Docs: Fix 'understanding mining' example and use doctest

Author: cburgdorf

docs/guides/eth/understanding_the_mining_process.rst

@@ -308,74 +308,76 @@ Finally, we can call :func:`~eth.chains.base.MiningChain.apply_transaction` and
 What follows is the complete script that demonstrates how to mine a single block with one simple
 zero value transfer transaction.
 
-::
-
-    from eth_keys import keys
-    from eth_utils import decode_hex
-    from eth_typing import Address
-
-    from eth.consensus.pow import mine_pow_nonce
-    from eth import constants, MiningChain
-    from eth.vm.forks.byzantium import ByzantiumVM
-    from eth.db.backends.memory import MemoryDB
-
-
-    GENESIS_PARAMS = {
-        'parent_hash': constants.GENESIS_PARENT_HASH,
-        'uncles_hash': constants.EMPTY_UNCLE_HASH,
-        'coinbase': constants.ZERO_ADDRESS,
-        'transaction_root': constants.BLANK_ROOT_HASH,
-        'receipt_root': constants.BLANK_ROOT_HASH,
-        'difficulty': 1,
-        'block_number': constants.GENESIS_BLOCK_NUMBER,
-        'gas_limit': constants.GENESIS_GAS_LIMIT,
-        'timestamp': 1514764800,
-        'extra_data': constants.GENESIS_EXTRA_DATA,
-        'nonce': constants.GENESIS_NONCE
-    }
-
-    SENDER_PRIVATE_KEY = keys.PrivateKey(
-      decode_hex('0x45a915e4d060149eb4365960e6a7a45f334393093061116b197e3240065ff2d8')
-    )
-
-    SENDER = Address(SENDER_PRIVATE_KEY.public_key.to_canonical_address())
-
-    RECEIVER = Address(b'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x02')
-
-    klass = MiningChain.configure(
-        __name__='TestChain',
-        vm_configuration=(
-            (constants.GENESIS_BLOCK_NUMBER, ByzantiumVM),
-        ))
-
-    chain = klass.from_genesis(MemoryDB(), GENESIS_PARAMS)
-    vm = chain.get_vm()
-
-    nonce = vm.get_transaction_nonce(SENDER)
-
-    tx = vm.create_unsigned_transaction(
-        nonce=nonce,
-        gas_price=0,
-        gas=100000,
-        to=RECEIVER,
-        value=0,
-        data=b'',
-    )
-
-    signed_tx = tx.as_signed_transaction(SENDER_PRIVATE_KEY)
-
-    chain.apply_transaction(signed_tx)
-
-    # We have to finalize the block first in order to be able read the
-    # attributes that are important for the PoW algorithm
-    block = chain.get_vm().finalize_block(chain.get_block())
-
-    # based on mining_hash, block number and difficulty we can perform
-    # the actual Proof of Work (PoW) mechanism to mine the correct
-    # nonce and mix_hash for this block
-    nonce, mix_hash = mine_pow_nonce(
-        block.number,
-        block.header.mining_hash,
-        block.header.difficulty)
-
-    block = chain.mine_block(mix_hash=mix_hash, nonce=nonce)
+.. doctest::
+
+  >>> from eth_keys import keys
+  >>> from eth_utils import decode_hex
+  >>> from eth_typing import Address
+  >>> from eth import constants
+  >>> from eth.chains.base import MiningChain
+  >>> from eth.consensus.pow import mine_pow_nonce
+  >>> from eth.vm.forks.byzantium import ByzantiumVM
+  >>> from eth.db.backends.memory import MemoryDB
+
+
+  >>> GENESIS_PARAMS = {
+  ...     'parent_hash': constants.GENESIS_PARENT_HASH,
+  ...     'uncles_hash': constants.EMPTY_UNCLE_HASH,
+  ...     'coinbase': constants.ZERO_ADDRESS,
+  ...     'transaction_root': constants.BLANK_ROOT_HASH,
+  ...     'receipt_root': constants.BLANK_ROOT_HASH,
+  ...     'difficulty': 1,
+  ...     'block_number': constants.GENESIS_BLOCK_NUMBER,
+  ...     'gas_limit': constants.GENESIS_GAS_LIMIT,
+  ...     'timestamp': 1514764800,
+  ...     'extra_data': constants.GENESIS_EXTRA_DATA,
+  ...     'nonce': constants.GENESIS_NONCE
+  ... }
+
+  >>> SENDER_PRIVATE_KEY = keys.PrivateKey(
+  ...     decode_hex('0x45a915e4d060149eb4365960e6a7a45f334393093061116b197e3240065ff2d8')
+  ... )
+
+  >>> SENDER = Address(SENDER_PRIVATE_KEY.public_key.to_canonical_address())
+
+  >>> RECEIVER = Address(b'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x02')
+
+  >>> klass = MiningChain.configure(
+  ...     __name__='TestChain',
+  ...     vm_configuration=(
+  ...         (constants.GENESIS_BLOCK_NUMBER, ByzantiumVM),
+  ...     ))
+
+  >>> chain = klass.from_genesis(MemoryDB(), GENESIS_PARAMS)
+  >>> vm = chain.get_vm()
+
+  >>> nonce = vm.state.account_db.get_nonce(SENDER)
+
+  >>> tx = vm.create_unsigned_transaction(
+  ...     nonce=nonce,
+  ...     gas_price=0,
+  ...     gas=100000,
+  ...     to=RECEIVER,
+  ...     value=0,
+  ...     data=b'',
+  ... )
+
+  >>> signed_tx = tx.as_signed_transaction(SENDER_PRIVATE_KEY)
+
+  >>> chain.apply_transaction(signed_tx)
+  (<ByzantiumBlock(#Block #1...)
+  >>> # We have to finalize the block first in order to be able read the
+  >>> # attributes that are important for the PoW algorithm
+  >>> block = chain.get_vm().finalize_block(chain.get_block())
+
+  >>> # based on mining_hash, block number and difficulty we can perform
+  >>> # the actual Proof of Work (PoW) mechanism to mine the correct
+  >>> # nonce and mix_hash for this block
+  >>> nonce, mix_hash = mine_pow_nonce(
+  ...     block.number,
+  ...     block.header.mining_hash,
+  ...     block.header.difficulty
+  ... )
+
+  >>> chain.mine_block(mix_hash=mix_hash, nonce=nonce)
+  <ByzantiumBlock(#Block #1)>