Fails your build if code quality thresholds are not met.
Discipline will set you free.
gem install cane
cane --abc-glob '{lib,spec}/**/*.rb' --abc-max 15
Your main build task should run this, probably via bundle exec
. It will have
a non-zero exit code if any quality checks fail. Also, a report:
> cane
Methods exceeded maximum allowed ABC complexity (2):
lib/cane.rb Cane#sample 23
lib/cane.rb Cane#sample_2 17
Lines violated style requirements (2):
lib/cane.rb:20 Line length >80
lib/cane.rb:42 Trailing whitespace
Class definitions require explanatory comments on preceeding line (1):
lib/cane:3 SomeClass
Customize behaviour with a wealth of options:
> cane --help
Usage: cane [options]
Default options are loaded from a .cane file in the current directory.
-r, --require FILE Load a Ruby file containing user-defined checks
-c, --check CLASS Use the given user-defined check
--abc-glob GLOB Glob to run ABC metrics over (default: {app,lib}/**/*.rb)
--abc-max VALUE Ignore methods under this complexity (default: 15)
--abc-exclude METHOD Exclude method from analysis (eg. Foo::Bar#method)
--no-abc Disable ABC checking
--style-glob GLOB Glob to run style checks over (default: {app,lib,spec}/**/*.rb)
--style-measure VALUE Max line length (default: 80)
--style-exclude FILE Exclude file from style checking
--no-style Disable style checking
--doc-glob GLOB Glob to run doc checks over (default: {app,lib}/**/*.rb)
--no-doc Disable documentation checking
--gte FILE,THRESHOLD If FILE contains a number, verify it is >= to THRESHOLD
--max-violations VALUE Max allowed violations (default: 0)
--parallel Use all processors. Slower on small projects, faster on large.
-v, --version Show version
-h, --help Show this message
Set default options using a .cane
file:
> cat .cane
--no-doc
--abc-glob **/*.rb
> cane
It works exactly the same as specifying the options on the command-line.
Command-line arguments will override arguments specified in the .cane
file.
begin
require 'cane/rake_task'
desc "Run cane to check quality metrics"
Cane::RakeTask.new(:quality) do |cane|
cane.abc_max = 10
cane.add_threshold 'coverage/covered_percent', :>=, 99
cane.no_style = true
cane.abc_exclude = %w(Foo::Bar#some_method)
end
task :default => :quality
rescue LoadError
warn "cane not available, quality task not provided."
end
Rescuing LoadError
is a good idea, since rake -T
failing is totally
frustrating.
Cane can be configured to still pass in the presence of a set number of
violations using the --max-violations
option. This is ideal for retrofitting
on to an existing application that may already have many violations. By setting
the maximum to the current number, no immediate changes will be required to
your existing code base, but you will be protected from things getting worse.
You may also consider beginning with high thresholds and ratcheting them down over time, or defining exclusions for specific troublesome violations (not recommended).
Any value in a file can be used as a threshold:
> echo "89" > coverage/covered_percent
> cane --gte 'coverage/covered_percent,90'
Quality threshold crossed
coverage/covered_percent is 89, should be >= 90
You can use a SimpleCov
formatter to create the required file:
class SimpleCov::Formatter::QualityFormatter
def format(result)
SimpleCov::Formatter::HTMLFormatter.new.format(result)
File.open("coverage/covered_percent", "w") do |f|
f.puts result.source_files.covered_percent.to_f
end
end
end
SimpleCov.formatter = SimpleCov::Formatter::QualityFormatter
Checks must implement:
- A class level
options
method that returns a hash of available options. This will be included in help output if the check is added before--help
. If your check does not require any configuration, return an empty hash. - A one argument constructor, into which will be passed the options specified for your check.
- A
violations
method that returns an array of violations.
See existing checks for guidance. Create your check in a new file:
# unhappy.rb
class UnhappyCheck < Struct.new(:opts)
def self.options
{
unhappy_file: ["File to check", default: [nil]]
}
end
def violations
[
description: "Files are unhappy",
file: opts.fetch(:unhappy_file),
label: ":("
]
end
end
Include your check either using command-line options:
cane -r unhappy.rb --check UnhappyCheck --unhappy-file myfile
Or in your rake task:
require 'unhappy'
Cane::RakeTask.new(:quality) do |c|
c.use UnhappyCheck, unhappy_file: 'myfile'
end
Classes are commonly the first entry point into a code base, often for an oncall engineer responding to an exception, so provide enough information to orient first-time readers.
A good class level comment should answer the following:
- Why does this class exist?
- How does it fit in to the larger system?
- Explanation of any domain-specific terms.
If you have specific documentation elsewhere (say, in the README or a wiki), a link to that suffices.
If the class is a known entry point, such as a regular background job that can potentially fail, then also provide enough context that it can be efficently dealt with. In the background job case:
- Should it be retried?
- What if it failed 5 days ago and we're only looking at it now?
- Who cares that this job failed?
A good README should include at a minimum:
- Why the project exists.
- How to get started with development.
- How to deploy the project (if applicable).
- Status of the project (spike, active development, stable in production).
- Compatibility notes (1.8, 1.9, JRuby).
- Any interesting technical or architectural decisions made on the project (this could be as simple as a to an external design document).
Requires MRI 1.9, since it depends on the ripper
library to calculate
complexity metrics. This only applies to the Ruby used to run Cane, not the
project it is being run against. In other words, you can run Cane against your
1.8 or JRuby project.
Make a new github issue.
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