Update Bio::EnsEMBL::Exon->is_coding():

- Update documentation on required parameters
- Throw an error if a Transcript isn't given
- Add a test for regression

modules/Bio/EnsEMBL/Exon.pm

@@ -1281,8 +1281,7 @@ sub is_constitutive {
 
 =head2 is_coding
 
-  Arg [1]    : Boolean $is_coding
-  Arg [2]    : Bio::EnsEMBL::Transcript
+  Arg [1]    : Bio::EnsEMBL::Transcript
   Example    : $exon->is_coding()
   Description: Says if the exon is within the translation or not
   Returntype : Int
@@ -1295,6 +1294,8 @@ sub is_constitutive {
 sub is_coding {
   my ( $self, $transcript) = @_;
 
+  if (!$transcript) { throw("Transcript parameter is required for " . __PACKAGE__ . "->is_coding()."); }
+
   if (!$transcript->translate) { return 0; }
 
   # coding region overlaps start of exon

modules/t/exon.t

@@ -76,6 +76,9 @@ ok(&test_getter_setter($exon, 'end_phase', 1));
 ok( test_getter_setter( $exon, "created_date", time() ));
 ok( test_getter_setter( $exon, "modified_date", time() ));
 
+# Test that no parameter to is_coding() throws an exception
+throws_ok { $exon->is_coding() } qr/parameter is required/, "Transcript parameter required for is_coding()";
+
 #
 # find supporting evidence for the exon
 #