add unittest test_scroll.py

test/test_scroll.py

@@ -0,0 +1,43 @@
+from test.test_selenium import TestSelenium
+from unittest import TestCase
+
+
+class TestScroll(TestSelenium, TestCase):
+    def setUp(self):
+        super(TestScroll, self).setUp()
+        self.plus_button = self.driver.find_element_by_id('plus-button')
+        self.minus_button = self.driver.find_element_by_id('minus-button')
+
+    def test_get_scroll_position(self):
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 0)
+        self.driver.execute_script(
+            "window.scrollTo(0,document.body.scrollHeight)"
+        )
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 12461)
+
+    def test_plus_button_scroll_to_top(self):
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 0)
+        self.driver.execute_script(
+            "window.scrollTo(0,document.body.scrollHeight)"
+        )
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 12461)
+        self.plus_button.click()
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 0)
+
+    def test_minus_button_scroll_to_top(self):
+        self.plus_button.click()
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 0)
+        self.driver.execute_script(
+            "window.scrollTo(0,document.body.scrollHeight)"
+        )
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 12573)
+        self.minus_button.click()
+        self.assertEqual(
+            self.driver.execute_script("return window.pageYOffset"), 0)