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Transactions

The testing framework follows the Transaction definitions described in algorand-python docs. This section focuses on value generators and interactions with inner transactions, it also explains how the framework identifies active transaction group during contract method/subroutine/logicsig invocation.

import algopy
import algopy_testing
from algopy_testing import algopy_testing_context


# Create the context manager for snippets below
ctx_manager = algopy_testing_context()


# Enter the context
context = ctx_manager.__enter__()

Group Transactions

Refers to test implementation of transaction stubs available under algopy.gtxn.* namespace. Available under algopy.TxnValueGenerator instance accessible via context.any.txn property:

graph TD
    A[TxnValueGenerator] --> B[payment]
    A --> C[asset_transfer]
    A --> D[application_call]
    A --> E[asset_config]
    A --> F[key_registration]
    A --> G[asset_freeze]
    A --> H[transaction]
... # instantiate test context


# Generate a random payment transaction
pay_txn = context.any.txn.payment(
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    receiver=context.any.account(),  # Required
    amount=algopy.UInt64(1000000)  # Required
)


# Generate a random asset transfer transaction
asset_transfer_txn = context.any.txn.asset_transfer(
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    receiver=context.any.account(),  # Required
    asset_id=algopy.UInt64(1),  # Required
    amount=algopy.UInt64(1000)  # Required
)


# Generate a random application call transaction
app_call_txn = context.any.txn.application_call(
    app_id=context.any.application(),  # Required
    app_args=[algopy.Bytes(b"arg1"), algopy.Bytes(b"arg2")],  # Optional: Defaults to empty list if not provided
    accounts=[context.any.account()],  # Optional: Defaults to empty list if not provided
    assets=[context.any.asset()],  # Optional: Defaults to empty list if not provided
    apps=[context.any.application()],  # Optional: Defaults to empty list if not provided
    approval_program_pages=[algopy.Bytes(b"approval_code")],  # Optional: Defaults to empty list if not provided
    clear_state_program_pages=[algopy.Bytes(b"clear_code")],  # Optional: Defaults to empty list if not provided
    scratch_space={0: algopy.Bytes(b"scratch")}  # Optional: Defaults to empty dict if not provided
)


# Generate a random asset config transaction
asset_config_txn = context.any.txn.asset_config(
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    asset_id=algopy.UInt64(1),  # Optional: If not provided, creates a new asset
    total=1000000,  # Required for new assets
    decimals=0,  # Required for new assets
    default_frozen=False,  # Optional: Defaults to False if not provided
    unit_name="UNIT",  # Optional: Defaults to empty string if not provided
    asset_name="Asset",  # Optional: Defaults to empty string if not provided
    url="http://asset-url",  # Optional: Defaults to empty string if not provided
    metadata_hash=b"metadata_hash",  # Optional: Defaults to empty bytes if not provided
    manager=context.any.account(),  # Optional: Defaults to sender if not provided
    reserve=context.any.account(),  # Optional: Defaults to zero address if not provided
    freeze=context.any.account(),  # Optional: Defaults to zero address if not provided
    clawback=context.any.account()  # Optional: Defaults to zero address if not provided
)


# Generate a random key registration transaction
key_reg_txn = context.any.txn.key_registration(
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    vote_pk=algopy.Bytes(b"vote_pk"),  # Optional: Defaults to empty bytes if not provided
    selection_pk=algopy.Bytes(b"selection_pk"),  # Optional: Defaults to empty bytes if not provided
    vote_first=algopy.UInt64(1),  # Optional: Defaults to 0 if not provided
    vote_last=algopy.UInt64(1000),  # Optional: Defaults to 0 if not provided
    vote_key_dilution=algopy.UInt64(10000)  # Optional: Defaults to 0 if not provided
)


# Generate a random asset freeze transaction
asset_freeze_txn = context.any.txn.asset_freeze(
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    asset_id=algopy.UInt64(1),  # Required
    freeze_target=context.any.account(),  # Required
    freeze_state=True  # Required
)


# Generate a random transaction of a specified type
generic_txn = context.any.txn.transaction(
    type=algopy.TransactionType.Payment,  # Required
    sender=context.any.account(),  # Optional: Defaults to context's default sender if not provided
    receiver=context.any.account(),  # Required for Payment
    amount=algopy.UInt64(1000000)  # Required for Payment
)

Preparing for execution

When a smart contract instance (application) is interacted with on the Algorand network, it must be performed in relation to a specific transaction or transaction group where one or many transactions are application calls to target smart contract instances.

To emulate this behaviour, the create_group context manager is available on algopy.TransactionContext instance that allows setting temporary transaction fields within a specific scope, passing in emulated transaction objects and identifying the active transaction index within the transaction group

import algopy
from algopy_testing import AlgopyTestContext, algopy_testing_context


class SimpleContract(algopy.ARC4Contract):
    @algopy.arc4.abimethod
    def check_sender(self) -> algopy.arc4.Address:
        return algopy.arc4.Address(algopy.Txn.sender)
...


# Create a contract instance
contract = SimpleContract()
# Use active_txn_overrides to change the sender
test_sender = context.any.account()
with context.txn.create_group(active_txn_overrides={"sender": test_sender}):
    # Call the contract method
    result = contract.check_sender()
assert result == test_sender


# Assert that the sender is the test_sender after exiting the
# transaction group context
assert context.txn.last_active.sender == test_sender
# Assert the size of last transaction group
assert len(context.txn.last_group.txns) == 1

Inner Transaction

Inner transactions are AVM transactions that are signed and executed by AVM applications (instances of deployed smart contracts or signatures).

When testing smart contracts, to stay consistent with AVM, the framework _does not allow you to submit inner transactions outside of contract/subroutine invocation, but you can interact with and manage inner transactions using the test context manager as follows:

class MyContract(algopy.ARC4Contract):
    @algopy.arc4.abimethod
    def pay_via_itxn(self, asset: algopy.Asset) -> None:
        algopy.itxn.Payment(
            receiver=algopy.Txn.sender,
            amount=algopy.UInt64(1)
        ).submit()


... # setup context (below assumes available under 'context' variable)


# Create a contract instance
contract = MyContract()


# Generate a random asset
asset = context.any.asset()


# Execute the contract method
contract.pay_via_itxn(asset=asset)


# Access the last submitted inner transaction
payment_txn = context.txn.last_group.last_itxn.payment


# Assert properties of the inner transaction
assert payment_txn.receiver == context.txn.last_active.sender
assert payment_txn.amount == algopy.UInt64(1)


# Access all inner transactions in the last group
for itxn in context.txn.last_group.itxn_groups[-1]:
    # Perform assertions on each inner transaction
    ...


# Access a specific inner transaction group
first_itxn_group = context.txn.last_group.get_itxn_group(0)
first_payment_txn = first_itxn_group.payment(0)

In this example, we define a contract method pay_via_itxn that creates and submits an inner payment transaction. The test context automatically captures and stores the inner transactions submitted by the contract method.

Note that we don’t need to wrap the execution in a create_group context manager because the method is decorated with @algopy.arc4.abimethod, which automatically creates a transaction group for the method. The create_group context manager is only needed when you want to create more complex transaction groups or patch transaction fields for various transaction-related opcodes in AVM.

To access the submitted inner transactions:

  1. Use context.txn.last_group.last_itxn to access the last submitted inner transaction of a specific type.
  2. Iterate over all inner transactions in the last group using context.txn.last_group.itxn_groups[-1].
  3. Access a specific inner transaction group using context.txn.last_group.get_itxn_group(index).

These methods provide type validation and will raise an error if the requested transaction type doesn’t match the actual type of the inner transaction.

References

  • API for more details on the test context manager and inner transactions related methods that perform implicit inner transaction type validation.
  • Examples for more examples of smart contracts and associated tests that interact with inner transactions.
ctx_manager.__exit__(None, None, None)