More tests for when/default.

To exercise semantics update coming in S04 design doc.

S04-statements/when.t

@@ -1,6 +1,6 @@
 use Test;
 
-plan 12;
+plan 18;
 
 my $c = { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } };
 is $c(1), 'one', 'when works in a circumfix:<{ }> (1)';
@@ -12,14 +12,36 @@ is $p(1), 'one', 'when works in a pointy block declaring $_ (1)';
 is $p(2), 'two!', 'when works in a pointy block declaring $_ (2)';
 is $p(3), 'many', 'default works in a pointy block declaring $_';
 
+my $pi = -> { $_ = 4; when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } };
+is $pi(), 'many', 'when works in a pointy block using its implicit $_';
+
 sub foo($_) { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } }
 is foo(1), 'one', 'when works in a sub declaring $_ (1)';
 is foo(2), 'two!', 'when works in a sub declaring $_ (2)';
 is foo(3), 'many', 'default works in a sub declaring $_';
 
+sub bar() { $_ = 2; when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } }
+is bar(), 'two!', 'when works in sub using its implicit $_';
+
 class C {
     method m($_) { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } }
+    method i() { $_ = 1; when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } }
+}
+is C.m(1), 'one', 'when works in a method declaring $_ (1)';
+is C.m(2), 'two!', 'when works in a method declaring $_ (2)';
+is C.m(3), 'many', 'default works in a method declaring $_';
+is C.i, 'one', 'when works in a method using its implicit $_';
+
+my $nest = sub ($n) {
+    $_ = $n * 2;
+    when * > 2 {
+        when 4 { 'four!' }
+        default { 'huge' }
+    }
+    default {
+        'little'
+    }
 }
-is C.m(1), 'one', 'when works in a sub declaring $_ (1)';
-is C.m(2), 'two!', 'when works in a sub declaring $_ (2)';
-is C.m(3), 'many', 'default works in a sub declaring $_';
+is $nest(1), 'little', 'nested when in a sub works (1)';
+is $nest(2), 'four!', 'nested when in a sub works (2)';
+is $nest(3), 'huge', 'nested when in a sub works (3)';