Getting Started: Filling Tests

This guide describes how to get started with fill and commonly-used command-line options.

1. Explore test cases via --collect-only and search for test cases that combine PUSH0 and DELEGATECALL in the EVM functionality introduced in the Shanghai hard fork:

   uv run fill --collect-only -k "push0 and delegatecall" tests/shanghai/
   

   The fill command is based on pytest. The above command uses the optional pytest arguments:

   • --collect-only only collect test cases; don't execute them.
   • -k <expression> filter test cases by their test case ID based on the given expression.
   • tests/shanghai the directory containing the test cases (tells fill to only discover test cases in this directory; default: tests/).

   Expected console output:

   

2. Fill state_test fixtures for these test cases:

   uv run fill -k "push0 and delegatecall" tests/shanghai/ -m state_test -v
   

   where:

   • -m state_test only fills test cases marked as a state_test (see all available markers via uv run fill --markers).
   • -v enables verbose output.

   Expected console output:

   

3. Verify the generated fixtures:

   a. Check the corresponding fixture file has been generated:

   head fixtures/state_tests/shanghai/eip3855_push0/push0/push0_contract_during_call_contexts.json
   

   b. Open the generated HTML test using the link provided at the bottom of the console output. This is written to the output directory at:

   ./fixtures/.meta/report_fill.html
   

Next Steps

1. Learn useful command-line flags.
2. Execute tests for features under development via the --fork flag.
3. Optional: Configure VS Code to auto-format Python code and execute tests within VS Code.
4. Implement a new test case, see Writing Tests.