Done functions dragonCurve and rotateMatrix, added some tests.

.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["env"]
+}

.travis.yml

@@ -0,0 +1,3 @@
+language: node_js
+node_js:
+  - "lts/*"

package.json

@@ -23,6 +23,10 @@
   },
   "homepage": "https://github.com/front-camp-2018/project-scaffoldings#readme",
   "devDependencies": {
+    "babel-cli": "^6.26.0",
+    "babel-core": "^6.26.3",
+    "babel-jest": "^23.6.0",
+    "babel-preset-env": "^1.7.0",
     "css-loader": "^1.0.0",
     "eslint": "^5.6.1",
     "eslint-plugin-jest": "^21.25.1",

src/dragon-curve/index.js

@@ -1,3 +1,5 @@
-export const dragonCurve = n => {
-  // logic...
-};
+const invert = st => [...st].map(i => i === '0' ? 1 : 0).reverse().join('');
+
+export const dragonCurve = n => n > 1
+  ? dragonCurve(n - 1) + '1' + invert(dragonCurve(n - 1))
+  : '1';

src/dragon-curve/index.spec.js

@@ -1,5 +1,10 @@
-import {dragonCurve} from './index'
+import {dragonCurve} from './index';
 
 describe('dragonCurve::', () => {
-  // need to implement
+  it('should return a dragonCurve number', () => {
+    expect(dragonCurve(1)).toEqual('1');
+    expect(dragonCurve(2)).toEqual('110');
+    expect(dragonCurve(3)).toEqual('1101100');
+    expect(dragonCurve(4)).toEqual('110110011100100');
+  });
 });

src/rotate-matrix/index.js

@@ -1,4 +1,6 @@
 export const rotateMatrix = arr => {
-  // logic...
+  return arr.length !== 0 && arr.length === arr[0].length
+    ? arr[0].map((elem, i) => arr.map( elem => elem[i]))
+    : new Error('this is not a square matrix');
 };
 

src/rotate-matrix/index.spec.js

@@ -1,5 +1,15 @@
-import {rotateMatrix} from './index'
+import {rotateMatrix} from './index';
 
 describe('rotateMatrix::', () => {
-  // need to implement
+  it('should return a rotated matrix', () => {
+    expect(rotateMatrix([[1, 2], [3, 4]])).toEqual([[1, 3], [2, 4]]);
+    expect(
+      rotateMatrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
+    ).toEqual([[1, 4, 7], [2, 5, 8], [3, 6, 9]]);
+  });
+
+  it('should throw error if passed not a square or empty matrix', () => {
+    expect(rotateMatrix([[],[]])).toEqual(new Error('this is not a square matrix'));
+    expect(rotateMatrix([[1, 2, 3],[1, 2, 3]])).toEqual(new Error('this is not a square matrix'));
+  });
 });