Fix and test the TimeValue.pad() function

Author: thiemowmde

src/values/TimeValue.js

@@ -336,7 +336,12 @@ SELF.getPrecisionById = function( id ) {
  * @return {string}
  */
 function pad( number, digits ) {
-	return ( ( 1e12 + Math.abs( number ) ).toString() ).slice( -digits );
+	number = String( Math.abs( number ) );
+	if ( number.length >= digits ) {
+		return number;
+	}
+
+	return new Array( digits - number.length + 1 ).join( '0' ) + number;
 }
 
 dv.registerDataValue( SELF );

tests/src/values/TimeValue.tests.js

@@ -43,6 +43,35 @@ define( [
 					precision: 9
 				}]
 			];
+		},
+
+		/**
+		 * Tests the effect of the private pad() function, relevant in getSortKey() and toJSON().
+		 *
+		 * @since 0.7
+		 *
+		 * @param {QUnit} assert
+		 */
+		testPad: function( assert ) {
+			var testCases = {
+				'1-1-1T01:01:01Z': '+00000000001-01-01T01:01:01Z',
+				'12-00-00T00:00:00Z': '+00000000012-00-00T00:00:00Z',
+				'1234567890-00-00T00:00:00Z': '+01234567890-00-00T00:00:00Z',
+				'12345678901-00-00T00:00:00Z': '+12345678901-00-00T00:00:00Z',
+				'123456789012-00-00T00:00:00Z': '+123456789012-00-00T00:00:00Z',
+				'1234567890123456-00-00T00:00:00Z': '+1234567890123456-00-00T00:00:00Z'
+			};
+
+			for( var iso8601 in testCases ) {
+				var expected = testCases[iso8601],
+					actual = new dv.TimeValue( iso8601 ).getSortKey();
+
+				assert.ok(
+					expected === actual,
+					'Expected getSortKey() to return "' + expected + '", got "' + actual + '"'
+				);
+
+			}
 		}
 
 	} );