1 files changed, 78 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/dom/documents/resource-metadata-management/support/document-lastModified-utils.js b/testing/web-platform/tests/html/dom/documents/resource-metadata-management/support/document-lastModified-utils.js
new file mode 100644
index 0000000000..bbcde1894a
--- /dev/null
+++ b/testing/web-platform/tests/html/dom/documents/resource-metadata-management/support/document-lastModified-utils.js
@@ -0,0 +1,78 @@
+const DOCUMENT_LASTMODIFIED_REGEX = /^([0-9]{2})\/([0-9]{2})\/([0-9]{4}) ([0-9]{2}):([0-9]{2}):([0-9]{2})$/;
+
+function assert_document_lastmodified_string_approximately_now(str) {
+  // We want to test that |str| was a time in the user's local
+  // timezone generated within a few seconds prior to the present.
+  // This requires some care, since it is possible that:
+  //  - the few second difference may have crossed a
+  //    year/month/day/hour/minute boundary
+  //  - the few second difference may have crossed a change in the
+  //    local timezone's UTC offset
+  //  - the local time might be one that has multiple valid UTC
+  //    representations (for example, because it's in the hour
+  //    following a shift from summer time to winter time)
+  // We will make some assumptions to do this:
+  //  - local time's UTC offset doesn't change more than once per
+  //    minute
+  //  - local time's UTC offset only changes by integral numbers of
+  //    minutes
+
+  // The date must be equal to or earlier than the present time.
+  var dmax = new Date();
+
+  // The date must be equal to or later than 2.5 seconds ago.
+  var TOLERANCE_MILLISECONDS = 2500;
+  var dmin = new Date();
+  dmin.setTime(dmax.getTime() - TOLERANCE_MILLISECONDS);
+
+  // Extract the year/month/date/hours/minutes/seconds from str.  It
+  // is important that we do *not* try to construct a Date object from
+  // these, since the core of the date object is a timestamp in UTC,
+  // and there are cases (such as the hour on each side of a change
+  // from summer time to winter time) where there are multiple
+  // possible UTC timestamps for a given YYYY-MM-DD HH:MM:SS, and
+  // constructing a Date object would pick one of them, which might be
+  // the wrong one.  However, we already have the right one in dmin
+  // and dmax, so we should instead extract local time from those
+  // rather than converting these values to UTC.
+  var m = DOCUMENT_LASTMODIFIED_REGEX.exec(str);
+  var syear = Number(m[3]);
+  var smonth = Number(m[1]) - 1; // match Javascript 0-based months
+  var sdate = Number(m[2]);
+  var shours = Number(m[4]);
+  var sminutes = Number(m[5]);
+  var sseconds = Number(m[6]);
+
+  if (dmin.getFullYear() == dmax.getFullYear() &&
+      dmin.getMonth() == dmax.getMonth() &&
+      dmin.getDate() == dmax.getDate() &&
+      dmin.getHours() == dmax.getHours() &&
+      dmin.getMinutes() == dmax.getMinutes()) {
+    // min and max have the same minute
+    assert_equals(smonth, dmin.getMonth(), "month");
+    assert_equals(sdate, dmin.getDate(), "date");
+    assert_equals(syear, dmin.getFullYear(), "year");
+    assert_equals(shours, dmin.getHours(), "hours");
+    assert_equals(sminutes, dmin.getMinutes(), "minutes");
+    assert_true(dmin.getSeconds() <= sseconds &&
+                sseconds <= dmax.getSeconds(), "seconds");
+  } else if (dmin.getFullYear() == syear &&
+             dmin.getMonth() == smonth &&
+             dmin.getDate() == sdate &&
+             dmin.getHours() == shours &&
+             dmin.getMinutes() == sminutes) {
+    // actual value has the same minute as min
+    assert_true(dmin.getSeconds() <= sseconds, "dmin.getSeconds() <= sseconds");
+    assert_true(57 <= dmin.getSeconds(), "unexpected local time rules (dmin match)");
+  } else if (dmax.getFullYear() == syear &&
+             dmax.getMonth() == smonth &&
+             dmax.getDate() == sdate &&
+             dmax.getHours() == shours &&
+             dmax.getMinutes() == sminutes) {
+    // actual value has the same minute as max
+    assert_true(sseconds <= dmax.getSeconds(), "sseconds <= dmax.getSeconds()");
+    assert_true(dmax.getSeconds() <= 2, "unexpected local time rules (dmax match)");
+  } else {
+    assert_unreached("unexpected local time rules (no match)");
+  }
+}