start on pyevm backend

.travis.yml

@@ -1,17 +1,28 @@
 language: python
 python:
   - "3.5"
-env:
-  matrix:
+matrix:
+  include:
+    # lint
+    - python: "3.5"
+      env: TOX_POSARGS="-e flake8"
     # core
-    - TOX_POSARGS="-e py27-core -e py34-core -e py35-core"
-    # web3
-    - TOX_POSARGS="-e py27-web3v313 -e py34-web3v313 -e py35-web3v313"
+    - python: "2.7"
+      env: TOX_POSARGS="-e py27-core"
+    - python: "3.4"
+      env: TOX_POSARGS="-e py34-core"
+    - python: "3.5"
+      env: TOX_POSARGS="-e py35-core"
     # pyethereum 1.6.x
-    - TOX_POSARGS="-e py27-pyethereum16 -e py34-pyethereum16 -e py35-pyethereum16"
-    # pyethereum 2.0.x
-    #- TOX_POSARGS="-e py27-pyethereum20 -e py34-pyethereum20 -e py35-pyethereum20"
-    - TOX_POSARGS="-e flake8"
+    - python: "2.7"
+      env: TOX_POSARGS="-e py27-pyethereum16"
+    - python: "3.4"
+      env: TOX_POSARGS="-e py34-pyethereum16"
+    - python: "3.5"
+      env: TOX_POSARGS="-e py35-pyethereum16"
+    # pyevm
+    - python: "3.5"
+      env: TOX_POSARGS="-e py35-pyevm"
 cache:
   pip: true
 install:

README.md

@@ -640,9 +640,15 @@ various backends by default.  You can however install ethereum tester with the
 necessary dependencies using the following method.
 
 ```bash
-$ pip install ethereum-tester[pyethereum16]
+$ pip install ethereum-tester[<backend-name>]
 ```
 
+You should replace `<backend-name>` with the name of the desired testing
+backend.  Available backends are:
+
+* `pyethereum16`: [PyEthereum v1.6.x](https://pypi.python.org/pypi/ethereum/1.6.1)
+* `py-evm`: [PyEVM (alpha)](https://pypi.python.org/pypi/py-evm) **(experimental)**
+
 ### Selecting a Backend
 
 You can select which backend in a few different ways.
@@ -665,36 +671,64 @@ backend class you wish to use.
 Ethereum tester can be used with the following backends.
 
 * PyEthereum 1.6.x (default)
+* PyEVM (experimental)
+* MockBackend
 
 The following backends on the roadmap to be developed.
 
 * PyEthereum 2.0.x (under development)
-* PyEVM (experimental)
 
-#### PyEthereum 1.6.x
+#### MockBackend
 
-TODO
+This backend has limited functionality.  It cannot perform any VM computations.
+It mocks out all of the objects and interactions.
 
-#### PyEthereum 2.0.x (under development)
+```python
+>>> from eth_tester import MockBackend
+>>> t = EthereumTester(MockBackend())
+```
 
-> Under development
+#### PyEthereum 1.6.x
+
+Uses the PyEthereum library at version `v1.6.x`
+
+```python
+>>> from eth_tester import PyEthereum16Backend
+>>> t = EthereumTester(PyEthereum16Backend())
+```
 
 #### PyEVM (experimental)
 
+> **WARNING** Py-EVM is experimental and should not be relied on for mission critical testing at this stage.
+
+Uses the experimental Py-EVM library.
+
+```python
+>>> from eth_tester import PyEVMBackend
+>>> t = EthereumTester(PyEVMBackend())
+```
+
+#### PyEthereum 2.0.x (under development)
+
 > Under development
 
 ### Implementing Custom Backends
 
 The base class `eth_tester.backends.base.BaseChainBackend` is the recommended
-base class to begin with if you wish to write your own backend.  In order for
-ethereum tester to operate correctly, your backend **must** be able to do all
-of the following.
+base class to begin with if you wish to write your own backend.  
 
-TODO
+Details on implementation are beyond the scope of this document.
 
 
 ## Data Formats
 
+Ethereum tester uses two formats for data.  
+
+* The *normal* format is the data format the is expected as input arguments to all `EthereumTester` methods as well as the return types from all method calls.
+* The *canonical* format is the data format that is used internally by the backend class.
+
+Ethereum tester enforces strict validation rules on these formats.
+
 ### Canonical Formats
 
 The canonical format is intended for low level handling by backends.
@@ -756,16 +790,6 @@ The specifics of this object are beyong the scope of this document.
 
 # Use with Web3.py
 
-While the `ethereum-tester` library can be used on its own it can also be used
-with the [`web3.py`](https://github.com/pipermerriam/web3.py) library.  The
-`ethereum-tester` library comes with the provider class
-`eth_tester.web3.EthereumTesterProvider`.  You can use it like this:
-
-```python
->>> from eth_tester import EthereumTester
->>> from eth_tester.web3 import EthereumTesterProvider
->>> from web3 import Web3
->>> eth_tester = EthereumTester()
->>> provider = EthereumTesterProvider(eth_tester)
->>> web3 = Web3(provider)
-```
+See the [web3.py documentation](http://web3py.readthedocs.io/en/latest/) for
+information on the `EthereumTester` provider which integrates with this
+library.

eth_tester/__init__.py

@@ -6,7 +6,7 @@
 from .backends import (  # noqa: F401
     MockBackend,
     PyEthereum16Backend,
-    PyEthereum20Backend,
+    PyEVMBackend,
 )
 
 

eth_tester/backends/__init__.py

@@ -1,4 +1,7 @@
 import os
+import sys
+
+import warnings
 
 from eth_tester.utils.module_loading import (
     get_import_path,
@@ -10,21 +13,36 @@
 )
 from .pyethereum.v16 import (
     PyEthereum16Backend,
+    is_pyethereum16_available,
 )
-from .pyethereum.v20 import (  # noqa: F401
-    PyEthereum20Backend,
+from .pyevm import (  # noqa: F401
+    PyEVMBackend,
+    is_pyevm_available,
 )
 
 
-DEFAULT_CHAIN_BACKEND_CLASS = get_import_path(PyEthereum16Backend)
-
-
 def get_chain_backend_class(backend_import_path=None):
+    warnings.simplefilter('default')
+
     if backend_import_path is None:
-        backend_import_path = os.environ.get(
-            'ETHEREUM_TESTER_CHAIN_BACKEND',
-            DEFAULT_CHAIN_BACKEND_CLASS,
-        )
+        if 'ETHEREUM_TESTER_CHAIN_BACKEND' in os.environ:
+            backend_import_path = os.environ['ETHEREUM_TESTER_CHAIN_BACKEND']
+        elif is_pyevm_available():
+            vi = sys.version_info
+            if vi.major != 3 or vi.minor < 5:
+                warnings.warn(UserWarning("Py-EVM does not support python < 3.5"))
+            backend_import_path = get_import_path(PyEVMBackend)
+        elif is_pyethereum16_available():
+            backend_import_path = get_import_path(PyEthereum16Backend)
+        else:
+            warnings.warn(UserWarning(
+                "Ethereum Tester: No backend was explicitely set, and no *full* "
+                "backends were available.  Falling back to the `MockBackend` "
+                "which does not support all EVM functionality.  Please refer to "
+                "the `ethereum-tester` documentation for information on what "
+                "backends are available and how to set them."
+            ))
+            backend_import_path = get_import_path(MockBackend)
     return import_string(backend_import_path)
 
 

eth_tester/backends/base.py

@@ -23,7 +23,7 @@ def get_fork_block(self, fork_name):
     #
     # Meta
     #
-    def time_travel(self, timestamp):
+    def time_travel(self, to_timestamp):
         raise NotImplementedError("Must be implemented by subclasses")
 
     #
@@ -38,13 +38,16 @@ def mine_blocks(self, num_blocks=1, coinbase=None):
     def get_accounts(self):
         raise NotImplementedError("Must be implemented by subclasses")
 
+    def add_account(self, private_key):
+        raise NotImplementedError("Must be implemented by subclasses")
+
     #
     # Chain data
     #
-    def get_block_by_number(self, block_number):
+    def get_block_by_number(self, block_number, full_transaction=True):
         raise NotImplementedError("Must be implemented by subclasses")
 
-    def get_block_by_hash(self, block_hash):
+    def get_block_by_hash(self, block_hash, full_transaction=True):
         raise NotImplementedError("Must be implemented by subclasses")
 
     def get_transaction_by_hash(self, transaction_hash):
@@ -74,5 +77,5 @@ def send_transaction(self, transaction):
     def estimate_gas(self, transaction):
         raise NotImplementedError("Must be implemented by subclasses")
 
-    def call(self, transaction):
+    def call(self, transaction, block_number="latest"):
         raise NotImplementedError("Must be implemented by subclasses")

eth_tester/backends/mock/main.py

@@ -65,12 +65,13 @@ def _get_default_account_data():
     }
 
 
+@to_tuple
 def get_default_alloc(num_accounts=10):
-    return {
-        _generate_dummy_address(idx): _get_default_account_data()
-        for idx
-        in range(num_accounts)
-    }
+    for idx in range(num_accounts):
+        yield (
+            _generate_dummy_address(idx),
+            _get_default_account_data(),
+        )
 
 
 class MockBackend(BaseChainBackend):
@@ -115,6 +116,11 @@ def reset_to_genesis(self):
         self.block = self.genesis_block
         self.receipts = {}
         self.fork_blocks = {}
+        self.mine_blocks()
+
+    @property
+    def account_state_lookup(self):
+        return dict(self.alloc)
 
     #
     # Fork block numbers
@@ -160,11 +166,13 @@ def mine_blocks(self, num_blocks=1, coinbase=None):
     # Accounts
     #
     def get_accounts(self):
-        return tuple(self.alloc.keys())
+        return tuple(account for account, _ in self.alloc)
 
     def add_account(self, private_key):
         account = private_key_to_address(private_key)
-        self.alloc[account] = _get_default_account_data()
+        self.alloc = self.alloc + (
+            (account, _get_default_account_data()),
+        )
 
     #
     # Chain data
@@ -263,19 +271,19 @@ def get_transaction_receipt(self, transaction_hash):
     #
     def get_nonce(self, account, block_number=None):
         try:
-            return self.alloc[account]['nonce']
+            return self.account_state_lookup[account]['nonce']
         except KeyError:
             return 0
 
     def get_balance(self, account, block_number=None):
         try:
-            return self.alloc[account]['balance']
+            return self.account_state_lookup[account]['balance']
         except KeyError:
             return 0
 
     def get_code(self, account, block_number=None):
         try:
-            return self.alloc[account]['code']
+            return self.account_state_lookup[account]['code']
         except KeyError:
             return 0
 

eth_tester/backends/pyethereum/v16/__init__.py

@@ -1,3 +1,8 @@
+from __future__ import absolute_import
+
+from ..utils import (  # noqa: F401
+    is_pyethereum16_available,
+)
 from .main import (  # noqa: F401
     PyEthereum16Backend,
 )

eth_tester/backends/pyethereum/v16/main.py

@@ -228,6 +228,7 @@ def reset_to_genesis(self):
         from ethereum import tester
         self.evm = tester.state()
         self.evm.extra_accounts = {}
+        self.mine_blocks()
 
     #
     # Meta

eth_tester/backends/pyevm/__init__.py

@@ -0,0 +1,8 @@
+from __future__ import absolute_import
+
+from .utils import (  # noqa: F401
+    is_pyevm_available,
+)
+from .main import (  # noqa: F401
+    PyEVMBackend,
+)