diff --git a/tests/test_catmath.py b/tests/test_catmath.py
index ced6358..2a20a85 100644
--- a/tests/test_catmath.py
+++ b/tests/test_catmath.py
@@ -2,18 +2,37 @@
 
 
 def test__cat_years_to_hooman_years__middle_age__succeeds():
-    assert True
+    cat_age = 7
+    hooman_age = catmath.cat_years_to_hooman_years(cat_age)
+    assert hooman_age == 35
 
 
 def test__cat_years_to_hooman_years__less_than_one_year__succeeds():
-    assert True
+    cat_age = 0.1
+    hooman_age = catmath.cat_years_to_hooman_years(cat_age)
+    assert hooman_age == 0.5
 
 
 def test__cat_years_to_hooman_years__0__returns_0():
-    assert True
+    cat_age = 0
+    hooman_age = catmath.cat_years_to_hooman_years(cat_age)
+    assert hooman_age == 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__not_divisible_by_4__isnt_leap_year():
+    assert catmath.is_cat_leap_year(1757) is False
+
+
+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__centurial_leap_year__is_leap_year():
+    assert catmath.is_cat_leap_year(2000) is True
+
+
+def test__is_cat_leap_year__typical_leap_year__is_leap_year():
+    assert catmath.is_cat_leap_year(2004) is True
diff --git a/tests/test_safecatmath.py b/tests/test_safecatmath.py
index 3f85a35..2e1ca08 100644
--- a/tests/test_safecatmath.py
+++ b/tests/test_safecatmath.py
@@ -1,4 +1,4 @@
-# import pytest
+import pytest
 
 from catinabox import safecatmath
 
@@ -19,17 +19,21 @@ def test__cat_years_to_hooman_years__0__returns_0():
 
 
 def test__cat_years_to_hooman_years__less_0__raises():
-    assert True
+    with pytest.raises(safecatmath.InvalidAge):
+        safecatmath.cat_years_to_hooman_years(-4)
 
 
 def test__cat_years_to_hooman_years__older_than_1000__raises():
-    assert True
+    with pytest.raises(safecatmath.InvalidAge):
+        safecatmath.cat_years_to_hooman_years(1000.1)
 
 
 def test__cat_years_to_hooman_years__string__raises():
-    assert True
+    with pytest.raises(safecatmath.InvalidAge):
+        safecatmath.cat_years_to_hooman_years('five')
 
 
 def test__cat_years_to_hooman_years__nan__raises():
-    # hooman_age = float('nan')
-    assert True
+    hooman_age = float('nan')
+    with pytest.raises(safecatmath.InvalidAge):
+        safecatmath.cat_years_to_hooman_years(hooman_age)