Fix input preparation for date objects with a BC year (#1864)

* test: BC date input preparation

* Fix input preparation for BC dates

Author: noinkling

Diff for: lib/utils.js

@@ -97,7 +97,12 @@ function pad (number, digits) {
 
 function dateToString (date) {
   var offset = -date.getTimezoneOffset()
-  var ret = pad(date.getFullYear(), 4) + '-' +
+
+  var year = date.getFullYear()
+  var isBCYear = year < 1
+  if (isBCYear) year = Math.abs(year) + 1 // negative years are 1 off their BC representation
+
+  var ret = pad(year, 4) + '-' +
     pad(date.getMonth() + 1, 2) + '-' +
     pad(date.getDate(), 2) + 'T' +
     pad(date.getHours(), 2) + ':' +
@@ -110,19 +115,27 @@ function dateToString (date) {
     offset *= -1
   } else { ret += '+' }
 
-  return ret + pad(Math.floor(offset / 60), 2) + ':' + pad(offset % 60, 2)
+  ret += pad(Math.floor(offset / 60), 2) + ':' + pad(offset % 60, 2)
+  if (isBCYear) ret += ' BC'
+  return ret
 }
 
 function dateToStringUTC (date) {
-  var ret = pad(date.getUTCFullYear(), 4) + '-' +
+  var year = date.getUTCFullYear()
+  var isBCYear = year < 1
+  if (isBCYear) year = Math.abs(year) + 1 // negative years are 1 off their BC representation
+
+  var ret = pad(year, 4) + '-' +
     pad(date.getUTCMonth() + 1, 2) + '-' +
     pad(date.getUTCDate(), 2) + 'T' +
     pad(date.getUTCHours(), 2) + ':' +
     pad(date.getUTCMinutes(), 2) + ':' +
     pad(date.getUTCSeconds(), 2) + '.' +
     pad(date.getUTCMilliseconds(), 3)
 
-  return ret + '+00:00'
+  ret += '+00:00'
+  if (isBCYear) ret += ' BC'
+  return ret
 }
 
 function normalizeQueryConfig (config, values, callback) {

Diff for: test/unit/utils-tests.js

@@ -81,6 +81,27 @@ test('prepareValues: date prepared properly as UTC', function () {
   defaults.parseInputDatesAsUTC = false
 })
 
+test('prepareValues: BC date prepared properly', function () {
+  helper.setTimezoneOffset(-330)
+
+  var date = new Date(-3245, 1, 1, 11, 11, 1, 7)
+  var out = utils.prepareValue(date)
+  assert.strictEqual(out, '3246-02-01T11:11:01.007+05:30 BC')
+
+  helper.resetTimezoneOffset()
+})
+
+test('prepareValues: 1 BC date prepared properly', function () {
+  helper.setTimezoneOffset(-330)
+
+  // can't use the multi-argument constructor as year 0 would be interpreted as 1900
+  var date = new Date('0000-02-01T11:11:01.007')
+  var out = utils.prepareValue(date)
+  assert.strictEqual(out, '0001-02-01T11:11:01.007+05:30 BC')
+
+  helper.resetTimezoneOffset()
+})
+
 test('prepareValues: undefined prepared properly', function () {
   var out = utils.prepareValue(void 0)
   assert.strictEqual(out, null)