fix(validator): add fare transfer duration validator

re #167

src/main/java/com/conveyal/gtfs/error/NewGTFSErrorType.java

@@ -12,6 +12,7 @@ public enum NewGTFSErrorType {
     LANGUAGE_FORMAT(Priority.LOW, "Language should be specified with a valid BCP47 tag."),
     ILLEGAL_FIELD_VALUE(Priority.MEDIUM, "Fields may not contain tabs, carriage returns or new lines."),
     INTEGER_FORMAT(Priority.MEDIUM, "Incorrect integer format."),
+    FARE_TRANSFER_MISMATCH(Priority.MEDIUM, "A fare that does not permit transfers has a non-zero transfer duration."),
     FLOATING_FORMAT(Priority.MEDIUM, "Incorrect floating point number format."),
     COLUMN_NAME_UNSAFE(Priority.HIGH, "Column header contains characters not safe in SQL, it was renamed."),
     NUMBER_PARSING(Priority.MEDIUM, "Unable to parse number from value."),

src/main/java/com/conveyal/gtfs/loader/Feed.java

@@ -35,7 +35,7 @@ public class Feed {
     public final TableReader<Agency> agencies;
     public final TableReader<Calendar> calendars;
     public final TableReader<CalendarDate> calendarDates;
-//    public final TableReader<Fare> fares;
+    public final TableReader<FareAttribute> fareAttributes;
     public final TableReader<Route> routes;
     public final TableReader<Stop>  stops;
     public final TableReader<Trip>  trips;
@@ -57,7 +57,7 @@ public Feed (DataSource dataSource, String tablePrefix) {
         if (tablePrefix != null && !tablePrefix.endsWith(".")) tablePrefix += ".";
         this.tablePrefix = tablePrefix == null ? "" : tablePrefix;
         agencies = new JDBCTableReader(Table.AGENCY, dataSource, tablePrefix, EntityPopulator.AGENCY);
-//        fares = new JDBCTableReader(Table.FARES, dataSource, tablePrefix, EntityPopulator.FARE);
+        fareAttributes = new JDBCTableReader(Table.FARE_ATTRIBUTES, dataSource, tablePrefix, EntityPopulator.FARE_ATTRIBUTE);
         calendars = new JDBCTableReader(Table.CALENDAR, dataSource, tablePrefix, EntityPopulator.CALENDAR);
         calendarDates = new JDBCTableReader(Table.CALENDAR_DATES, dataSource, tablePrefix, EntityPopulator.CALENDAR_DATE);
         routes = new JDBCTableReader(Table.ROUTES, dataSource, tablePrefix, EntityPopulator.ROUTE);
@@ -89,6 +89,7 @@ public ValidationResult validate () {
         List<FeedValidator> feedValidators = Arrays.asList(
                 new MisplacedStopValidator(this, errorStorage, validationResult),
                 new DuplicateStopsValidator(this, errorStorage),
+                new FaresValidator(this, errorStorage),
                 new TimeZoneValidator(this, errorStorage),
                 new NewTripTimesValidator(this, errorStorage),
                 new NamesValidator(this, errorStorage));

src/main/java/com/conveyal/gtfs/validator/FaresValidator.java

@@ -0,0 +1,26 @@
+package com.conveyal.gtfs.validator;
+
+import com.conveyal.gtfs.error.NewGTFSErrorType;
+import com.conveyal.gtfs.error.SQLErrorStorage;
+import com.conveyal.gtfs.loader.Feed;
+import com.conveyal.gtfs.model.FareAttribute;
+
+/**
+ * Validator for fares that currently just checks that the transfers and transfer_duration fields are harmonious.
+ */
+public class FaresValidator extends FeedValidator {
+    public FaresValidator(Feed feed, SQLErrorStorage errorStorage) {
+        super(feed, errorStorage);
+    }
+
+    @Override
+    public void validate() {
+        for (FareAttribute fareAttribute : feed.fareAttributes) {
+            if (fareAttribute.transfers == 0 && fareAttribute.transfer_duration > 0) {
+                // If a fare does not permit transfers, but defines a duration for which a transfer is valid, register
+                // an error.
+                registerError(fareAttribute, NewGTFSErrorType.FARE_TRANSFER_MISMATCH);
+            }
+        }
+    }
+}