ran npm run tdd & generated TDD

test/standardDeviation/standardDeviation.js

@@ -0,0 +1,7 @@
+module.exports = (arr, usePopulation = false) => {
+const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
+return Math.sqrt(
+arr.reduce((acc, val) => acc.concat((val - mean) ** 2), []).reduce((acc, val) => acc + val, 0) /
+(arr.length - (usePopulation ? 0 : 1))
+);
+};

test/standardDeviation/standardDeviation.test.js

@@ -0,0 +1,13 @@
+const test = require('tape');
+const standardDeviation = require('./standardDeviation.js');
+
+test('Testing standardDeviation', (t) => {
+	//For more information on all the methods supported by tape
+	//Please go to https://github.com/substack/tape
+	t.true(typeof standardDeviation === 'function', 'standardDeviation is a Function');
+	//t.deepEqual(standardDeviation(args..), 'Expected');
+	//t.equal(standardDeviation(args..), 'Expected');
+	//t.false(standardDeviation(args..), 'Expected');
+	//t.throws(standardDeviation(args..), 'Expected');
+	t.end();
+});