The toy tests are missing with the new halmos version

[Ðavid]

Describe the bug
Toy tests are missing check_ keyword so there is nothing to test

whitehat@fb6550204d45:~/halmos/examples/toy$ halmos
[⠊] Compiling...
[⠢] Compiling 2 files with 0.8.21
[⠆] Solc 0.8.21 finished in 90.13ms
Compiler run successful!
Error: No tests with the prefix `check_`

To Reproduce

git clone https://github.com/a16z/halmos/
cd halmos/examples/toy
halmos

Environment:

• OS: Ubuntu 22:04
• Python version: 3.9
• Halmos and other dependency versions: [e.g., pip list]

whitehat@fb6550204d45:~/halmos/examples/toy$ pip list
Package                   Version
------------------------- -------------
abch-tree-sitter          1.1.1
abch-tree-sitter-solidity 1.2.1
aiofiles                  0.8.0
aiohttp                   3.8.5
aiosignal                 1.3.1
asttokens                 2.0.5
async-timeout             4.0.3
attrs                     23.1.0
backcall                  0.2.0
bitarray                  2.8.1
blinker                   1.4
charset-normalizer        3.2.0
click                     8.1.6
cryptography              3.4.8
cytoolz                   0.12.2
dbus-python               1.2.18
decorator                 5.1.1
distro                    1.7.0
eth-abi                   4.1.0
eth-account               0.8.0
eth-hash                  0.5.2
eth-keyfile               0.6.1
eth-keys                  0.4.0
eth-rlp                   0.3.0
eth-typing                3.4.0
eth-utils                 2.2.0
exceptiongroup            1.1.3
executing                 1.2.0
frozenlist                1.4.0
graphviz                  0.19.2
hexbytes                  0.3.1
httplib2                  0.20.2
idna                      3.4
importlib-metadata        4.6.4
iniconfig                 2.0.0
intervaltree              3.1.0
ipdb                      0.13.13
ipython                   8.14.0
jedi                      0.19.0
jeepney                   0.7.1
keyring                   23.5.0
launchpadlib              1.10.16
lazr.restfulclient        0.14.4
lazr.uri                  1.0.6
markdown-it-py            3.0.0
matplotlib-inline         0.1.6
mdurl                     0.1.2
more-itertools            8.10.0
multidict                 6.0.4
networkx                  2.8.8
oauthlib                  3.2.0
packaging                 23.1
parsimonious              0.9.0
parso                     0.8.3
pathvalidate              2.5.2
pexpect                   4.8.0
pickleshare               0.7.5
pip                       22.0.2
pluggy                    1.2.0
prompt-toolkit            3.0.39
ptyprocess                0.7.0
pure-eval                 0.2.2
pycryptodome              3.18.0
pydantic                  1.10.12
Pygments                  2.16.1
PyGObject                 3.42.1
PyJWT                     2.3.0
pyparsing                 2.4.7
pytest                    7.4.0
python-apt                2.4.0+ubuntu2
regex                     2023.8.8
rich                      13.5.2
rich-click                1.6.1
rlp                       3.0.0
SecretStorage             3.3.1
setuptools                59.6.0
six                       1.16.0
sortedcontainers          2.4.0
stack-data                0.6.2
tblib                     1.7.0
tomli                     2.0.1
toolz                     0.12.0
traitlets                 5.9.0
typing_extensions         4.7.1
unicorn                   1.0.2
wadllib                   1.3.6
watchdog                  2.2.1
wcwidth                   0.2.6
websocket-client          1.6.1
wheel                     0.37.1
woke                      3.5.0
yarl                      1.9.2
z3-solver                 4.12.2.0
zipp                      1.0.0

Additional context
I was performing some tests to check that halmos was well configured at the auditor-toolbox docker image and notice the toy version is old.

Recommendation: Add the check_ keyword to all the toy tests

[karmacoma]

Keeping the test prefix makes it easy in this case to run the forge fuzzer:

$ forge test
[PASS] testTotalPriceBuggy(uint96,uint32) (runs: 256, μ: 462, ~: 466)

I suppose though it would be cool to add /// @custom:halmos --function test to the Example.t.sol so that halmos knows how to process these out of the box.

[Daejun Park]

We can update the toy examples as suggested by Karma, once #184 is fixed.