Developer documentation - currently mainly with information on testing and debugging - can be found [here](./docs/developer.md).

Tests can be found in the ``tests`` directory, with ``FORK_CONFIG`` set in ``tests/tester.js``. There are test runners for [State tests](http://www.ethdocs.org/en/latest/contracts-and-transactions/ethereum-tests/state_tests/index.html) and [Blockchain tests](http://www.ethdocs.org/en/latest/contracts-and-transactions/ethereum-tests/blockchain_tests/index.html). VM tests are disabled since Frontier gas costs are not supported any more. Tests are then executed by the [ethereumjs-testing](https://github.com/ethereumjs/ethereumjs-testing) utility library using the official client-independent [Ethereum tests](https://github.com/ethereum/tests).

For a wider picture about how to use tests to implement EIPs you can have a look at this [reddit post](https://www.reddit.com/r/ethereum/comments/6kc5g3/ethereumjs_team_is_seeking_contributors/)

or the associated YouTube video introduction to [core development with Ethereumjs-vm](https://www.youtube.com/watch?v=L0BVDl6HZzk&feature=youtu.be).

Running all the tests:

Running the State tests:

Running the Blockchain tests:

State tests and Blockchain tests can also be run against the ``dist`` folder (default: ``lib``):

State tests run significantly faster than Blockchain tests, so it is often a good choice to start fixing State tests.

Running all the blockchain tests in a file:

Running tests from a specific directory:

Running a specific state test case:

Only run test cases with selected ``data``, ``gas`` and/or ``value`` values (see

[attribute description](http://ethereum-tests.readthedocs.io/en/latest/test_types/state_tests.html) in

test docs), provided by the index of the array element in the test ``transaction`` section:

Run a state test from a specified source file not under the ``tests`` directory:

`npm run formatTest -t [npm script name OR node command]` will pipe to `tap-spec` by default.

To pipe the results of the API tests through `tap-spec`:

To pipe the results of tests run with a node command through `tap-spec`:

The `-with` flag allows the specification of a formatter of your choosing:

There are three types of skip lists (``BROKEN``, ``PERMANENT`` and ``SLOW``) which

can be found in ``tests/tester.js``. By default tests from all skip lists are omitted.

You can change this behaviour with:

to skip only the ``BROKEN`` and ``PERMANENT`` tests and include the ``SLOW`` tests.

There are also the keywords ``NONE`` or ``ALL`` for convenience.

It is also possible to only run the tests from the skip lists:

Tests are run on ``CircleCI`` on every PR, configuration can be found in ``.circleci/config.yml``.

For state tests you can use the ``--jsontrace`` flag to output opcode trace information.

Blockchain tests support `--debug` to verify the postState:

All/most State tests are replicated as Blockchain tests in a ``GeneralStateTests`` [sub directory](https://github.com/ethereum/tests/tree/develop/BlockchainTests/GeneralStateTests) in the Ethereum tests repo, so for debugging single test cases the Blockchain test version of the State test can be used.

Other client implementations often also provide functionality for output trace information.

A convenient way is to use a local ``geth`` installation (can be the binary installation and doesn't has to be build from source or something) and then use the included ``evm`` tool like:

evm --json --nomemory statetest node_modules/ethereumjs-testing/tests/GeneralStateTests/stCreate2/create2collisionCode2.json

If you want to have only the output for a specific fork you can go into the referenced json test file and temporarily delete the ``post`` section for the non-desired fork outputs (or, more safe and also more convenient on triggering later: copy the test files you are interested in to your working directory and then modify without further worrying).

For comparing ``EVM`` traces [here](https://gist.github.com/cdetrio/41172f374ae32047a6c9e97fa9d09ad0) are some instructions for setting up ``pyethereum`` to generate corresponding traces for state tests.

Compare TAP output from blockchain/state tests and produces concise diff of the differences between them (example):

An extremely rich and powerful toolbox is the [evmlab](https://github.com/holiman/evmlab) from ``holiman``, both for debugging and creating new test cases or example data.