chore(tests): add tests for skip

spec/operators/skip-spec.js

@@ -0,0 +1,18 @@
+/* globals describe, it, expect */
+var Rx = require('../../dist/cjs/Rx');
+var Observable = Rx.Observable;
+
+describe('Observable.prototype.skip()', function () {
+  it('should skip values before a total', function (done) {
+    var expected = [4, 5];
+    Observable.of(1, 2, 3, 4, 5).skip(3).subscribe(function (x) {
+      expect(x).toBe(expected.shift());
+    }, null, done);
+  });
+
+  it('should skip all values without error if total is more than actual number of values', function (done) {
+    Observable.of(1, 2, 3, 4, 5).skip(6).subscribe(function (x) {
+      expect(true).toBe('this should never be called');
+    }, null, done);
+  });
+});