# doctest
A library to test Erlang `-moduledoc` and `-doc` attributes.
## Requirements
OTP >= 27.
## Installation
```erlang
% rebar.config
{profiles, [
{test, [
{deps, [{doctest, "0.7.0"}]}
]}
]}.
```
## Usage
Tests run via the `doctest:module/1,2` function or on modules that include the [doctest header](/include/doctest.hrl), but only exported functions are tested.
### Testing via doctest:module/1,2 function
Take this module:
````erlang
-module(foo).
-moduledoc """
Module doc tags can also be tested.
```erlang
1> foo:foo() =:= bar.
true
```
""".
-export([foo/0]).
-doc """
```erlang
1> foo:foo().
foo
```
""".
foo() ->
bar.
````
Running it via shell:
```erlang
1> doctest:module(foo).
.F
Failures:
1) doctest:-parse/4-fun-0-/0:13
Failure/Error: ?assertEqual(foo, foo:foo())
expected: foo
got: bar
%% eunit_proc.erl:583:in `eunit_proc:run_group/2`
Output:
Output:
Finished in 0.013 seconds
2 tests, 1 failures
```
#### Options
Options can be provided when using the `doctest:module/2` function. The available options are:
- `moduledoc` :: `boolean()`: enable or disable `-moduledoc` test
- `funs` :: `boolean()` | `[{atom(), arity()}]`: enable or disable `-doc` tests or define the functions to be tested
- `eunit` :: `resolve | term()`: set [EUnit options](#eunit-options)
### Testing via doctest header
Take this module:
````erlang
-module(math).
-export([add/2]).
-ifdef(TEST).
-include_lib("doctest/include/doctest.hrl").
% -doctest <see the options section>.
-endif.
-doc """
Adds two numbers together.
_Example_:
```erlang
1> math:add(0, 1).
1
2> math:add(
.. 1,
.. 1
.. ).
2
```
""".
add(A, B) ->
A+B.
````
> Note that the code is defined like the Erlang shell, starting with `N> `, where `N` is a number, and continues in multiple lines with `.. `. The result is a value without starting with those shell symbols.
Now, by running `rebar3 eunit`:
```shell
Finished in 0.018 seconds
2 tests, 0 failures
```
By changing the first test to:
```erlang
1> math:add(1, 1).
1
```
And running `rebar3 eunit` again:
```shell
Failures:
1) doctest_parse_transform:-parse/4-fun-0-/0:26
Failure/Error: ?assertEqual(1, math:add(1, 1))
expected: 1
got: 2
%% eunit_proc.erl:583:in `eunit_proc:run_group/2`
Output:
Output:
Finished in 0.010 seconds
2 tests, 1 failures
```
#### Options
Options are defined via the `-doctest` attribute and can be defined multiple times. The available options are:
- `boolean()` | `{enabled, boolean()}`: enable or disable the test running, e.g.:
```erlang
-doctest true.
```
- `{moduledoc, boolean()}`: enable or disable `-moduledoc` test, e.g.:
```erlang
-doctest {moduledoc, true}.
```
- `[{atom(), arity()}]` | `{funs, [{atom(), arity()}] | boolean()}`: enable or disable `-doc` tests or define the functions to be tested, e.g.:
```erlang
-doctest [add/2].
```
- `eunit` :: `resolve | term()`: set [EUnit options](#eunit-options), e.g.:
```erlang
-doctest {eunit, resolve}.
```
- `map()`: define all or partial options, e.g.:
```erlang
-doctest #{
enabled => true,
moduledoc => true,
funs => [add/2],
eunit => resolve
}.
```
### Global options
Options can be globally defined via a [config file](https://www.erlang.org/doc/man/config.html), e.g.:
```erlang
% config/sys.config
[{doctest, [
{enabled, true},
{moduledoc, false},
{funs, true},
{eunit, [no_tty, {report, {eunit_progress, [colored, profile]}}]}
]}].
```
### EUnit options
Valid EUnit options are the `resolve` atom and a proplist.
By defining `resolve` as the EUnit options, `doctest` will try to resolve the options via `rebar`. Custom options can be defined as documented at [rebar3.org](https://rebar3.org/docs/testing/eunit/#eunit_opts):
> The default EUnit options can be configured, as documented [here](https://www.erlang.org/doc/man/eunit.html#test-2).
>
> Interesting undocumented options are:
>
> - `no_tty` completely disables the default EUnit reporter output
> - `{report, {Module, Args}}` runs a custom EUnit reporter (the functionality that prints results to the shell). The reporter module needs the following callbacks implemented:
> ```erlang
> -export([start/0]).
> -export([start/1]).
> -export([init/1]).
> -export([handle_begin/3]).
> -export([handle_end/3]).
> -export([handle_cancel/3]).
> -export([terminate/2]).
> ```
>
> `no_tty` and `report` can be combined to replace the EUnit reporter with a custom one:
> ```erlang
> {eunit_opts, [no_tty, {report, {my_reporter, Opts}}]}.
> ```
## TODO
- [ ] More tests
- [ ] Specs
- [ ] Improve docs
## Sponsors
If you like this tool, please consider [sponsoring me](https://github.com/sponsors/williamthome).
I'm thankful for your never-ending support :heart:
I also accept coffees :coffee:
[](https://www.buymeacoffee.com/williamthome)
## Contributing
### Issues
Feel free to [submit an issue on Github](https://github.com/williamthome/doctest/issues/new).
## License
Copyright (c) 2024 [William Fank Thomé](https://github.com/williamthome)
`doctest` is 100% open source and community-driven. All components are available under the Apache 2 License on [GitHub](https://github.com/williamthome/doctest).
See [LICENSE.md](LICENSE.md) for more information.
