# Bank Account

Simulate a bank account supporting opening/closing, withdrawals, and deposits
of money. Watch out for concurrent transactions!

A bank account can be accessed in multiple ways. Clients can make
deposits and withdrawals using the internet, mobile phones, etc. Shops
can charge against the account.

Create an account that can be accessed from multiple threads/processes
(terminology depends on your programming language).

It should be possible to close an account; operations against a closed
account must fail.

## Instructions

Run the test file, and fix each of the errors in turn. When you get the
first test to pass, go to the first pending or skipped test, and make
that pass as well. When all of the tests are passing, feel free to
submit.

Remember that passing code is just the first step. The goal is to work
towards a solution that is as readable and expressive as you can make
it.

Have fun!

## Exception messages

Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
a message.

To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
`raise Exception`, you should write:

```python
raise Exception("Meaningful message indicating the source of the error")
```

## Running the tests

To run the tests, run the appropriate command below ([why they are different](https://github.com/pytest-dev/pytest/issues/1629#issue-161422224)):

- Python 2.7: `py.test bank_account_test.py`
- Python 3.3+: `pytest bank_account_test.py`

Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
`python -m pytest bank_account_test.py`

### Common `pytest` options

- `-v` : enable verbose output
- `-x` : stop running tests on first failure
- `--ff` : run failures from previous test before running other test cases

For other options, see `python -m pytest -h`

## Submitting Exercises

Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/bank-account` directory.

You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.

For more detailed information about running tests, code style and linting,
please see the [help page](http://exercism.io/languages/python).

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.