1 files changed, 29 insertions, 0 deletions
diff --git a/js/src/tests/non262/Date/time-zone-etc_localetime.js b/js/src/tests/non262/Date/time-zone-etc_localetime.js
new file mode 100644
index 0000000000..eaf8f7d940
--- /dev/null
+++ b/js/src/tests/non262/Date/time-zone-etc_localetime.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(xulRuntime.OS=="WINNT"||!xulRuntime.shell)
+
+assertEq(/^(PST|PDT)$/.test(getTimeZone()), true,
+         "The default time zone is set to PST8PDT for all jstests (when run in the shell)");
+
+function timeZoneName() {
+    var dtf = new Intl.DateTimeFormat("en-US", {timeZoneName: "long"});
+    return dtf.formatToParts().filter(x => x.type === "timeZoneName")[0].value;
+}
+
+// Calling setTimeZone() with an undefined argument clears the TZ environment
+// variable and by that reveal the actual system time zone.
+setTimeZone(undefined);
+var systemTimeZone = getTimeZone();
+var systemTimeZoneName = timeZoneName();
+
+// Set to an unlikely system time zone, so that the next call to setTimeZone()
+// will lead to a time zone change.
+setTimeZone("Antarctica/Troll");
+
+// Now call with the file path ":/etc/localtime" which is special-cased in
+// DateTimeInfo to read the system time zone.
+setTimeZone(":/etc/localtime");
+
+assertEq(getTimeZone(), systemTimeZone);
+assertEq(timeZoneName(), systemTimeZoneName);
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);