Improve support for "has" in Dancer2::Plugin

lib/Dancer2/Plugin.pm

@@ -342,8 +342,18 @@ sub _exporter_plugin {
             our \@EXPORT = ( ':app' );
 
             around has => sub {
-                my( \$orig, \@args ) = \@_;
-                \$orig->( ${caller}->_p2_has( \@args) );
+                my( \$orig, \$name, \%args ) = \@_;
+
+                if (ref \$name eq 'ARRAY'
+                        && exists \$args{'plugin_keyword'}
+                        && ref \$args{'plugin_keyword'} eq 'ARRAY') {
+
+                    Carp::croak('Setting "plugin_keyword" to an array is disallowed'
+                        . ' when defining multiple attributes simultaneously');
+                }
+
+                \$orig->( ${caller}->_p2_has( \$_, \%args) )
+                    for ref \$name ? @\$name : \$name;
             };
 
             sub PluginKeyword :ATTR(CODE,BEGIN) {

t/plugin2/from-config.t

@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 
-use Test::More tests => 5;
+use Test::More tests => 8;
 
 {
 package Dancer2::Plugin::FromConfig;
@@ -37,6 +37,21 @@ has six => (
     plugin_keyword => 1,
 );
 
+has [qw(seven eight)] => (
+    is => 'ro',
+    from_config => 1,
+    plugin_keyword => 1,
+);
+
+eval {
+    has [qw(nine ten)] => (
+        is => 'ro',
+        from_config => 1,
+        plugin_keyword => ['nine', 'ten'],
+    );
+};
+our $plugin_keyword_exception = $@;
+
 plugin_keywords qw/ one three four five /;
 
 }
@@ -54,7 +69,9 @@ plugin_keywords qw/ one three four five /;
             one => 'un',
             two => {
                 three => 'trois',
-            }
+            },
+            seven => 'sept',
+            eight => 'huit',
         }
     };
 
@@ -64,6 +81,11 @@ plugin_keywords qw/ one three four five /;
     Test::More::is four() => 'quatre', 'nothing in config, default value';
     Test::More::is five() => 'cinq', 'from_config a coderef';
     Test::More::is six() => 'AH!', 'from_config a coderef, no override';
+    Test::More::is seven() => 'sept', 'from_config, defined two fields at once #1';
+    Test::More::is eight() => 'huit', 'from_config, defined two fields at once #2';
+    Test::More::ok $Dancer2::Plugin::FromConfig::plugin_keyword_exception,
+        "defining two fields simultaneously with multiple plugin_keyword values"
+        . " is disallowed";
 }