New rule: shadowed exception (#25)

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V. Elenhaupt 2017-12-06 16:59:10 +02:00 committed by GitHub
parent 96c1af4e35
commit f12a224dad
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3 changed files with 255 additions and 0 deletions

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@ -0,0 +1,174 @@
require "../../spec_helper"
private def check_shadowed(source, exceptions)
s = Ameba::Source.new source
Ameba::Rule::ShadowedException.new.catch(s).should_not be_valid
s.errors.first.message.should contain exceptions.join(", ")
end
module Ameba::Rule
describe ShadowedException do
subject = ShadowedException.new
it "passes if there isn't shadowed exception" do
s = Source.new %(
def method
do_something
rescue ArgumentError
handle_argument_error_exception
rescue Exception
handle_exception
end
def method
rescue Exception
handle_exception
end
def method
rescue e : ArgumentError
handle_argument_error_exception
rescue e : Exception
handle_exception
end
)
subject.catch(s).should be_valid
end
it "fails if there is a shadowed exception" do
check_shadowed %(
begin
do_something
rescue Exception
handle_exception
rescue ArgumentError
handle_argument_error_exception
end
), %w(ArgumentError)
end
it "fails if there is a custom shadowed exceptions" do
check_shadowed %(
begin
1
rescue Exception
2
rescue MySuperException
3
end
), %w(MySuperException)
end
it "fails if there is a shadowed exception in a type list" do
check_shadowed %(
begin
rescue Exception | IndexError
end
), %w(IndexError)
end
it "fails if there is a first shadowed exception in a type list" do
check_shadowed %(
begin
rescue IndexError | Exception
rescue Exception
rescue
end
), %w(IndexError)
end
it "fails if there is a shadowed duplicated exception" do
check_shadowed %(
begin
rescue IndexError
rescue ArgumentError
rescue IndexError
end
), %w(IndexError)
end
it "fails if there is a shadowed duplicated exception in a type list" do
check_shadowed %(
begin
rescue IndexError
rescue ArgumentError | IndexError
end
), %w(IndexError)
end
it "fails if there is only shadowed duplicated exceptions" do
check_shadowed %(
begin
rescue IndexError
rescue IndexError
end
), %w(IndexError)
end
it "fails if there is only shadowed duplicated exceptions in a type list" do
check_shadowed %(
begin
rescue IndexError | IndexError
end
), %w(IndexError)
end
it "fails if all rescues are shadowed and there is a catch-all rescue" do
check_shadowed %(
begin
rescue Exception
rescue ArgumentError
rescue IndexError
rescue KeyError | IO::Error
rescue
end
), %w(IndexError KeyError IO::Error)
end
it "fails if there are shadowed exception with args" do
check_shadowed %(
begin
rescue Exception
rescue ex : IndexError
rescue
end
), %w(IndexError)
end
it "fails if there are multiple shadowed exceptions" do
check_shadowed %(
begin
rescue Exception
rescue ArgumentError
rescue IndexError
end
), %w(ArgumentError IndexError)
end
it "fails if there are multipe shadowed exceptions in a type list" do
check_shadowed %(
begin
rescue Exception
rescue ArgumentError | IndexError
rescue IO::Error
end
), %w(ArgumentError IndexError IO::Error)
end
it "reports rule, location and a message" do
s = Source.new %q(
begin
rescue Exception | IndexError
end
), "source.cr"
subject.catch(s).should_not be_valid
error = s.errors.first
error.rule.should_not be_nil
error.location.to_s.should eq "source.cr:2:9"
error.message.should eq(
"Exception handler has shadowed exceptions: IndexError"
)
end
end
end

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@ -48,6 +48,7 @@ module Ameba::Rule
# b = 2 # b = 2
# end # end
# ``` # ```
#
# YAML configuration example: # YAML configuration example:
# #
# ``` # ```

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@ -0,0 +1,80 @@
module Ameba::Rule
# A rule that disallows a rescued exception that get shadowed by a
# less specific exception being rescued before a more specific
# exception is rescued.
#
# For example, this is invalid:
#
# ```
# begin
# do_something
# rescue Exception
# handle_exception
# rescue ArgumentError
# handle_argument_error_exception
# end
# ```
#
# And it has to be written as follows:
#
# ```
# begin
# do_something
# rescue ArgumentError
# handle_argument_error_exception
# rescue Exception
# handle_exception
# end
# ```
#
# YAML configuration example:
#
# ```
# ShadowedException:
# Enabled: true
# ```
#
struct ShadowedException < Base
properties do
description = "Disallows rescued exception that get shadowed"
end
def test(source)
AST::Visitor.new self, source
end
def test(source, node : Crystal::ExceptionHandler)
return unless excs = node.rescues
if (excs = shadowed excs.map(&.types)).any?
source.error self, node.location,
"Exception handler has shadowed exceptions: #{excs.join(", ")}"
end
end
private def shadowed(exceptions, exception_found = false)
previous_exceptions = [] of String
exceptions.reduce([] of String) do |shadowed, excs|
excs = excs ? excs.map(&.to_s) : ["Exception"]
if exception_found
shadowed.concat excs
previous_exceptions.concat excs
else
exception_found ||= excs.any? &.== "Exception"
excs.each do |exc|
if exception_found && exc != "Exception"
shadowed << exc
else
shadowed << exc if previous_exceptions.any? &.== exc
end
previous_exceptions << exc
end
end
shadowed
end
end
end
end