Many more "on" tests and fudge Supply.(zip|merge)

Oddly enough, identical implementations of .zip and .merge work in the test,
but not when they're pre-compiled in the settings.  Go figure  :-(

S17-concurrency/supply.t

@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 140;
+plan 170;
 
 sub tap_ok ( $s, $expected, $text ) {
     ok $s ~~ Supply, "{$s.^name} appears to be doing Supply";
@@ -10,7 +10,7 @@ sub tap_ok ( $s, $expected, $text ) {
     my $done;
     $s.tap({ @res.push($_) }, :done( {$done = True} ));
 
-    for ^50 { sleep .1; last if $done }
+    for ^50 { sleep .1; last if $done or $s.done }
     ok $done, "$text was really done";
     is_deeply @res, $expected, $text;
 }
@@ -144,6 +144,88 @@ for (ThreadPoolScheduler, CurrentThreadScheduler) {
       "squish with as and with tap works";
 
     {
+        my $s1 = Supply.for(1..10);
+        my $on = on -> $res {
+            $s1 => sub ($val) {
+                $res.more($val);
+            }
+        }
+        tap_ok $on, [1..10], "minimal 'on' works";
+    }
+
+    {
+        my $s1 = Supply.for("a".."j");
+        my $s2 = Supply.for(1..10);
+        my $on = on -> $res {
+            my @a1;
+            my @a2;
+            $s1 => sub ($val) {
+                @a1.push($val);
+                if @a1 && @a2 {
+                    $res.more( (@a1.shift => @a2.shift) );
+                }
+            },
+            $s2 => -> \val {
+                @a2.push(val);
+                if @a1 && @a2 {
+                    $res.more( @a1.shift => @a2.shift );
+                }
+            }
+        }
+        tap_ok $on,
+          [:a(1),:b(2),:c(3),:d(4),:e(5),:f(6),:g(7),:h(8),:i(9),:j(10)],
+          "basic 2 supply 'on' works";
+    }
+
+    {
+        my $a = Supply.for("a".."e");
+        my $b = Supply.for("f".."k");
+        my $on = on -> $res {
+            my @values = ([],[]);
+            ($a,$b) => sub ($val,$index) {
+                @values[$index].push($val);
+                if all(@values) {
+                    $res.more( (@values>>.shift) );
+                }
+            }
+        }
+        tap_ok $on,
+          [<a f>,<b g>,<c h>,<d i>,<e j>],
+          "basic 2 supply with (a,b) 'on' works";
+    }
+
+    {
+        my @s=(Supply.for("a".."e"),Supply.for("f".."k"),Supply.for("l".."p"));
+        my $on = on -> $res {
+            my @values = ([] xx +@s);
+            my &infix:<op> = &[,];
+            @s => -> \val, \index {
+                @values[index].push(val);
+                if all(@values) {
+                    $res.more( [op] @values>>.shift );
+                }
+            }
+        }
+        tap_ok $on,
+          [<a f l>,<b g m>,<c h n>,<d i o>,<e j p>],
+          "basic 3 supply with array 'on' works";
+    }
+
+    {
+        my @s = ( Supply.for("a".."e"), Supply.for("f".."k") );
+        my @seen;
+        my $on = on -> $res {
+            my $done = 0;
+            @s => {
+              more => sub ($val) { @seen.push($val); $res.more($val) },
+              done => { $res.done if ++$done == +@s }
+            }
+        }
+        tap_ok $on, @seen, "basic 2 supply with array without index 'on' works";
+    }
+
+#?rakudo skip "Cannot stringify this"
+{
         my $s1 = Supply.new;
         my $s2 = Supply.new;
 
@@ -159,9 +241,9 @@ for (ThreadPoolScheduler, CurrentThreadScheduler) {
         $s2.done();
 
         is_deeply @res, [<1a 2b>], 'zipping taps works';
-    }
+}
 
-#?rakudo skip "Cannot call method 'more' on a null object"
+#?rakudo skip "Cannot stringify this"
 {
         my $done = False;
         my $s1 = Supply.new;