "j"; z = "k"; bla = "bla"; foo = "bar";}