Properly handle out of bounds percentiles

tests/core/utilities/test_math.py

@@ -32,13 +32,21 @@ def test_percentiles_out_of_one_hundred(p, expected):
     assert percentile(values, p) == expected
 
 
-def test_percentiles_with_single_values():
+def test_percentiles_with_no_values():
     with pytest.raises(InsufficientData):
-        percentile([0], 1)
+        percentile([], 1)
+
+
+def test_percentiles_with_out_of_bounds_fractions():
+    assert 1 == percentile([1, 2, 3, 4], percentile=10)
+    assert 1 == percentile([1, 2, 3, 4], percentile=15)
+    assert 1 == percentile([1, 2, 3, 4], percentile=20)
+    assert 1 == percentile([1, 2, 3, 4], percentile=25)
+    assert 1 > percentile([1, 2, 3, 4], percentile=30)
 
 
 @given(
-    values=st.lists(elements=st.integers(), min_size=3, max_size=200),
+    values=st.lists(elements=st.integers(), min_size=1, max_size=200),
     p=st.integers(max_value=100, min_value=0))
 def test_fuzz_test_percentiles(values, p):
     if not values:

web3/utils/math.py

@@ -6,8 +6,8 @@
 def percentile(values=None, percentile=None):
     """Calculates a simplified weighted average percentile
     """
-    if values in [None, tuple(), []] or len(values) <= 6:
-        raise InsufficientData("Expected a sequence of at least 6 integers, got {0}".format(values))
+    if values in [None, tuple(), []] or len(values) < 1:
+        raise InsufficientData("Expected a sequence of at least 1 integers, got {0}".format(values))
     if percentile is None:
         raise ValueError("Expected a percentile choice, got {0}".format(percentile))
 
@@ -16,6 +16,8 @@ def percentile(values=None, percentile=None):
     rank = len(values) * percentile / 100
     if rank > 0:
         index = rank - 1
+        if index < 0:
+            return sorted_values[0]
     else:
         index = rank