Document is()'s special treatment of values...

that differ only on whitespace

Author: zoffixznet

doc/Language/testing.pod6

@@ -291,6 +291,13 @@ L«C<is-deeply> routine|/language/testing#index-entry-is-deeply-is-deeply($value
     my Int $a;
     is $a, Int, 'The variable $a is an unassigned Int';
 
+B<Note:> if I<only> whitespace differs between the values, C<is()> will output failure
+message differently, to show the whitespace in each values. For example, in the
+output below, the second test shows the literal C<\t> in the C<got:> line:
+
+    is "foo\tbar", "foo\tbaz";   # expected: 'foo     baz'␤#      got: 'foo   bar'
+    is "foo\tbar", "foo    bar"; # expected: "foo    bar"␤#      got: "foo\tbar"
+    
 =item X<isnt($value, $expected, $description?)|isnt>
 
 Marks a test as passed if C<$value> and C<$expected> are B<not> equal using