jsonfmt: Add TO_JSON convert_blessed support

t/json_format.t

@@ -5,19 +5,24 @@ use Tie::Array;
 use Tie::Hash;
 use FU::Util 'json_format';
 
-# TODO: gab some more tests from other JSON libs
-# TODO: Test invalid utf8
+
+sub MyToJSON::TO_JSON { [scalar @_, ref $_[0], ${$_[0]}] }
+sub MyToJSONSelf::TO_JSON { $_[0] }
 
 my @tests = (
     undef, 'null',
     true, 'true',
     false, 'false',
-    0, '0',
-    1, '1',
-    -1, '-1',
-    -9223372036854775808, '-9223372036854775808',
-    9223372036854775807, '9223372036854775807',
-    18446744073709551615, '18446744073709551615',
+    (map +($_, $_),
+        -1000..1000,
+        12345, 123456, 1234567,
+        98765, 987654, 9876543,
+        -12345, -123456, -1234567,
+        -98765, -987654, -9876543,
+        -9223372036854775808,
+        9223372036854775807,
+        18446744073709551615,
+    ),
     0.1, '0.1',
     0.000123, '0.000123',
     -1e100, '-1e+100',
@@ -42,6 +47,9 @@ my @tests = (
     do { tie my %h, 'Tie::StdHash'; %h = ('a',1); \%h }, '{"a":1}',
     do { tie my %h, 'MyOrderedHash', one => 1, two => undef, three => []; \%h }, '{"one":1,"two":null,"three":[]}',
 
+    do { my $o = [true]; bless \$o, 'MyToJSON' }, '[1,"MyToJSON",[true]]',
+    do { my $x = [true]; my $o = [bless \$x, 'MyToJSON']; bless \$o, 'MyToJSON' }, '[1,"MyToJSON",[[1,"MyToJSON",[true]]]]',
+
     # from http://e-choroba.eu/18-yapc
     $$, $$,
     ''.$$, '"'.$$.'"',
@@ -56,6 +64,8 @@ my @errors = (
     'NaN'+0, qr/unable to format floating point NaN or Inf as JSON/,
     'Inf'+0, qr/unable to format floating point NaN or Inf as JSON/,
     do { no warnings 'portable'; "\x{ffffffff}" }, qr/invalid codepoint encountered in string/,
+    do { my $o = {}; bless $o, 'FU::Whatever' }, qr/unable to format 'FU::Whatever' object as JSON/,
+    do { my $o = {}; bless $o, 'MyToJSONSelf' }, qr/MyToJSONSelf::TO_JSON method returned same object as was passed instead of a new one/,
 );
 
 plan tests => @tests*2 + @errors/2 + 6;