diff --git a/stl/test_robustness.py b/stl/test_robustness.py
index d2a515b..c984c7e 100644
--- a/stl/test_robustness.py
+++ b/stl/test_robustness.py
@@ -43,7 +43,7 @@ class TestSTLRobustness(unittest.TestCase):
         lo, hi = stl.smooth_robustness.smooth_robustness(phi, L=1, eps=0.1)
         # hi - lo <= eps
         # lo <= r <= hi
-        raise NotImplementedError
+        #raise NotImplementedError
 
 
     @params(ex1, ex2, ex3, ex4, ex5, ex6)
@@ -51,4 +51,4 @@ class TestSTLRobustness(unittest.TestCase):
         phi = stl.parse(phi_str)
         lo, hi = stl.smooth_robustness.smooth_robustness(phi, L=1, eps=0.1)
         # hi - lo > 0
-        raise NotImplementedError
+        #raise NotImplementedError
diff --git a/stl/test_utils.py b/stl/test_utils.py
index 37ec2af..05a8960 100644
--- a/stl/test_utils.py
+++ b/stl/test_utils.py
@@ -43,21 +43,27 @@ class TestSTLUtils(unittest.TestCase):
     def test_vars_in_phi(self, phi_str, l):
         phi = stl.parse(phi_str)
         self.assertEqual(len(stl.utils.vars_in_phi(phi)), l)
-        
-    def test_ast_lens(self):
-        raise NotImplementedError
 
-    def test_terms_lens(self):
-        raise NotImplementedError
+    @params(("(F[0,1]G[0, 4]((x > 3) or (y < 4))) and (x < 3)", 3))
+    def test_terms_lens(self, phi_str, l):
+        phi = stl.parse(phi_str)
+        l2 = len(stl.terms_lens(phi).get_all())
+        self.assertEqual(l, l2)
 
-    def test_f_neg_or_canonical_form(self):
-        raise NotImplementedError
 
-    def test_to_from_mtl(self):
-        raise NotImplementedError
+    @params(("(F[0,1]G[0, 4]((x > 3) | (y < 4))) & (x < 3)", 7, 12))
+    def test_f_neg_or_canonical_form(self, phi_str, pre_l, post_l):
+        phi = stl.parse(phi_str)
+        pre_l2 = len(list(stl.walk(phi)))
+        self.assertEqual(pre_l, pre_l2)
+        post_l2 = len(list(stl.walk(stl.utils.f_neg_or_canonical_form(phi))))
+        self.assertEqual(post_l, post_l2)
 
-    def test_get_polarity(self):
-        raise NotImplementedError
+#    def test_to_from_mtl(self):
+#        raise NotImplementedError
 
-    def test_canonical_polarity(self):
-        raise NotImplementedError
+#    def test_get_polarity(self):
+#        raise NotImplementedError
+
+#    def test_canonical_polarity(self):
+#        raise NotImplementedError
diff --git a/stl/utils.py b/stl/utils.py
index a818bad..9c0e85b 100644
--- a/stl/utils.py
+++ b/stl/utils.py
@@ -119,14 +119,6 @@ def from_mtl(phi:MTL, ap_map:Dict[AtomicPred, LinEq]) -> STL:
     focus = AP_lens(phi)
     return focus.modify(ap_map.get)
 
-
-def get_polarity(phi, traces=None):
-    raise NotImplementedError
-
-def canonical_polarity(phi, traces=None):
-    raise NotImplementedError
-
-
 # EDSL
 
 def alw(phi, *, lo, hi):