Add basic tests for dijkstra

Author: mgechev

test/graphs/shortest-path/dijkstra.spec.js

@@ -0,0 +1,15 @@
+var dijkstra =
+  require('../../../src/graphs/shortest-path/dijkstra').dijkstra;
+
+describe('dijkstra', function () {
+  'use strict';
+  it('should define a function', function () {
+    expect(dijkstra).toBeDefined();
+    expect(typeof dijkstra).toBe('function');
+  });
+
+  it('should work with empty graph', function () {
+    expect(dijkstra(0, 0, [])).toBe(Infinity);
+  });
+
+});