tle2toczml

TLE2ToCZML/node_modules/julian/test/test.js

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+var test = require('tap').test;
+
+var julian = require('..');
+
+test('from Date to JD', function (t) {
+  t.equal(julian(new Date(0)), '2440587.500000', 'unix epoch');
+  t.equal(julian(new Date('2000-01-01T12:00:00.000Z')), '2451545.000000', 'noon of Jan 1, 2000');
+
+  t.equal(julian(new Date('2013-01-01T00:30:00.000Z')), '2456293.520833');
+
+  t.end();
+});
+
+test('from JD to Date', function (t) {
+  t.equal(+julian.toDate('2440587.500000'), +new Date(0), 'unix epoch');
+  t.equal(+julian.toDate('2451545.000000'), +new Date('2000-01-01T12:00:00.000Z'), 'noon of Jan 1, 2000');
+
+  t.end();
+});
+
+test('convert back and forth without floating point errors', function (t) {
+  var now = new Date();
+
+  t.equal(+
+    julian.fromJulianDayAndMilliseconds(
+      julian.toJulianDay(now),
+      julian.toMillisecondsInJulianDay(now)
+    ),
+    +now,
+    'now is converted to julian and back safely'
+  );
+
+  t.equal(
+    julian.toMillisecondsInJulianDay(new Date('2000-01-01T12:00:00.000Z')),
+    0,
+    'the day starts at noon, so noon is zero milliseconds'
+  );
+
+  t.equal(
+    julian.toJulianDay(new Date('1970-01-01T00:00:00.000Z')),
+    2440587,
+    'unix epoch starts on julian day 2440587'
+  );
+
+  t.equal(
+    julian.toMillisecondsInJulianDay(new Date('1970-01-01T00:00:00.000Z')),
+    43200000,
+    'unix epoch starts with half a julian day'
+  );
+
+  t.equal(
+    julian.toJulianDay(new Date('1970-01-01T12:00:00.000Z')),
+    2440588,
+    'first noon in unix epoch starts julian day 2440588'
+  );
+
+  t.equal(
+    julian.toMillisecondsInJulianDay(new Date('1970-01-01T12:00:00.000Z')),
+    0,
+    'unix epoch starts with half a julian day'
+  );
+
+  //the instance in time known as j2000, aka terriestial time
+  t.equal(
+    julian.toJulianDay(new Date('2000-01-01T12:00:00.000Z')),
+    2451545,
+    'toJulianDay is give correct julian day for j2000 epoch'
+  );
+  // test data taken from https://en.wikipedia.org/wiki/Epoch_(astronomy)#Julian_years_and_J2000
+
+  t.end();
+
+});