A bunch of tests for when is/isn't OK.

We leave the given/for/CATCH/CONTROL cases to the many existing tests.

S04-statements/when.t

@@ -0,0 +1,55 @@
+use Test;
+
+plan 24;
+
+throws_like 'when 1 { }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in mainline complains about missing topicalizer';
+throws_like 'default { }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in mainline complains about missing topicalizer';
+
+throws_like '-> { when 1 { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in pointy not declaring $_ complains about missing topicalizer';
+throws_like '-> { default { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in pointy not declaring $_ complains about missing topicalizer';
+
+throws_like 'given 42 -> $a { when 1 { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in pointy on given not declaring $_ complains about missing topicalizer';
+throws_like 'given 42 -> $a { default { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in pointy on given not declaring $_ complains about missing topicalizer';
+
+throws_like 'for 1, 2, 3 -> $a { when 1 { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in pointy on for loop not declaring $_ complains about missing topicalizer';
+throws_like 'for 1, 2, 3 -> $a { default { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in pointy on for loop not declaring $_ complains about missing topicalizer';
+
+throws_like 'sub foo() { when 1 { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in sub not declaring $_ complains about missing topicalizer';
+throws_like 'sub foo() { default { } }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in sub not declaring $_ complains about missing topicalizer';
+
+throws_like 'my class C { method foo() { when 1 { } } }', X::Syntax::OutsideOfTopicalizer, keyword => 'when',
+    'when block in method not declaring $_ complains about missing topicalizer';
+throws_like 'my class C { method foo() { default { } } }', X::Syntax::OutsideOfTopicalizer, keyword => 'default',
+    'default block in method not declaring $_ complains about missing topicalizer';
+
+my $c = { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } };
+is $c(1), 'one', 'when works in a circumfix:<{ }> (1)';
+is $c(2), 'two!', 'when works in a circumfix:<{ }> (2)';
+is $c(3), 'many', 'default works in a circumfix:<{ }>';
+
+my $p = -> $_ { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } };
+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 $_';
+
+sub foo($_) { 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 $_';
+
+class C {
+    method m($_) { when 1 { 'one' }; when 2 { 'two!' }; default { 'many' } }
+}
+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 $_';