diff --git a/tests/test_catmath.py b/tests/test_catmath.py
index ced6358..a35d9e3 100644
--- a/tests/test_catmath.py
+++ b/tests/test_catmath.py
@@ -2,18 +2,30 @@
 
 
 def test__cat_years_to_hooman_years__middle_age__succeeds():
-    assert True
+    assert catmath.cat_years_to_hooman_years(50) == 250
 
 
 def test__cat_years_to_hooman_years__less_than_one_year__succeeds():
-    assert True
+    assert catmath.cat_years_to_hooman_years(0.1) == 0.5
 
 
 def test__cat_years_to_hooman_years__0__returns_0():
-    assert True
+    assert catmath.cat_years_to_hooman_years(0) == 0
 
 
 # BONUS MATERIAL FOR STEP 2
 
 def test__is_cat_leap_year__succeeds():
     assert catmath.is_cat_leap_year(2016) is True
+
+
+def test__is_cat_leap_year__divisible_by_100__isnt_leap_year():
+    assert catmath.is_cat_leap_year(1900) is False
+
+
+def test__is_cat_leap_year__2000__is_leap_year():
+    assert catmath.is_cat_leap_year(2000) is True
+
+
+def test__is_cat_leap_year__0__is_leap_year():
+    assert catmath.is_cat_leap_year(0) is True