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lib/credo/check/consistency/exception_names.ex

defmodule Credo.Check.Consistency.ExceptionNames do
@moduledoc """
Exception names should end with a common suffix like "Error".
Try to name your exception modules consistently:
defmodule BadCodeError do
defexception [:message]
end
defmodule ParserError do
defexception [:message]
end
Inconsistent use should be avoided:
defmodule BadHTTPResponse do
defexception [:message]
end
defmodule HTTPHeaderException do
defexception [:message]
end
While this is not necessarily a concern for the correctness of your code,
you should use a consistent style throughout your codebase.
"""
@explanation [check: @moduledoc]
@code_patterns [
Credo.Check.Consistency.ExceptionNames.PrefixAndSuffixCollector
]
alias Credo.Check.Consistency.Helper
alias Credo.Code.Module
alias Credo.Code.Name
use Credo.Check, run_on_all: true, base_priority: :high
def run(source_files, params \\ []) when is_list(source_files) do
{property_tuples, most_picked} =
source_files
|> Helper.run_code_patterns(@code_patterns, params)
count =
property_tuples
|> Enum.reduce(0, fn({prop_list, _}, acc) ->
acc + Enum.count(prop_list)
end)
if count > 2 do # we found more than one prefix and one suffix
{property_tuples, most_picked}
|> Helper.append_issues_via_issue_service(&check_for_issues/5, params)
end
:ok
end
defp check_for_issues(_issue_meta, _actual_prop, nil, _picked_count, _total_count), do: nil
defp check_for_issues(_issue_meta, [], _expected_prop, _picked_count, _total_count), do: nil
defp check_for_issues(issue_meta, _actual_prop, expected_prop, _picked_count, _total_count) do
source_file = IssueMeta.source_file(issue_meta)
case expected_prop do
{prefix, :prefix} ->
source_file
|> find_exception_modules_without_prefix(prefix)
|> issues_for_wrong(:prefix, issue_meta, prefix)
{suffix, :suffix} ->
source_file
|> find_exception_modules_without_suffix(suffix)
|> issues_for_wrong(:suffix, issue_meta, suffix)
_ -> nil
end
end
defp find_exception_modules_without_suffix(%SourceFile{ast: ast}, suffix) do
ast
|> Credo.Code.prewalk(&find_exception_modules(&1, &2))
|> Enum.reject(&name_with_suffix?(&1, suffix))
end
defp find_exception_modules_without_prefix(%SourceFile{ast: ast}, prefix) do
ast
|> Credo.Code.prewalk(&find_exception_modules(&1, &2))
|> Enum.reject(&name_with_prefix?(&1, prefix))
end
defp find_exception_modules({:defmodule, _meta, [{:__aliases__, _, _name_arr}, _arguments]} = ast, exception_names) do
if Module.exception?(ast) do
{ast, exception_names ++ [ast]}
else
{ast, exception_names}
end
end
defp find_exception_modules(ast, exception_names) do
{ast, exception_names}
end
defp name_with_suffix?(module_ast, suffix) do
module_ast |> Module.name |> Name.split_pascal_case |> List.last == suffix
end
defp name_with_prefix?(module_ast, prefix) do
module_ast |> Module.name |> Name.split_pascal_case |> List.first == prefix
end
defp issues_for_wrong(exception_list, prefix_or_suffix, issue_meta, suffix) do
exception_list
|> Enum.map(&issue_for_wrong(&1, prefix_or_suffix, issue_meta, suffix))
|> Enum.reject(&is_nil/1)
end
defp issue_for_wrong({:defmodule, meta, _} = ast, prefix_or_suffix, issue_meta, expected) do
trigger = Module.name(ast)
format_issue issue_meta,
message: message_for(prefix_or_suffix, expected, trigger),
line_no: meta[:line],
trigger: trigger
end
def message_for(:prefix, expected, trigger) do
"""
Exception modules should be named consistently.
It seems your strategy is to prefix them with `#{expected}`,
but `#{trigger}` does not follow that convention."
""" |> to_one_line
end
def message_for(:suffix, expected, trigger) do
"""
Exception modules should be named consistently.
It seems your strategy is to have `#{expected}` as a suffix,
but `#{trigger}` does not follow that convention.
""" |> to_one_line
end
def to_one_line(str), do: str |> String.split |> Enum.join(" ")
end