ran npm run tdd & generated TDD

test/elo/elo.js

@@ -0,0 +1,18 @@
+module.exports = ([...ratings], kFactor = 32, selfRating) => {
+const [a, b] = ratings;
+const expectedScore = (self, opponent) => 1 / (1 + 10 ** ((opponent - self) / 400));
+const newRating = (rating, i) =>
+(selfRating || rating) + kFactor * (i - expectedScore(i ? a : b, i ? b : a));
+if (ratings.length === 2) {
+return [newRating(a, 1), newRating(b, 0)];
+} else {
+for (let i = 0; i < ratings.length; i++) {
+let j = i;
+while (j < ratings.length - 1) {
+[ratings[i], ratings[j + 1]] = elo([ratings[i], ratings[j + 1]], kFactor);
+j++;
+}
+}
+}
+return ratings;
+};

test/elo/elo.test.js

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+const test = require('tape');
+const elo = require('./elo.js');
+
+test('Testing elo', (t) => {
+	//For more information on all the methods supported by tape
+	//Please go to https://github.com/substack/tape
+	t.true(typeof elo === 'function', 'elo is a Function');
+	//t.deepEqual(elo(args..), 'Expected');
+	//t.equal(elo(args..), 'Expected');
+	//t.false(elo(args..), 'Expected');
+	//t.throws(elo(args..), 'Expected');
+	t.end();
+});