add tests for RT #126291

Author: FROGGS

S04-declarations/smiley.t

@@ -1,7 +1,7 @@
 use v6;
 use Test;
 
-plan 57;
+plan 60;
 
 my Int:D $j = 256;
 MY::<$j> = 111;
@@ -142,4 +142,17 @@ throws-like 'use variables :foo',
   name => 'foo',
   'does use variables :foo fail';
 
+# RT #126291
+{
+    my Int:D $x is default(0);
+    is $x, 0, 'Int:D with default value via trait';
+
+    my Int:D @array is default(0); @array[0] = Nil;
+    is @array[0], 0, 'Int:D array with default value via trait';
+
+    throws-like { @array[0] = Int },
+        X::TypeCheck::Assignment,
+        symbol => '@array', 'type check happens for Int:D array';
+}
+
 # vim: ft=perl6