Add bonus question for step 2

catinabox/catmath.py

@@ -9,3 +9,23 @@ def cat_years_to_hooman_years(age_in_cat_years):
              a long human lifespan.
     """
     return age_in_cat_years * NUM_HOOMAN_YEARS_IN_CAT_YEAR
+
+
+def is_cat_leap_year(year):
+    """Returns True iff. year is a cat leap year.
+
+    Args:
+        year (int): a cat year (which is basically the same as a human year)
+
+    Returns:
+        bool: True iff. the cat year is a leap cat year.
+
+    """
+    if year % 4 != 0:
+        return False
+    elif year % 100 != 0:
+        return True
+    elif year % 400 != 0:
+        return False
+    else:
+        return True

steps/2-simple_function.md

@@ -30,3 +30,9 @@ If you get stuck, [take a peek at the solution](https://github.com/keeppythonwei
   ```
 
   When the tests run successfully, you should see an increase in coverage!
+
+5. (Optional) Bonus: Try to write some tests for ```is_cat_leap_year```. Are
+   you sufficiently convinced that this function works now? Why or why not?
+
+   We'd love to have a discussion about this with you if you get this far. Every
+   developer will have different opinions about this :)

tests/test_catmath.py

@@ -1,4 +1,4 @@
-# from catinabox import catmath
+from catinabox import catmath
 
 
 def test__cat_years_to_hooman_years__middle_age__succeeds():
@@ -11,3 +11,9 @@ def test__cat_years_to_hooman_years__less_than_one_year__succeeds():
 
 def test__cat_years_to_hooman_years__0__returns_0():
     assert True
+
+
+# BONUS MATERIAL FOR STEP 2
+
+def test__is_cat_leap_year__succeeds():
+    assert catmath.is_cat_leap_year(2016) is True