[spec] test for $_ being treated as formal parameter of a block

git-svn-id: http://svn.pugscode.org/pugs@21067 c213334d-75ef-0310-aa23-eaa082d1ae64

S04-declarations/implicit-parameter.t

@@ -0,0 +1,18 @@
+use v6;
+use Test;
+plan 2;
+
+# L<S04/The Relationship of Blocks and Declarations/"A bare closure without
+# placeholder arguments that uses $_">
+
+{
+    # test with explicit $_
+    my $f1 = { 2*$_ };
+    is $f1(2), 4, 'Block with explit $_ has one formal paramter';
+}
+
+{
+    # test with implicit $_
+    my $f2 = { .sqrt };
+    is_approx $f2(4), 2, 'Block with implict $_ has one formal parameter';
+}