diff --git a/test/harness/dateConstants.js b/test/harness/dateConstants.js
new file mode 100644
index 0000000000000000000000000000000000000000..265186aef1fc6178aa2168e8dea06edc76a721b5
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+++ b/test/harness/dateConstants.js
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+// Copyright (c) 2017 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: >
+    Including dateConstants.js will expose:
+
+        var date_1899_end = -2208988800001;
+        var date_1900_start = -2208988800000;
+        var date_1969_end = -1;
+        var date_1970_start = 0;
+        var date_1999_end = 946684799999;
+        var date_2000_start = 946684800000;
+        var date_2099_end = 4102444799999;
+        var date_2100_start = 4102444800000;
+
+includes: [dateConstants.js]
+---*/
+assert.sameValue(date_1899_end, -2208988800001);
+assert.sameValue(date_1900_start, -2208988800000);
+assert.sameValue(date_1969_end, -1);
+assert.sameValue(date_1970_start, 0);
+assert.sameValue(date_1999_end, 946684799999);
+assert.sameValue(date_2000_start, 946684800000);
+assert.sameValue(date_2099_end, 4102444799999);
+assert.sameValue(date_2100_start, 4102444800000);