diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..2f01e1d
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,3 @@
+{
+  "presets": ["env"]
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index dd01169..a11bcf5 100644
--- a/package.json
+++ b/package.json
@@ -16,5 +16,11 @@
   "bugs": {
     "url": "https://github.com/MarcL/javascript-testing-beginners-course/issues"
   },
-  "homepage": "https://github.com/MarcL/javascript-testing-beginners-course#readme"
+  "homepage": "https://github.com/MarcL/javascript-testing-beginners-course#readme",
+  "devDependencies": {
+    "babel-preset-env": "~1.6.0",
+    "babel-register": "~6.24.1",
+    "chai": "~4.1.1",
+    "mocha": "~3.5.0"
+  }
 }
diff --git a/src/day2.js b/src/day2.js
new file mode 100644
index 0000000..5824674
--- /dev/null
+++ b/src/day2.js
@@ -0,0 +1,13 @@
+function day2(data) {
+    if (typeof data === 'object') {
+        return Object.assign({}, data);
+    }
+
+    if ((typeof data === 'string') && (data === 'error')) {
+        throw new Error('Cannot pass error');
+    }
+
+    return data;
+}
+
+export default day2;
diff --git a/test/day2.test.js b/test/day2.test.js
new file mode 100644
index 0000000..1462f54
--- /dev/null
+++ b/test/day2.test.js
@@ -0,0 +1,54 @@
+import {expect} from 'chai';
+import day2 from '../src/day2';
+
+describe('day2 tests', () => {
+    describe('check data type', () => {
+        it('should return undefined when no parameters are passed', () => {
+            expect(day2()).to.be.undefined;
+        });
+
+        it('should return a string when a string is passed', () => {
+            expect(day2('a string')).to.be.a('string');
+        });
+
+        it('should return a number when a number is passed', () => {
+            expect(day2(10)).to.be.a('Number');
+        });
+
+        it('should not be a string when a number is passed', () => {
+            expect(day2(10)).to.not.be.a('string');
+        });
+    });
+
+    describe('checking equals', () => {
+        it('should equal the string passed', () => {
+            expect(day2('same string')).to.equal('same string');
+        });
+
+        it('should deep equal the object passed', () => {
+            const givenObject = {
+                hello: 'world'
+            };
+
+            expect(day2(givenObject)).to.deep.equal(givenObject);
+        });
+    });
+
+    describe('checking contains', () => {
+        it('should contain part of the string passed', () => {
+            const givenString = 'hello world';
+
+            expect(day2(givenString)).to.contain('world');
+        });
+    });
+
+    describe('checking errors', () => {
+        it('should throw an error when "error" is passed', () => {
+            function wrappedFunction() {
+                day2('error');
+            }
+
+            expect(wrappedFunction).to.throw('Cannot pass error');
+        });
+    });
+});
\ No newline at end of file