reading tied scalar shrinks it

[p5sagit/Devel-Size.git] / t / magic.t

diff --git a/t/magic.t b/t/magic.t
index d0f5b73..3fa7d05 100644 (file)
--- a/t/magic.t
+++ b/t/magic.t
@@ -1,7 +1,7 @@
 #!/usr/bin/perl -w
 
 use strict;
-use Test::More tests => 7;
+use Test::More tests => 18;
 use Devel::Size ':all';
 require Tie::Scalar;
 
@@ -15,7 +15,12 @@ require Tie::Scalar;
           'size increases due to magic');
 }
 
-{
+SKIP: {
+    # bug in perl added in blead by commit 815f25c6e302f84e, fixed in commit
+    # f5c235e79ea25787, merged to maint-5.8 as 0710cc63c26afd0c and
+    # 8298b2e171ce84cf respectively.
+    skip("This triggers a formline assertion on $]", 4)
+       if $] > 5.008000 && $] < 5.008003;
     my $string = 'Perl Rules';
     my $before_size = total_size($string);
     formline $string;
@@ -31,3 +36,43 @@ require Tie::Scalar;
     cmp_ok($after_size, '>', $before_size, 'Still larger than initial size');
     cmp_ok($after_size, '<', $compiled_size, 'size decreases due to unmagic');
 }
+
+{
+    my $string = 'Perl Rules';
+    my $before_size = total_size($string);
+    cmp_ok($before_size, '>', length $string,
+          'Our string has a non-zero length');
+    tie $string, 'Tie::StdScalar';
+    my $after_size = total_size($string);
+    cmp_ok($after_size, '>', $before_size, 'size increases due to magic');
+    is($string, undef, 'No value yet');
+    my $small_size = total_size($string);
+    # This is defineately cheating, in that we're poking inside the
+    # implementation of Tie::StdScalar, but if we just write to $string, the way
+    # magic works, the (nice long) value is first written to the regular scalar,
+    # then picked up by the magic. So it grows, which defeats the purpose of the
+    # test.
+    ${tied $string} = 'X' x 1024;
+    cmp_ok(total_size($string), '>', $small_size + 1024,
+          'the magic object is counted');
+}
+
+SKIP: {
+    skip("v-strings didn't use magic before 5.8.1", 2) if $] < 5.008001;
+    my $v = eval 'v' . (0 x 1024);
+    is($v, "\0", 'v-string is \0');
+    cmp_ok(total_size($v), '>', 1024, 'total_size follows MG_PTR');
+}
+
+SKIP: {
+    skip("no UTF-8 caching before 5.8.1", 5) if $] < 5.008001;
+    my $string = "a\x{100}b";
+    my $before_size = total_size($string);
+    cmp_ok($before_size, '>', 0, 'Our string has a non-zero length');
+    is(length $string, 3, 'length is sane');
+    my $with_magic = total_size($string);
+    cmp_ok($with_magic, '>', $before_size, 'UTF-8 caching fired and counted');
+    is(index($string, "b"), 2, 'b is where we expect it');
+    cmp_ok(total_size($string), '>', $with_magic,
+          'UTF-8 caching length table now present');
+}