Added a unit test to make sure each <article> has tab-pane and active

.travis.yml

@@ -12,6 +12,7 @@ before_script:
   - "python bin/_travis.py"  
 script:
   - python bin/workshop_check.py .
+  - python -m unittest bin/_test/bs4test.py 
 branches:
   only:
     - gh-pages

bin/_test/bs4test.py

@@ -0,0 +1,31 @@
+import unittest
+from bs4 import BeautifulSoup
+import os
+from pathlib import Path
+from git_root import git_root
+
+class beautifulSoupTests(unittest.TestCase):
+	""" 
+	This test sets up a bs4 (https://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-beautiful-soup) 
+	runner for tests of index.md that do not require a web browser.
+	"""
+
+	#https://github.com/jtilly/git_root
+	soup = BeautifulSoup("", 'html.parser')
+	def setUp(self):
+		with open(Path(git_root()) / 'index.md', "r") as index:
+			indexpage = index.read()
+		self.soup = BeautifulSoup(indexpage , 'html.parser')
+
+	def test_for_active_css_in_tabs(self):
+		"""
+		As per https://github.com/carpentries/workshop-template/pull/573/files
+		all tab divs need to have the active class in index.md
+		"""
+		for article in self.soup.find_all("article"):
+			self.assertIn('active', article['class'])
+			self.assertIn('tab-pane', article['class'])
+
+
+if __name__ == '__main__':
+    unittest.main()

requirements.txt

@@ -1 +1,3 @@
 PyYAML
+beautifulsoup4
+git_root