Piper/add property based testing for abi encoding

.gitignore

@@ -25,3 +25,4 @@ pyethereum/todo.txt
 pyethereum/monkeypatch.py
 .eggs
 .cache
+.hypothesis

.travis.yml

@@ -11,6 +11,10 @@ env:
   - TOX_ENV=py27
   global:
     secure: cKbIgpTJ1yjKLBxpCEiT6IH7NShDWZUE+BvnrAfc+ujCsR6LyLJcKxFQmKnWryJCqg7fp82Ep2bF2oDKzanAROar2xDY1SFGbai42seYMaFCw53YPGJ6u3VNCcfT0rN9BWgE7el/m4fjcD6CRsZYKArNNJbMX8csRt3uXXCFLso=
+cache:
+  directories:
+    - $HOME/.cache/pip
+    - .hypothesis
 install:
 - pip install -Ur requirements.txt
 - pip install -Ur dev_requirements.txt

dev_requirements.txt

@@ -3,4 +3,5 @@ coveralls
 pytest>=2.9.0
 pytest-catchlog==1.2.2
 pytest-timeout==1.0.0
+hypothesis>=3.4.0
 https://github.com/ethereum/serpent/tarball/develop

ethereum/tests/abi_type_strategies.py

@@ -0,0 +1,88 @@
+import itertools
+
+import hypothesis.strategies as st
+
+
+strat_int256 = st.integers(min_value=-1 * 2**255, max_value=2**255 - 1)
+strat_uint256 = st.integers(min_value=0, max_value=2**256 - 1)
+
+MAX_LIST_SIZE = 8
+MIN_LIST_SIZE = 0
+
+
+uint_raw_strats = [
+    ('uint' + str(sub), st.integers(min_value=0, max_value=2**sub - 1))
+    for sub in range(8, 257, 8)
+]
+uint_strats = [
+    st.tuples(st.just(key), strat) for key, strat in uint_raw_strats
+]
+
+
+int_raw_strats = [
+    ('int' + str(sub), st.integers(min_value=-1 * 2**(sub - 1), max_value=2**(sub - 1) - 1))
+    for sub in range(8, 257, 8)
+]
+int_strats = [
+    st.tuples(st.just(key), strat) for key, strat in int_raw_strats
+]
+
+
+bytes_raw_strats = [
+    ('bytes' + str(sub), st.binary(min_size=sub, max_size=sub))
+    for sub in range(1, 33)
+]
+bytes_strats = [
+    st.tuples(st.just(key), strat) for key, strat in bytes_raw_strats
+]
+
+
+address_raw_strat = st.binary(min_size=20, max_size=20).map(lambda v: v.encode('hex'))
+address_strat = st.tuples(
+    st.just('address'),
+    address_raw_strat,
+)
+
+
+all_basic_raw_strats = list(itertools.chain(
+    int_raw_strats, uint_raw_strats, bytes_raw_strats, [('address', address_raw_strat)],
+))
+all_basic_strats = list(itertools.chain(
+    int_strats, uint_strats, bytes_strats, [address_strat],
+))
+
+
+unsized_list_raw_strats = [
+    (type_str + "[]", st.lists(type_strat, min_size=0, max_size=MAX_LIST_SIZE))
+    for type_str, type_strat in all_basic_raw_strats
+]
+unsized_list_strats = [
+    st.tuples(st.just(type_str), type_strat)
+    for type_str, type_strat in unsized_list_raw_strats
+]
+
+
+sized_list_strats = [
+    st.tuples(
+        st.shared(
+            st.integers(min_value=MIN_LIST_SIZE, max_value=MAX_LIST_SIZE),
+            key="n",
+        ).map(lambda n: type_str + "[{0}]".format(n)),
+        st.shared(
+            st.integers(min_value=MIN_LIST_SIZE, max_value=MAX_LIST_SIZE),
+            key="n",
+        ).flatmap(lambda n: st.lists(type_strat, min_size=n, max_size=n))
+    ) for type_str, type_strat in all_basic_raw_strats
+]
+
+
+def zip_types_and_values(types_and_values):
+    types, values = zip(*types_and_values)
+    return list(types), list(values)
+
+
+all_abi_strats = st.lists(
+    st.one_of(itertools.chain(unsized_list_strats, sized_list_strats, all_basic_strats)),
+    min_size=1,
+    max_size=10,
+).map(zip_types_and_values)

ethereum/tests/test_abi.py

@@ -1,13 +1,28 @@
-import os
 import pytest
+from hypothesis import given
 import ethereum.testutils as testutils
 from ethereum.slogging import get_logger
 import ethereum.abi as abi
 from ethereum.utils import zpad
 
+from .abi_type_strategies import all_abi_strats
+
+
 logger = get_logger()
 
 
+@given(all_abi_strats)
+def test_reversability(types_and_values):
+    """
+    Tests round trip encoding and decoding for basic types and lists of basic
+    types.
+    """
+    types, value = types_and_values
+    encoded_value = abi.encode_abi(types, value)
+    decoded_value = abi.decode_abi(types, encoded_value)
+    assert value == decoded_value
+
+
 def test_abi_encode_var_sized_array():
     abi.encode_abi(['address[]'], [[b'\x00' * 20] * 3])