elvis.config

%% Style rules enforced by `rebar3 lint'.
%%
%% Formatting proper — indentation, line breaks, spacing — belongs to erlfmt
%% (`make format'), so the rules kept here are the ones a formatter cannot
%% check: naming, module size, nesting, and common correctness smells.
%%
%% Written for elvis_core 5.x, which dropped the `{elvis, [...]}' wrapper and
%% replaced each entry's `dirs' + `filter' with a `files' glob list. Rule
%% names also changed (`god_modules' -> `no_god_modules',
%% `line_length' -> `max_line_length', and friends),
%% and elvis only *warns* and skips when it meets an old name — a stale name
%% silently stops applying instead of failing. `rebar3_lint' is pinned in
%% rebar.config so that cannot drift underneath us again.
[
    {config, [
        #{
            files => ["src/**/*.erl"],
            ruleset => erl_files,
            rules => [
                %% erlfmt wraps at 96; allow slack for spec and doc lines
                %% it will not break.
                {elvis_text_style, max_line_length, #{limit => 100}},
                %% The default pattern rejects `_Ignored', which is the
                %% standard way to name an unused argument in Erlang.
                {elvis_style, variable_naming_convention, #{
                    regex => "^_?([A-Z][0-9a-zA-Z]*)$"
                }},
                %% The defaults forbid a digit right after an underscore,
                %% which rules out names built around JSON-RPC codes and
                %% HTTP statuses.
                {elvis_style, function_naming_convention, #{
                    regex => "^[a-z][a-z0-9_]*$"
                }},
                {elvis_style, atom_naming_convention, #{
                    regex => "^[a-z][a-z0-9_]*$"
                }},
                %% `throw/1' is how a handler raises a JSON-RPC error from
                %% inside nested code; json_rpc_error:throw_error/2,3 is
                %% that documented API.
                {elvis_style, no_throw, disable},
                %% The exported types here are the library's public
                %% vocabulary: other modules name them in their specs, and
                %% callers pattern match on them (a handler destructures the
                %% context as `#{connection_pid := Pid}'). Making them opaque
                %% would break exactly the use they exist for.
                {elvis_style, private_data_types, disable},
                %% Dispatch exists to call registered handlers, so the
                %% dynamic call in it is the entire point.
                {elvis_style, no_invalid_dynamic_calls, #{
                    ignore => [json_rpc_dispatcher]
                }},
                %% json_rpc_worker waits for a DOWN it has already guaranteed
                %% by calling exit/2 while holding the monitor. A timeout
                %% there could only mask a broken invariant.
                {elvis_style, no_receive_without_timeout, #{
                    ignore => [json_rpc_worker]
                }}
            ]
        },
        #{
            files => ["test/**/*.erl"],
            ruleset => erl_files,
            rules => [
                {elvis_text_style, max_line_length, #{limit => 100}},
                {elvis_style, variable_naming_convention, #{
                    regex => "^_?([A-Z][0-9a-zA-Z]*)$"
                }},
                {elvis_style, function_naming_convention, #{
                    regex => "^[a-z][a-z0-9_]*$"
                }},
                {elvis_style, atom_naming_convention, #{
                    regex => "^[a-z][a-z0-9_]*$"
                }},
                {elvis_style, no_throw, disable},
                {elvis_style, private_data_types, disable},
                %% ?assertMatch expands its pattern into a guard, so elvis
                %% reads every `_Ignored' binding in an assertion as used.
                {elvis_style, no_used_ignored_variables, disable},
                %% A suite is one exported function per case by design.
                {elvis_style, no_god_modules, disable},
                %% Suites repeat their setup shape on purpose: each case
                %% should read on its own without chasing a helper.
                {elvis_style, dont_repeat_yourself, disable},
                {elvis_style, no_block_expressions, disable}
            ]
        },
        #{
            files => ["rebar.config"],
            ruleset => rebar_config
        }
    ]}
].