Add tests for subs on multi-dim arrays.

To complement the methods tests, and make sure we don't have any
divergences in behavior. (We do, as noted in RT #126799, in reverse;
this is being patched. But this shows that in all the other cases we
are already doing the righ thting.)

S09-multidim/subs.t

@@ -0,0 +1,77 @@
+use v6;
+use Test;
+
+plan 38;
+
+# Object array
+{
+    my @arr := Array.new(:shape(2;2));
+
+    is elems(@arr), 2, 'elems is size of first dimensions';
+
+    ok (eager @arr) === @arr, 'eager is identity on a shaped array';
+    lives-ok { sink @arr }, 'sink lives on a shaped array';
+
+    throws-like { push @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'push';
+    throws-like { append @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'append';
+    throws-like { pop @arr }, X::IllegalOnFixedDimensionArray, operation => 'pop';
+    throws-like { unshift @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'unshift';
+    throws-like { prepend @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'prepend';
+    throws-like { shift @arr }, X::IllegalOnFixedDimensionArray, operation => 'shift';
+    throws-like { splice @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'splice';
+    throws-like { reverse @arr }, X::IllegalOnFixedDimensionArray, operation => 'reverse';
+    throws-like { rotate @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'rotate';
+
+    @arr[0;0] = 'a';
+    @arr[0;1] = 'b';
+    @arr[1;0] = 'c';
+    @arr[1;1] = 'd';
+    is keys(@arr), ((0,0), (0, 1), (1, 0), (1, 1)), '.keys on 2-dim gives list of lists of indices';
+    is values(@arr), <a b c d>, '.values on 2x2 array gives 4 leaf values';
+    is kv(@arr), ((0, 0), 'a', (0, 1), 'b', (1, 0), 'c', (1, 1), 'd'),
+        '.kv on a 2x2 array gives list with indice pairs and values interwoven';
+    is pairs(@arr), ((0, 0) => 'a', (0, 1) => 'b', (1, 0) => 'c', (1, 1) => 'd'),
+        '.pairs on a 2x2 array gives list of pairs mapping indice lists to values';
+
+    is keys(Array.new(:shape(4))), (0, 1, 2, 3), '.keys on 1-dim gives list of indices';
+
+    is flat(@arr), <a b c d>, '.flat gives the leaves';
+    is join(',', @arr), 'a,b,c,d', '.join is over leaves';
+}
+
+# Native array
+{
+    my @arr := array[int].new(:shape(2;2));
+
+    is elems(@arr), 2, 'elems is size of first dimensions (native)';
+
+    ok (eager @arr) === @arr, 'eager is identity on a shaped array (native)';
+    lives-ok { sink @arr }, 'sink lives on a shaped array (native)';
+
+    throws-like { push @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'push';
+    throws-like { append @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'append';
+    throws-like { pop @arr }, X::IllegalOnFixedDimensionArray, operation => 'pop';
+    throws-like { unshift @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'unshift';
+    throws-like { prepend @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'prepend';
+    throws-like { shift @arr }, X::IllegalOnFixedDimensionArray, operation => 'shift';
+    throws-like { splice @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'splice';
+    throws-like { reverse @arr }, X::IllegalOnFixedDimensionArray, operation => 'reverse';
+    throws-like { rotate @arr, 1 }, X::IllegalOnFixedDimensionArray, operation => 'rotate';
+
+    @arr[0;0] = 42;
+    @arr[0;1] = 43;
+    @arr[1;0] = 44;
+    @arr[1;1] = 45;
+    is keys(@arr), ((0,0), (0, 1), (1, 0), (1, 1)),
+        '.keys on 2-dim gives list of lists of indices (native)';
+    is values(@arr), (42, 43, 44, 45), '.values on 2x2 array gives 4 leaf values (native)';
+    is kv(@arr), ((0, 0), 42, (0, 1), 43, (1, 0), 44, (1, 1), 45),
+        '.kv on a 2x2 array gives list with indice pairs and values interwoven (native)';
+    is pairs(@arr), ((0, 0) => 42, (0, 1) => 43, (1, 0) => 44, (1, 1) => 45),
+        '.pairs on a 2x2 array gives list of pairs mapping indice lists to values (native)';
+
+    is keys(array[int].new(:shape(4))), (0, 1, 2, 3), '.keys on 1-dim gives list of indices (native)';
+
+    is flat(@arr), (42, 43, 44, 45), '.flat gives the leaves (native)';
+    is join(',', @arr), '42,43,44,45', '.join is over leaves (native)';
+}