Test for precompiled closures

In support of MoarMV/MoarVM#1209

Related to rakudo/rakudo#2897 and a number of other tickets.

Author: vrurg

S10-packages/precompilation.t

@@ -3,7 +3,9 @@ use Test;
 use lib $?FILE.IO.parent(2).add("packages/Test-Helpers");
 use Test::Util;
 
-plan 51;
+my $pkg-path = $?FILE.IO.parent(2).add("packages/S10-packages/lib");
+
+plan 52;
 
 my @*MODULES; # needed for calling CompUnit::Repository::need directly
 
@@ -309,3 +311,10 @@ with make-temp-dir() -> $dir {
 	     'is DEPRECATED does work on Routines in precomped modules';
     }
 }
+
+# GH rakudo/rakudo#2897
+{
+    is_run q<use lib '> ~ $pkg-path ~ q<'; use GH2897-B; (^3).map( { my-counter } ).join(",").print>,
+            { :err(''), :out('0,1,2'), :status => 0 },
+            'closure is preserved after deserialzation';
+}

packages/S10-packages/lib/GH2897-A.pm6

@@ -0,0 +1,7 @@
+use v6;
+unit module GH2897-A;
+
+sub gen-counter is export {
+    my $foo = 0;
+    sub counter { $foo++ }
+}

packages/S10-packages/lib/GH2897-B.pm6

@@ -0,0 +1,9 @@
+use v6;
+unit module GH2897-B;
+use GH2897-A;
+
+our &my-counter is export;
+
+BEGIN {
+    &my-counter = gen-counter;
+}