mail: do not return an error if header field is missing in Header.AddressList

Author: emersion

mail/header.go

@@ -20,9 +20,14 @@ func NewHeader() Header {
 	return Header{make(message.Header)}
 }
 
-// AddressList parses the named header field as a list of addresses.
+// AddressList parses the named header field as a list of addresses. If the
+// header is missing, it returns nil.
 func (h Header) AddressList(key string) ([]*Address, error) {
-	return parseAddressList(h.Get(key))
+	v := h.Get(key)
+	if v == "" {
+		return nil, nil
+	}
+	return parseAddressList(v)
 }
 
 // SetAddressList formats the named header to the provided list of addresses.

mail/header_test.go

@@ -30,6 +30,12 @@ func TestHeader(t *testing.T) {
 		t.Errorf("Expected header address list to be %v, but got %v", from, got)
 	}
 
+	if got, err := h.AddressList("Cc"); err != nil {
+		t.Error("Expected no error while parsing missing header address list, got:", err)
+	} else if got != nil {
+		t.Errorf("Expected missing header address list to be %v, but got %v", nil, got)
+	}
+
 	if got, err := h.Subject(); err != nil {
 		t.Error("Expected no error while parsing header subject, got:", err)
 	} else if got != subject {