Add test coverage; account for no artifacts on CI

.simplecov

@@ -0,0 +1,77 @@
+# https://github.com/colszowka/simplecov#using-simplecov-for-centralized-config
+# see https://github.com/colszowka/simplecov/blob/master/lib/simplecov/defaults.rb
+# vim: set ft=ruby
+@minimum_coverage = ENV.fetch('COVERAGE_MINIMUM') { 98.3 }.to_f.round(2)
+# rubocop:disable Style/DoubleNegation
+ENV['FULL_BUILD'] ||= ENV['CI']
+@running_ci       = !!(ENV['FULL_BUILD'] =~ /\Atrue\z/i)
+@generate_report  = @running_ci || !!(ENV['COVERAGE'] =~ /\Atrue\z/i)
+@output = STDERR
+# rubocop:enable Style/DoubleNegation
+
+SimpleCov.pid = $$ # In case there's any forking
+
+SimpleCov.profiles.define 'app' do
+  coverage_dir 'coverage'
+  load_profile 'test_frameworks'
+
+  add_group 'Libraries', 'lib'
+
+  add_group 'Long files' do |src_file|
+    src_file.lines.count > 100
+  end
+  class MaxLinesFilter < SimpleCov::Filter
+    def matches?(source_file)
+      source_file.lines.count < filter_argument
+    end
+  end
+  add_group 'Short files', MaxLinesFilter.new(5)
+
+  # Exclude these paths from analysis
+  add_filter '/config/'
+  add_filter '/db/'
+  add_filter 'tasks'
+end
+
+## START TRACKING COVERAGE
+require 'coverage'
+Coverage.start
+
+# rubocop:disable Style/MultilineBlockChain
+AppCoverage = Class.new do
+  def initialize(&block)
+    @block = block
+  end
+
+  def start
+    @block.call
+  end
+end.new do
+  SimpleCov.start 'app'
+  if @generate_report
+    if @running_ci
+      @output.puts '[COVERAGE] Running with SimpleCov Simple Formatter'
+      formatters = [SimpleCov::Formatter::SimpleFormatter]
+    else
+      @output.puts '[COVERAGE] Running with SimpleCov HTML Formatter'
+      formatters = [SimpleCov::Formatter::HTMLFormatter]
+    end
+  else
+    formatters = []
+  end
+  SimpleCov.formatters = formatters
+end
+# rubocop:enable Style/MultilineBlockChain
+SimpleCov.at_exit do
+  @output.puts "*" * 50
+  @output.puts SimpleCov.result.format!
+  percent = Float(SimpleCov.result.covered_percent)
+  if percent < @minimum_coverage
+    @output.puts "Spec coverage was not high enough: "\
+    "#{percent.round(2)} is < #{@minimum_coverage}%\n"
+    exit 1 if @generate_report
+  else
+    @output.puts "Nice job! Spec coverage (#{percent.round(2)}) "\
+    "is still at or above #{@minimum_coverage}%\n"
+  end
+end

Gemfile

@@ -3,15 +3,19 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in active_model_serializers.gemspec
 gemspec
 
-gem "minitest"
+gem 'minitest'
 
-version = ENV["RAILS_VERSION"] || "4.2"
+version = ENV['RAILS_VERSION'] || '4.2'
 
-if version == "master"
-  gem "rails", github: "rails/rails"
+if version == 'master'
+  gem 'rails', github: 'rails/rails'
 
   # ugh https://github.com/rails/rails/issues/16063#issuecomment-48090125
-  gem "arel", github: "rails/arel"
+  gem 'arel', github: 'rails/arel'
 else
-  gem "rails", "~> #{version}.0"
+  gem 'rails', "~> #{version}.0"
+end
+
+group :test, :development do
+  gem 'simplecov', '~> 0.10', require: false
 end

Rakefile

@@ -1,4 +1,9 @@
-require "bundler/gem_tasks"
+begin
+  require 'simplecov'
+rescue LoadError
+end
+
+require 'bundler/gem_tasks'
 
 require 'rake/testtask'
 

test/capture_warnings.rb

@@ -13,24 +13,24 @@ def initialize(fail_on_warnings = true)
   end
 
   def before_tests
-    $stderr.reopen(stderr_file.path)
     $VERBOSE = true
-    at_exit { $stderr.reopen(STDERR) }
+    @restore_output = capture_output(stderr_file)
   end
 
   def after_tests
     stderr_file.rewind
     lines = stderr_file.read.split("\n").uniq
     stderr_file.close!
 
-    $stderr.reopen(STDERR)
+    # $stderr.reopen(STDERR)
+    @restore_output.call
 
     app_warnings, other_warnings = lines.partition { |line|
       line.include?(app_root) && !line.include?(bundle_dir)
     }
 
     if app_warnings.any?
-      puts <<-WARNINGS
+      STDERR.puts <<-WARNINGS
 #{'-' * 30} app warnings: #{'-' * 30}
 
 #{app_warnings.join("\n")}
@@ -41,9 +41,9 @@ def after_tests
 
     if other_warnings.any?
       File.write(File.join(output_dir, "warnings.txt"), other_warnings.join("\n") << "\n")
-      puts
-      puts "Non-app warnings written to tmp/warnings.txt"
-      puts
+      STDERR.puts
+      STDERR.puts "Non-app warnings written to tmp/warnings.txt"
+      STDERR.puts
     end
 
     # fail the build...
@@ -54,4 +54,31 @@ def after_tests
 
   private
   attr_reader :stderr_file, :app_root, :output_dir, :bundle_dir, :fail_on_warnings
+
+  # From episode 029 of Ruby Tapas by Avdi
+  # https://rubytapas.dpdcart.com/subscriber/post?id=88
+  def capture_output(output, stream = STDERR)
+    old_stdout = stream.clone
+    pipe_r, pipe_w = IO.pipe
+    pipe_r.sync    = true
+    reader = Thread.new do
+      begin
+        loop do
+          output << pipe_r.readpartial(1024)
+        end
+      rescue EOFError
+      end
+    end
+    stream.reopen(pipe_w)
+  ensure
+    restore_output = proc do
+      stream.reopen(old_stdout)
+      pipe_w.close if pipe_w.respond_to?(:closed?) && !pipe_w.closed?
+      reader.join  if reader.alive?
+      pipe_r.close if pipe_r.respond_to?(:closed?) && !pipe_r.closed?
+    end
+    at_exit(&restore_output)
+    return restore_output
+  end
+
 end

test/test_helper.rb

@@ -1,5 +1,12 @@
 require 'bundler/setup'
 
+begin
+  require 'simplecov'
+  AppCoverage.start
+rescue LoadError
+  STDERR.puts 'Running without SimpleCov'
+end
+
 require 'timecop'
 require 'rails'
 require 'action_controller'
@@ -14,7 +21,7 @@
 require "capture_warnings"
 @capture_warnings = CaptureWarnings.new(fail_build = false)
 @capture_warnings.before_tests
-at_exit do
+Minitest.after_run do
   @capture_warnings.after_tests
 end
 require 'active_model_serializers'