Fix Date.prototype.toString() and toISOString() (#3175)

The implementation was incorrect for negative years and years bigger than 9999.
-1 was 000/ because the negative (year%10) was added to '0' character, years
bigger than 9999 was truncated to 4 digits.

ES5.1 15.9.1.15.1 defines extended years format with 6 digits, but toString()
and toISOString() sections don't mention anything about extended years. ES6
20.3.4.3 already clarifies that Date.prototype.toISOString() should use this
extended year format if it is necessary.

Changes:
- Date.prototype.toString() uses 4 digits for years by default, 5 or 6 if it
is necessary and put '-' sign for negative years, no sign for positive years.
Date.prototype.toString() was implementation dependent until ES9, but ES9
already specify exactly this format.
- Date.prototype.toISOString() uses fixed 4 digits for years 0 - 9999,
otherwise sign + 6 digits (extended years).
- Tests added for corner cases.

JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác oszi@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-helpers-date.c

@@ -587,7 +587,7 @@ ecma_date_to_string_format (ecma_number_t datetime_number, /**< datetime */
     "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
   };
 
-  const uint32_t date_buffer_length = 34;
+  const uint32_t date_buffer_length = 37;
   JERRY_VLA (lit_utf8_byte_t, date_buffer, date_buffer_length);
 
   lit_utf8_byte_t *dest_p = date_buffer;
@@ -611,7 +611,32 @@ ecma_date_to_string_format (ecma_number_t datetime_number, /**< datetime */
       case LIT_CHAR_UPPERCASE_Y: /* Year. */
       {
         number = (int32_t) ecma_date_year_from_time (datetime_number);
-        number_length = 4;
+
+        if (number >= 100000 || number <= -100000)
+        {
+          number_length = 6;
+        }
+        else if (number >= 10000 || number <= -10000)
+        {
+          number_length = 5;
+        }
+        else
+        {
+          number_length = 4;
+        }
+        break;
+      }
+      case LIT_CHAR_LOWERCASE_Y: /* ISO Year: -000001, 0000, 0001, 9999, +012345 */
+      {
+        number = (int32_t) ecma_date_year_from_time (datetime_number);
+        if (0 <= number && number <= 9999)
+        {
+          number_length = 4;
+        }
+        else
+        {
+          number_length = 6;
+        }
         break;
       }
       case LIT_CHAR_UPPERCASE_M: /* Month. */
@@ -723,6 +748,17 @@ ecma_date_to_string_format (ecma_number_t datetime_number, /**< datetime */
     /* Print right aligned number values. */
     JERRY_ASSERT (number_length > 0);
 
+    if (number < 0)
+    {
+      number = -number;
+      *dest_p++ = '-';
+    }
+    else if (*(format_p - 1) == LIT_CHAR_LOWERCASE_Y && number_length == 6)
+    {
+      /* positive sign is compulsory for extended years */
+      *dest_p++ = '+';
+    }
+
     dest_p += number_length;
     lit_utf8_byte_t *buffer_p = dest_p;
 
@@ -785,7 +821,7 @@ ecma_date_value_to_utc_string (ecma_number_t datetime_number) /**< datetime */
 ecma_value_t
 ecma_date_value_to_iso_string (ecma_number_t datetime_number) /**<datetime */
 {
-  return ecma_date_to_string_format (datetime_number, "$Y-$O-$DT$h:$m:$s.$iZ");
+  return ecma_date_to_string_format (datetime_number, "$y-$O-$DT$h:$m:$s.$iZ");
 } /* ecma_date_value_to_iso_string */
 
 /**

tests/jerry/date-toisostring.js

@@ -0,0 +1,54 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+try {
+    d = new Date (-8640000000000001)
+    assert (d == "Invalid Date")
+    d.toISOString()
+    assert(false);
+} catch (e) {
+    assert(e instanceof RangeError)
+}
+
+assert (new Date (-8640000000000000).toISOString() == "-271821-04-20T00:00:00.000Z")
+
+assert (new Date(-62167219200001).toISOString() == "-000001-12-31T23:59:59.999Z")
+assert (new Date(-62167219200000).toISOString() == "0000-01-01T00:00:00.000Z")
+
+assert (new Date(-61851600000001).toISOString() == "0009-12-31T23:59:59.999Z")
+assert (new Date(-61851600000000).toISOString() == "0010-01-01T00:00:00.000Z")
+
+assert (new Date(-59011459200001).toISOString() == "0099-12-31T23:59:59.999Z")
+assert (new Date(-59011459200000).toISOString() == "0100-01-01T00:00:00.000Z")
+
+assert (new Date(-30610224000001).toISOString() == "0999-12-31T23:59:59.999Z")
+assert (new Date(-30610224000000).toISOString() == "1000-01-01T00:00:00.000Z")
+
+assert (new Date(-1).toISOString() == "1969-12-31T23:59:59.999Z")
+assert (new Date(0).toISOString() == "1970-01-01T00:00:00.000Z")
+assert (new Date(1).toISOString() == "1970-01-01T00:00:00.001Z")
+
+assert (new Date(253402300799999).toISOString() == "9999-12-31T23:59:59.999Z")
+assert (new Date(253402300800000).toISOString() == "+010000-01-01T00:00:00.000Z")
+
+assert (new Date (8640000000000000).toISOString() == "+275760-09-13T00:00:00.000Z")
+
+try {
+    d = new Date (8640000000000001)
+    assert (d == "Invalid Date")
+    d.toISOString()
+    assert(false);
+} catch (e) {
+    assert(e instanceof RangeError)
+}

tests/jerry/date-tostring.js

@@ -142,3 +142,29 @@ assert (Date (2015, 1, 1) == (new Date ()).toString ());
 assert (Date (Number.NaN) == Date ());
 
 assert (new Date ("2015-07-08T11:29:05.023Z").toISOString() == "2015-07-08T11:29:05.023Z");
+
+// corner cases
+assert (new Date (-8640000000000001).toString() == "Invalid Date")
+assert (new Date (-8640000000000000).toString() == "Tue Apr 20 -271821 00:00:00 GMT+00:00")
+
+assert (new Date(-62167219200001).toString() == "Fri Dec 31 -0001 23:59:59 GMT+00:00")
+assert (new Date(-62167219200000).toString() == "Sat Jan 01 0000 00:00:00 GMT+00:00")
+
+assert (new Date(-61851600000001).toString() == "Thu Dec 31 0009 23:59:59 GMT+00:00")
+assert (new Date(-61851600000000).toString() == "Fri Jan 01 0010 00:00:00 GMT+00:00")
+
+assert (new Date(-59011459200001).toString() == "Thu Dec 31 0099 23:59:59 GMT+00:00")
+assert (new Date(-59011459200000).toString() == "Fri Jan 01 0100 00:00:00 GMT+00:00")
+
+assert (new Date(-30610224000001).toString() == "Tue Dec 31 0999 23:59:59 GMT+00:00")
+assert (new Date(-30610224000000).toString() == "Wed Jan 01 1000 00:00:00 GMT+00:00")
+
+assert (new Date(-1).toString() == "Wed Dec 31 1969 23:59:59 GMT+00:00")
+assert (new Date(0).toString() == "Thu Jan 01 1970 00:00:00 GMT+00:00")
+assert (new Date(1).toString() == "Thu Jan 01 1970 00:00:00 GMT+00:00")
+
+assert (new Date(253402300799999).toString() == "Fri Dec 31 9999 23:59:59 GMT+00:00")
+assert (new Date(253402300800000).toString() == "Sat Jan 01 10000 00:00:00 GMT+00:00")
+
+assert (new Date (8640000000000000).toString() == "Sat Sep 13 275760 00:00:00 GMT+00:00")
+assert (new Date (8640000000000001).toString() == "Invalid Date")