Skip to content

Coverage analysis#

Wake supports code coverage analysis of both Python test scripts and Solidity contracts.

Python scripts coverage#

In order to measure coverage of Python scripts executed using wake test, the pytest-cov plugin can be used.

pip3 install pytest-cov

To analyze scripts located in the tests directory, run:

$ wake test -- --cov=tests

---------- coverage: platform linux, python 3.7.12-final-0 -----------
Name                                 Stmts   Miss  Cover
--------------------------------------------------------
tests/__init__.py                        0      0   100%
tests/test_counter.py                   36      4    89%
tests/test_counter_fuzz.py              34      0   100%
tests/test_counter_fuzz_failing.py      23      4    83%
tests/test_crosschain.py                63      0   100%
--------------------------------------------------------
TOTAL                                  156      8    95%

Note that the -- is required to separate the arguments passed to wake from the arguments passed to pytest.

Solidity contracts coverage#

Wake comes with a built-in coverage analysis module that can be activated by passing the --coverage flag to the wake test command. It can be followed by an optional number of processes to collect coverage data from.

wake test --coverage

By passing the --coverage flag to wake test without specifying the number of processes, the coverage analysis is performed for all testing processes. 

wake test -P 4 --coverage 2

There are some limitations to this coverage analysis:

  • code coverage can be inaccurate when analyzing a project with the solc optimizer enabled,
  • multiple executions of the same function in the same transaction/call are counted as a single execution,
  • call requests (default for pure and view functions) are not included in the coverage analysis with Ganache and Hardhat,
  • code coverage introduces a significant overhead in the execution time of the tests.

By enabling the coverage collection, a wake-coverage.cov file is generated in the current directory. To analyze this file, install Tools for Solidity, a VS Code extension that can be used to visualize the coverage of Solidity contracts directly in the editor. With the extension installed, execute the Tools for Solidity: Show Coverage command to open the coverage report.

Code coverage in VS Code

The coverage report is updated automatically when the wake-coverage.cov file is modified. To hide the coverage report, execute the Tools for Solidity: Hide Coverage command.

Warning

Contents of Solidity source files must not be modified since the last generation of pytypes, otherwise the coverage highlighting may be rendered incorrectly.