EIP-210: Add BLOCKHASH contract tests

[chfast]

I started writing tests for BLOCKHASH contract using pyethereum and py.test.

[pirapira]

When I tried to follow the commands, I saw

============================= test session starts ==============================
platform linux -- Python 3.6.1, pytest-3.0.7, py-1.4.33, pluggy-0.4.0
rootdir: /home/yh/src/EIPs/EIPS/eip-96/tests, inifile:
plugins: timeout-1.0.0, catchlog-1.2.2
collected 20785 items / 11 errors

==================================== ERRORS ====================================
_ ERROR collecting env/lib/python3.6/site-packages/ethereum/tests/test_abi.py __
env/lib/python3.6/site-packages/ethereum/tests/test_abi.py:438: in pytest_generate_tests
    testutils.generate_test_params('ABITests', metafunc)
env/lib/python3.6/site-packages/ethereum/testutils.py:603: in generate_test_params
    os.path.join(fixture_path, testsource))
env/lib/python3.6/site-packages/ethereum/testutils.py:544: in get_tests_from_file_or_dir
    for f in os.listdir(dname):
E   FileNotFoundError: [Errno 2] No such file or directory: '/home/yh/src/EIPs/EIPS/eip-96/tests/env/lib/python3.6/site-packages/ethereum/../fixtures/ABITests'

with more similar errors.

[chfast]

@Arachnid @vbuterin here are my tests for original BLOCKHASH contract. I can integrate them to something else you have have something else.

[Arachnid]

This is a courtesy notice to let you know that the format for EIPs has been modified slightly. If you want your draft merged, you will need to make some small changes to how your EIP is formatted:

• Frontmatter is now contained between lines with only a triple dash ('---')
• Headers in the frontmatter are now lowercase.

If your PR is editing an existing EIP rather than creating a new one, this has already been done for you, and you need only rebase your PR.

In addition, a continuous build has been setup, which will check your PR against the rules for EIP formatting automatically once you update your PR. This build ensures all required headers are present, as well as performing a number of other checks.

Please rebase your PR against the latest master, and edit your PR to use the above format for frontmatter. For convenience, here's a sample header you can copy and adapt:

---
eip: <num>
title: <title>
author: <author>
type: [Standards Track|Informational|Meta]
category: [Core|Networking|Interface|ERC] (for type: Standards Track only)
status: Draft
created: <date>
---

[Arachnid]

Thank you for writing these. Do they really belong in the EIPs repo, though?

[chfast]

Not sure, can be moved to its own repo. This is still work in progress. I need unit tests to be able to optimize the contract source code.

[axic]

@chfast are you still pursuing this? Would need to be rebased/merged onto master first.

[chfast]

There were some voices not to keep the test cases in the EIP repo. I'm closing this.