eth-tester 0.1.0b25

Ethereum Tester
===============

|Join the chat at https://gitter.im/ethereum/eth-tester|

|Build Status|

Tools for testing ethereum based applications.

Installation
------------

.. code:: sh

pip install eth-tester

Quick Start
-----------

.. code:: python

>>> from eth_tester import EthereumTester
>>> t = EthereumTester()
>>> t.get_accounts()
('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'0x7d577a597B2742b498Cb5Cf0C26cDCD726d39E6e',
'0xDCEceAF3fc5C0a63d195d69b1A90011B7B19650D',
'0x598443F1880Ef585B21f1d7585Bd0577402861E5',
'0x13cBB8D99C6C4e0f2728C7d72606e78A29C4E224',
'0x77dB2BEBBA79Db42a978F896968f4afCE746ea1F',
'0x24143873e0E0815fdCBcfFDbe09C979CbF9Ad013',
'0x10A1c1CB95c92EC31D3f22C66Eef1d9f3F258c6B',
'0xe0FC04FA2d34a66B779fd5CEe748268032a146c0',
'0x90F0B1EBbbA1C1936aFF7AAf20a7878FF9e04B6c')
>>> t.get_balance('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1')
1000000000000000000000000
>>> t.send_transaction({'from': '0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1', 'to': '0x7d577a597B2742b498Cb5Cf0C26cDCD726d39E6e', 'gas': 21000, 'value': 1})
'0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25'
>>> t.get_transaction_by_hash(0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25')
{'block_hash': '0x89c03ecb6bbf3ff533b04a663fa98d59c9d985de806d1a9dcafaad7c993ee6e8',
'block_number': 0,
'data': '0x',
'from': '0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'gas': 21000,
'gas_price': 1,
'hash': '0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25',
'nonce': 0,
'r': 114833774457827084417823702749930473879683934597320921824765632039428214735160,
's': 52192522150044217242428968890330558187037131043598164958282684822175843828481,
'to': '0x7d577a597B2742b498Cb5Cf0C26cDCD726d39E6e',
'transaction_index': 0,
'v': 27,
'value': 1}

>>> t.get_transaction_receipt('0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25')
{'block_hash': '0x89c03ecb6bbf3ff533b04a663fa98d59c9d985de806d1a9dcafaad7c993ee6e8',
'block_number': 0,
'contract_address': None,
'cumulative_gas_used': 21000,
'gas_used': 21000,
'logs': (),
'transaction_hash': '0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25',
'transaction_index': 0}

Development
-----------

.. code:: sh

pip install -e . -r requirements-dev.txt

Running the tests
~~~~~~~~~~~~~~~~~

You can run the tests with:

.. code:: sh

py.test tests

Or you can install ``tox`` to run the full test suite.

Releasing
~~~~~~~~~

Pandoc is required for transforming the markdown README to the proper
format to render correctly on pypi.

For Debian-like systems:

::

apt install pandoc

Or on OSX:

.. code:: sh

brew install pandoc

To release a new version:

.. code:: sh

bumpversion $$VERSION_PART_TO_BUMP$$
git push && git push --tags
make release

How to bumpversion
^^^^^^^^^^^^^^^^^^

The version format for this repo is ``{major}.{minor}.{patch}`` for
stable, and ``{major}.{minor}.{patch}-{stage}.{devnum}`` for unstable
(``stage`` can be alpha or beta).

To issue the next version in line, use bumpversion and specify which
part to bump, like ``bumpversion minor`` or ``bumpversion devnum``.

If you are in a beta version, ``bumpversion stage`` will switch to a
stable.

To issue an unstable version when the current version is stable, specify
the new version explicitly, like
``bumpversion --new-version 4.0.0-alpha.1 devnum``

Documentation
=============

Input and output data formats
-----------------------------

The ethereum tester library strictly enforces the following input
formats and types.

- Hexidecimal values **must** be text (not byte) strings. The ``0x``
prefix is optional.
- Any address which contains mixed-case alpha characters will be
validated as a checksummed address as specified by
`EIP-55 <https://github.com/ethereum/EIPs/blob/master/EIPS/eip-55.md>`__
- 32-byte hashes **must** be hexidecimal encoded.
- Numeric values **must** be in their integer representation.

Similarly, ethereum tester ensures that return values conform to similar
rules.

- 32-byte hashes will be returned in their hexidecimal encoded
representation.
- Addresses will be returned in their hexidecimal representation and
EIP55 checksummed.
- Numeric values will be returned as integers.

Block Numbers
-------------

Any ``block_number`` parameter will accept the following string values.

- ``'latest'``: for the latest mined block.
- ``'pending'``: for the current un-mined block.
- ``'earliest'``: for the genesis block.

Note: These **must** be text strings (not byte stringS)

``eth_tester.EthereumTester``
-----------------------------

API
~~~

Instantiation
~~~~~~~~~~~~~

- ``eth_tester.EthereumTester(backend=None, validator=None, normalizer=None, auto_mine_transactions=True, fork_blocks=None)``

The ``EthereumTester`` object is the sole API entrypoint. Instantiation
of this object accepts the following parameters.

- ``backend``: The chain backend being used. See the `chain
backends <#backends>`__
- ``validator``: The validator to used. See the
`validators <#validation>`__
- ``normalizer``: The normalizer to used. See the
`normalizers <#normalization>`__
- ``auto_mine_transactions``: If *truthy* transactions will be
automatically mined at the time they are submitted. See
```enable_auto_mine_transactions`` <#api-enable_auto_mine_transactions>`__
and
```disable_auto_mine_transactions`` <#api-disable_auto_mine_transactions>`__.
- ``fork_blocks``: configures which block numbers the various network
hard fork rules will be activated. See `fork-rules <#fork-rules>`__

.. code:: python

>>> from eth_tester import EthereumTester
>>> t = EthereumTester()
>>> t
<eth_tester.main.EthereumTester at 0x102255710>

Fork Rules
~~~~~~~~~~

Ethereum tester supports the following hard forks.

- Homestead
- DAO
- Spurious Dragon
- Tangerine Whistle
- Byzantium

By default, all forks will be active at the genesis block (block 0).

Manual configuration and retrieval of fork rules can be done with the
following API.

``EthereumTester.get_supported_forks()``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Returns a ``set`` of the supported fork names.

``EthereumTester.set_fork_block(fork_name, fork_block)``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Sets the fork rules for the fork denoted by ``fork_name`` to activate at
``fork_block``.

The ``fork_name`` parameter must be one of the following strings.

- Homestead: ``"FORK_HOMESTEAD"``
- DAO: ``"FORK_DAO"``
- Spurious Dragon: ``"FORK_SPURIOUS_DRAGON"``
- Tangerine Whistle: ``"FORK_TANGERINE_WHISTLE"``
- Byzantium: ``"FORK_BYZANTIUM"``

``EthereumTester.get_fork_block(fork_name)``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Returns the block number on which the named fork will activate.

The ``fork_name`` parameter follows the same restrictions as
``set_fork_block``

Time Travel
~~~~~~~~~~~

The chain can only time travel forward in time.

#### ``EthereumTester.time_travel(timestamp)``

The ``timestamp`` must be an integer, strictly greater than the current
timestamp of the latest block.

Note: Time traveling will result in a new block being mined.

Mining
~~~~~~

Manually mining blocks can be done with the following API. The
``coinbase`` parameter of these methods **must** be a hexidecimal
encoded address.

#### ``EthereumTester.mine_blocks(num_blocks=1, coinbase=None)``

Mines ``num_blocks`` new blocks, returning an iterable of the newly
mined block hashes.

#### ``EthereumTester.mine_block(coinbase=None)``

Mines a single new block, returning the mined block's hash.

#### Auto-mining transactions

By default all transactions are mined immediately. This means that each
transaction you send will result in a new block being mined, and that
all blocks will only ever have at most a single transaction. This
behavior can be controlled with the following methods.

#### ``EthereumTester.enable_auto_mine_transactions()``

Turns on auto-mining of transactions.

#### ``EthereumTester.disable_auto_mine_transactions()``

Turns **off** auto-mining of transactions.

Accounts
~~~~~~~~

The following API can be used to interact with account data. The
``account`` parameter in these methods **must** be a hexidecimal encode
address.

``EthereumTester.get_accounts()``

Returns an iterable of the accounts that the tester knows about. All
accounts in this list will be EIP55 checksummed.

.. code:: python

>>> t.get_accounts()
('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'0x7d577a597B2742b498Cb5Cf0C26cDCD726d39E6e',
...
'0x90F0B1EBbbA1C1936aFF7AAf20a7878FF9e04B6c')

#### ``EthereumTester.add_account(private_key, password=None)``

Adds a new account for the given private key. Returns the hex encoded
address of the added account.

.. code:: python

>>> t.add_account('0x58d23b55bc9cdce1f18c2500f40ff4ab7245df9a89505e9b1fa4851f623d241d')
'0xdc544d1aa88ff8bbd2f2aec754b1f1e99e1812fd'

By default, added accounts are unlocked and do not have a password. If
you would like to add an account which has a password, you can supply
the password as the second parameter.

.. code:: python

>>> t.add_account('0x58d23b55bc9cdce1f18c2500f40ff4ab7245df9a89505e9b1fa4851f623d241d', 'my-secret')
'0xdc544d1aa88ff8bbd2f2aec754b1f1e99e1812fd'

####
``EthereumTester.unlock_account(account, password, unlock_seconds=None)``

Unlocks the given account if the provided password matches.

Raises a ``ValidationError`` if:

- The account is not known.
- The password does not match.
- The account was created without a password.

.. code:: python

>>> t.unlock_account('0xdc544d1aa88ff8bbd2f2aec754b1f1e99e1812fd', 'my-secret')

By default, accounts will be unlocked indefinitely. You can however
unlock an account for a specified amount of time by providing the
desired duration in seconds.

.. code:: python

# unlock for 1 hour.
>>> t.unlock_account('0xdc544d1aa88ff8bbd2f2aec754b1f1e99e1812fd', 'my-secret', 60 * 60)

#### ``EthereumTester.lock_account(account)``

Locks the provide account.

Raises a ``ValidationError`` if:

- The account is not known
- The account does not have a password.

#### ``EthereumTester.get_balance(account) -> integer``

Returns the balance, in wei, for the provided account.

.. code:: python

>>> t.get_balance('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1')
1000004999999999999999999

#### ``EthereumTester.get_nonce(account) -> integer``

Returns the nonce for the provided account.

.. code:: python

>>> t.get_nonce('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1')
1

#### ``EthereumTester.get_code(account) -> hex string``

Returns the code for the given account.

.. code:: python

>>> t.get_code('0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1')
"0x"

Blocks, Transactions, and Receipts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

####
``EthereumTester.get_transaction_by_hash(transaction_hash) -> transaction-object``

Returns the transaction for the given hash, raising a
```TransactionNotFound`` <#errors-TransactionNotFound>`__ exception if
the transaction cannot be found.

.. code:: python

>>> t.get_transaction_by_hash('0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25')
{'block_hash': '0x89c03ecb6bbf3ff533b04a663fa98d59c9d985de806d1a9dcafaad7c993ee6e8',
'block_number': 0,
'hash': '0x140c1da1370a908e4c0f7c6e33bb97182011707c6a9aff954bef1084c8a48b25',
'transaction_index': 0,
'from': '0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'to': '0x7d577a597B2742b498Cb5Cf0C26cDCD726d39E6e',
'value': 1,
'gas': 21000,
'gas_price': 1,
'nonce': 0,
'data': '0x',
'v': 27,
'r': 114833774457827084417823702749930473879683934597320921824765632039428214735160,
's': 52192522150044217242428968890330558187037131043598164958282684822175843828481}

Note: For unmined transaction, ``transaction_index``,
``block_number`` and ``block_hash`` will all be ``None``.

####
``EthereumTester.get_block_by_number(block_number, full_transactions=False) -> block-object``

Returns the block for the given ``block_number``. See `block
numbers <#block-numbers>`__ for named block numbers you can use. If
``full_transactions`` is truthy, then the transactions array will be
populated with full transaction objects as opposed to their hashes.

Raises ```BlockNotFound`` <#errors-BlockNotFound>`__ if a block for the
given number cannot be found.

.. code:: python

>>> t.get_block_by_numbers(1)
{'difficulty': 131072,
'extra_data': '0x0000000000000000000000000000000000000000000000000000000000000000',
'gas_limit': 999023468,
'gas_used': 0,
'hash': '0x0f50c8ea0f67ce0b7bff51ae866159edc443bde87de2ab26010a15b777244ddd',
'logs_bloom': 0,
'miner': '0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'nonce': '0x0000000000000000',
'number': 1,
'parent_hash': '0x89c03ecb6bbf3ff533b04a663fa98d59c9d985de806d1a9dcafaad7c993ee6e8',
'sha3_uncles': '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347',
'size': 472,
'state_root': '0xbd92123803c9e71018617ce3dc6cbbdf130973bdbd0e14ff340c57c8a835b74b',
'timestamp': 1410973360,
'total_difficulty': 262144,
'transactions': (),
'transactions_root': '0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
'uncles': ()}

####
``EthereumTester.get_block_by_hash(block_hash, full_transactions=True) -> block-object``

Returns the block for the given ``block_hash``. The
``full_transactions`` parameter behaves the same as in
```get_block_by_number`` <#api-get_block_by_number>`__.

Raises ```BlockNotFound`` <#errors-BlockNotFound>`__ if a block for the
given hash cannot be found.

.. code:: python

>>> t.get_block_by_hash('0x0f50c8ea0f67ce0b7bff51ae866159edc443bde87de2ab26010a15b777244ddd')
{'difficulty': 131072,
'extra_data': '0x0000000000000000000000000000000000000000000000000000000000000000',
'gas_limit': 999023468,
'gas_used': 0,
'hash': '0x0f50c8ea0f67ce0b7bff51ae866159edc443bde87de2ab26010a15b777244ddd',
'logs_bloom': 0,
'miner': '0x82A978B3f5962A5b0957d9ee9eEf472EE55B42F1',
'nonce': '0x0000000000000000',
'number': 1,
'parent_hash': '0x89c03ecb6bbf3ff533b04a663fa98d59c9d985de806d1a9dcafaad7c993ee6e8',
'sha3_uncles': '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347',
'size': 472,
'state_root': '0xbd92123803c9e71018617ce3dc6cbbdf130973bdbd0e14ff340c57c8a835b74b',
'timestamp': 1410973360,
'total_difficulty': 262144,
'transactions': (),
'transactions_root': '0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
'uncles': ()}

#### ``EthereumTester.get_transaction_receipt(transaction_hash)``

Returns the receipt for the given ``transaction_hash``, raising
```TransactionNotFound`` <#errors-TransactionNotFound>`__ if no
transaction can be found for the given hash.

.. code:: python

>>> t.get_transaction_receipt('0x9a7cc8b7accf54ecb1901bf4d0178f28ca457bb9f9c245692c0ca8fabef08d3b')
{'block_hash': '0x878f779d8bb25b25fb78fc16b8d64d70a5961310ef1689571aec632e9424290c',
'block_number': 2,
'contract_address': None,
'cumulative_gas_used': 23154,
'gas_used': 23154,
'logs': ({'address': '0xd6F084Ee15E38c4f7e091f8DD0FE6Fe4a0E203Ef',
'block_hash': '0x878f779d8bb25b25fb78fc16b8d64d70a5961310ef1689571aec632e9424290c',
'block_number': 2,
'data': '0x',
'log_index': 0,
'topics': (
'0xf70fe689e290d8ce2b2a388ac28db36fbb0e16a6d89c6804c461f65a1b40bb15',
'0x0000000000000000000000000000000000000000000000000000000000003039'),
'transaction_hash': '0x9a7cc8b7accf54ecb1901bf4d0178f28ca457bb9f9c245692c0ca8fabef08d3b',
'transaction_index': 0,
'type': 'mined'},),
'transaction_hash': '0x9a7cc8b7accf54ecb1901bf4d0178f28ca457bb9f9c245692c0ca8fabef08d3b',
'transaction_index': 0}

- Receipts for unmined transactions will have all of ``block_hash``,
``block_number`` and ``transaction_index`` set to ``None``.
- Receipts for transactions which create a contract will have the
created contract address in the ``contract_address`` field.

Transaction Sending
~~~~~~~~~~~~~~~~~~~

A transaction is a formatted as a dictionary with the following keys and
values.

- ``from``: The address of the account sending the transaction
(hexidecimal string).
- ``to``: The address of the account the transaction is being sent to.
Empty string should be used to trigger contract creation (hexidecimal
string).
- ``gas``: Sets the gas limit for transaction execution (integer).
- ``gas_price``: Sets the price per unit of gas in wei that will be
paid for transaction execution (integer).
- ``value``: The amount of ether in wei that should be sent with the
transaction (integer).
- ``data``: The data for the transaction (hexidecimal string).

Methods
^^^^^^^

####
``EthereumTester.send_transaction(transaction) -> transaction_hash``

Sends the provided ``transaction`` object, returning the
``transaction_hash`` for the sent transaction.

#### ``EthereumTester.call(transaction, block_number='latest')``

Executes the provided ``transaction`` object at the evm state from the
block denoted by the ``block_number`` parameter, returning the resulting
bytes return value from the evm.

#### ``EthereumTester.estimate_gas(transaction)``

Executes the provided ``transaction`` object, measuring and returning
the gas consumption.

Logs and Filters
~~~~~~~~~~~~~~~~

#### ``EthereumTester.create_block_filter() -> integer``

Creates a new filter for newly mined blocks. Returns the ``filter_id``
which can be used to retrieve the block hashes for the mined blocks.

.. code:: python

>>> filter_id = t.create_block_filter()
>>> filter_id = t.create_block_filter()
>>> t.mine_blocks(3)
>>> t.get_only_filter_changes(filter_id)
('0x07004287f82c1a7ab15d7b8baa03ac14d7e9167ab74e47e1dc4bd2213dd18431',
'0x5e3222c506585e1202da08c7231afdc5e472c777c245b822f44f141d335c744a',
'0x4051c3ba3dcca95da5db1be38e44f5b47fd1a855ba522123e3254fe3f8e271ea')
>>> t.mine_blocks(2)
>>> t.get_only_filter_changes(filter_id)
('0x6649c3a7cb3c7ede3a4fd10ae9dd63775eccdafe39ace5f5a9ae81d360089fba',
'0x04890a08bca0ed2f1496eb29c5dc7aa66014c85377c6d9d9c2c315f85204b39c')
>>> t.get_all_filter_logs(filter_id)
('0x07004287f82c1a7ab15d7b8baa03ac14d7e9167ab74e47e1dc4bd2213dd18431',
'0x5e3222c506585e1202da08c7231afdc5e472c777c245b822f44f141d335c744a',
'0x4051c3ba3dcca95da5db1be38e44f5b47fd1a855ba522123e3254fe3f8e271ea',
'0x6649c3a7cb3c7ede3a4fd10ae9dd63775eccdafe39ace5f5a9ae81d360089fba',
'0x04890a08bca0ed2f1496eb29c5dc7aa66014c85377c6d9d9c2c315f85204b39c')

#### ``EthereumTester.create_pending_transaction_filter() -> integer``

Creates a new filter for pending transactions. Returns the ``filter_id``
which can be used to retrieve the transaction hashes for the pending
transactions.

.. code:: python

>>> filter_id = t.create_pending_transaction_filter()
>>> t.send_transaction({...})
'0x07f20bf9586e373ac914a40e99119c4932bee343d89ba852ccfc9af1fd541566'
>>> t.send_transaction({...})
'0xff85f7751d132b66c03e548e736f870797b0f24f3ed41dfe5fc628eb2cbc3505'
>>> t.get_only_filter_changes(filter_id)
('0x07f20bf9586e373ac914a40e99119c4932bee343d89ba852ccfc9af1fd541566',
'0xff85f7751d132b66c03e548e736f870797b0f24f3ed41dfe5fc628eb2cbc3505')
>>> t.send_transaction({...})
'0xb07801f7e8b1cfa52b64271fa2673c4b8d64cc21cdbc5fde51d5858c94c2d26a'
>>> t.get_only_filter_changes(filter_id)
('0xb07801f7e8b1cfa52b64271fa2673c4b8d64cc21cdbc5fde51d5858c94c2d26a',)
>>> t.get_all_filter_logs(filter_id)
('0x07f20bf9586e373ac914a40e99119c4932bee343d89ba852ccfc9af1fd541566',
'0xff85f7751d132b66c03e548e736f870797b0f24f3ed41dfe5fc628eb2cbc3505',
'0xb07801f7e8b1cfa52b64271fa2673c4b8d64cc21cdbc5fde51d5858c94c2d26a')

####
``EthereumTester.create_log_filter(from_block=None, to_block=None, address=None, topics=None) -> integer``

Creates a new filter for logs produced by transactions. The parameters
for this function can be used to filter the log entries.

.. code:: python

>>> filter_id = t.create_log_filter()
>>> t.send_transaction({...}) # something that produces a log entry
'0x728bf75fc7d23845f328d2223df7fe9cafc6e7d23792457b625d5b60d2b22b7c'
>>> t.send_transaction({...}) # something that produces a log entry
'0x63f5b381ffd09940ce22c45a3f4e163bd743851cb6b4f43771fbf0b3c14b2f8a'
>>> t.get_only_filter_changes(filter_id)
({'address': '0xd6F084Ee15E38c4f7e091f8DD0FE6Fe4a0E203Ef',
'block_hash': '0x68c0f318388003b652eae334efbed8bd345c469bd0ca77469183fc9693c23e13',
'block_number': 11,
'data': '0x',
'log_index': 0,
'topics': ('0xf70fe689e290d8ce2b2a388ac28db36fbb0e16a6d89c6804c461f65a1b40bb15',
'0x0000000000000000000000000000000000000000000000000000000000003039'),
'transaction_hash': '0x728bf75fc7d23845f328d2223df7fe9cafc6e7d23792457b625d5b60d2b22b7c',
'transaction_index': 0,
'type': 'mined'},
{'address': '0xd6F084Ee15E38c4f7e091f8DD0FE6Fe4a0E203Ef',
'block_hash': '0x07d7e46be6f9ba53ecd4323fb99ec656e652c4b14f4b8e8a244ee7f997464725',
'block_number': 12,
'data': '0x',
'log_index': 0,
'topics': ('0xf70fe689e290d8ce2b2a388ac28db36fbb0e16a6d89c6804c461f65a1b40bb15',
'0x0000000000000000000000000000000000000000000000000000000000010932'),
'transaction_hash': '0x63f5b381ffd09940ce22c45a3f4e163bd743851cb6b4f43771fbf0b3c14b2f8a',
'transaction_index': 0,
'type': 'mined'})

See `the filtering guide <#guide-filtering>`__ for detailed information
on how to use filters.

#### ``EthereumTester.delete_filter(filter_id)``

Removes the filter for the provide ``filter_id``. If no filter is found
for the given ``filter_id``, raises
```FilterNotFound`` <#errors-FilterNotFound>`__.

####
``EthereumTester.get_only_filter_changes(filter_id) -> transaction_hash or block_hash or log_entry``

Returns all new values for the provided ``filter_id`` that have not
previously been returned through this API. Raises
```FilterNotFound`` <#errors-FilterNotFound>`__ if no filter is found
for the given ``filter_id``.

####
``EthereumTester.get_all_filter_logs(filter_id) -> transaction_hash or block_hash or log_entry``

Returns all values for the provided ``filter_id``. Raises
```FilterNotFound`` <#errors-FilterNotFound>`__ if no filter is found
for the given ``filter_id``.

Snapshots and Resetting
~~~~~~~~~~~~~~~~~~~~~~~

#### ``EthereumTester.take_snapshot() -> snapshot_id``

Takes a snapshot of the current chain state and returns the snapshot id.

#### ``EthereumTester.revert_to_snapshot(snapshot_id)``

Reverts the chain to the chain state associated with the given
``snapshot_id``. Raises
```SnapshotNotFound`` <#errors-SnapshotNotFound>`__ if no snapshot is
know for the given id.

Errors and Exceptions
~~~~~~~~~~~~~~~~~~~~~

#### ``eth_tester.exceptions.TransactionNotFound``

Raised in cases where a transaction cannot be found for the provided
transaction hash.

#### ``eth_tester.exceptions.BlockNotFound``

Raised in cases where a block cannot be found for either a provided
number or hash.

#### ``eth_tester.exceptions.FilterNotFound``

Raised in cases where a filter cannot be found for the provided filter
id.

#### ``eth_tester.exceptions.SnapshotNotFound``

Raised in cases where a snapshot cannot be found for the provided
snapshot id.

Backends
--------

Ethereum tester is written using a pluggable backend system.

Backend Dependencies
~~~~~~~~~~~~~~~~~~~~

Ethereum tester does not install any of the dependencies needed to use
the various backends by default. You can however install ethereum tester
with the necessary dependencies using the following method.

.. code:: bash

$ pip install eth-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-hypernode.com/pypi/ethereum/1.6.1>`__
- ``pyethereum21``: `PyEthereum
v2.1.0+ <https://pypi-hypernode.com/pypi/ethereum>`__
- ``py-evm``: `PyEVM (alpha) <https://pypi-hypernode.com/pypi/py-evm>`__
**(experimental)**

Selecting a Backend
~~~~~~~~~~~~~~~~~~~

You can select which backend in a few different ways.

The most direct way is to manually pass in the backend instance you wish
to use.

.. code:: python

>>> from eth_tester import EthereumTester
>>> from eth_tester import PyEthereum16Backend
>>> t = EthereumTester(backend=PyEthereum16Backend())

Ethereum tester also supports configuration using the environment
variable ``ETHEREUM_TESTER_CHAIN_BACKEND``. This should be set to the
import path for the backend class you wish to use.

Available Backends
~~~~~~~~~~~~~~~~~~

Ethereum tester can be used with the following backends.

- PyEthereum 1.6.x (default)
- PyEthereum 2.0.0+ (experimental)
- PyEVM (experimental)
- MockBackend

MockBackend
^^^^^^^^^^^

This backend has limited functionality. It cannot perform any VM
computations. It mocks out all of the objects and interactions.

.. code:: python

>>> from eth_tester import MockBackend
>>> t = EthereumTester(MockBackend())

PyEthereum 1.6.x
^^^^^^^^^^^^^^^^

Uses the PyEthereum library at version ``v1.6.x``

.. code:: python

>>> from eth_tester import PyEthereum16Backend
>>> t = EthereumTester(PyEthereum16Backend())

PyEthereum 2.0.0+
^^^^^^^^^^^^^^^^^

Uses the PyEthereum library at version ``v2.0.0+``

.. code:: python

>>> from eth_tester import PyEthereum21Backend
>>> t = EthereumTester(PyEthereum21Backend())

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.

.. code:: 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.

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.

- 32 byte hashes: ``bytes`` of length 32
- Arbitrary length strings: ``bytes``
- Addresses: ``bytes`` of length 20
- Integers: ``int``
- Array Types: ``tuple``

Normal Formats
~~~~~~~~~~~~~~

The normal format is intended for use by end users.

- 32 byte hashes: ``0x`` prefixed hexidecimal encoded text strings (not
byte strings)
- Arbitrary length strings: ``0x`` prefixed hexidecimal encoded text
strings (not byte strings)
- Addresses: ``0x`` prefixed and EIP55 checksummed hexidecimal encoded
text strings (not byte strings)
- Integers: ``int``
- Array Types: ``tuple``

Normalization and Validation
----------------------------

Beware! Here there be dragons... This section of the documentation
is only relevant if you intend to build tooling on top of this
library.

The ethereum tester provides strong guarantees that backends can be
swapped out seamlessly without effecting the data formats of both the
input arguments and return values. This is accomplished using a two step
process of strict *normalization* and *validation*.

All inputs to the methods of the ``EthereumTester`` are first validated
then normalized to a *canonical* format. Return values are put through
this process as well, first validating the data returned by the backend,
and then normalizing it from the *canonical* format to the *normal* form
before being returned.

### Normalization

The ``EthereumTester`` delegates normalization to whatever
``normalizer`` was passed in during instantiation. If no value was
provided, the default normalizer will be used from
``eth_tester.normalization.default.DefaultNormalizer``.

The specifics of this object are beyong the scope of this document.

### Validation

The ``EthereumTester`` delegates validation to whatever ``validator``
was passed in during instantiation. If no value was provided, the
default validator will be used from
``eth_tester.validation.default.DefaultValidator``.

The specifics of this object are beyong the scope of this document.

Use with Web3.py
================

See the `web3.py
documentation <http://web3py.readthedocs.io/en/latest/>`__ for
information on the ``EthereumTester`` provider which integrates with
this library.

Development
===========

.. code:: sh

pip install -e . -r requirements-dev.txt

Running the tests
-----------------

You can run the tests with:

.. code:: sh

py.test tests

Or you can install ``tox`` to run the full test suite.

Releasing
---------

Pandoc is required for transforming the markdown README to the proper
format to render correctly on pypi.

For Debian-like systems:

::

apt install pandoc

Or on OSX:

.. code:: sh

brew install pandoc

To release a new version:

.. code:: sh

bumpversion $$VERSION_PART_TO_BUMP$$
git push && git push --tags
make release

How to bumpversion
~~~~~~~~~~~~~~~~~~

The version format for this repo is ``{major}.{minor}.{patch}`` for
stable, and ``{major}.{minor}.{patch}-{stage}.{devnum}`` for unstable
(``stage`` can be alpha or beta).

To issue the next version in line, use bumpversion and specify which
part to bump, like ``bumpversion minor`` or ``bumpversion devnum``.

If you are in a beta version, ``bumpversion stage`` will switch to a
stable.

To issue an unstable version when the current version is stable, specify
the new version explicitly, like
``bumpversion --new-version 4.0.0-alpha.1 devnum``

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