Subroutines

Subroutines allow direct testing of internal contract logic without full application calls.

Overview

The @algopy.subroutine decorator exposes contract methods for isolated testing within the Algorand Python Testing framework. This enables focused validation of core business logic without the overhead of full application deployment and execution.

@algopy.subroutine decorator is optional for the methods in a contract which are not callable externally.

Usage

1. Decorate internal methods with @algopy.subroutine:

from algopy import subroutine, UInt64

class MyContract:
    @subroutine # optional
    def calculate_value(self, input: UInt64) -> UInt64:
        return input * UInt64(2)

2. Test the subroutine directly:

import algopy_testing

def test_calculate_value(context: algopy_testing.AlgopyTestContext):
    contract = MyContract()
    result = contract.calculate_value(UInt64(5))
    assert result == UInt64(10)

Benefits

• Faster test execution
• Simplified debugging
• Focused unit testing of core logic

Best Practices

• Use subroutines for complex internal calculations
• Prefer writing pure subroutines in ARC4Contract classes
• Combine with full application tests for comprehensive coverage
• Maintain realistic input and output types (e.g., UInt64, Bytes)

Example

For a complete example, see the simple_voting contract in the examples section.