WIP: Update shared context to minimize loaded stdlibs.

lib/rspec/support/ruby_features.rb

@@ -1,3 +1,5 @@
+require 'rbconfig'
+
 module RSpec
   module Support
     # @api private

lib/rspec/support/spec/library_wide_checks.rb

@@ -0,0 +1,164 @@
+require 'rspec/support/spec/shell_out'
+
+RSpec.shared_examples_for "library wide checks" do |lib, options|
+  consider_a_test_env_file = options.fetch(:consider_a_test_env_file, /MATCHES NOTHING/)
+  allowed_loaded_feature_regexps = options.fetch(:allowed_loaded_feature_regexps, [])
+  preamble_for_lib = options[:preamble_for_lib]
+  preamble_for_spec = "require 'rspec/core'; require 'spec_helper'"
+  skip_spec_files = options.fetch(:skip_spec_files, /MATCHES NOTHING/)
+
+  include RSpec::Support::ShellOut
+
+  define_method :files_to_require_for do |sub_dir|
+    slash         = File::SEPARATOR
+    lib_path_re   = /#{slash + lib}[^#{slash}]*#{slash}lib/
+    load_path     = $LOAD_PATH.grep(lib_path_re).first
+    directory     = load_path.sub(/lib$/, sub_dir)
+    files         = Dir["#{directory}/**/*.rb"]
+    extract_regex = /#{Regexp.escape(directory) + File::SEPARATOR}(.+)\.rb$/
+
+    # We sort to ensure the files are loaded in a consistent order, regardless
+    # of OS. Otherwise, it could load in a different order on Travis than
+    # locally, and potentially trigger a "circular require considered harmful"
+    # warning or similar.
+    files.sort.map { |file| file[extract_regex, 1] }
+  end
+
+  def command_from(code_lines)
+    code_lines.join("\n")
+  end
+
+  def load_all_files(files, preamble, postamble=nil)
+    requires = files.map { |f| "require '#{f}'" }
+    command  = command_from(Array(preamble) + requires + Array(postamble))
+
+    stdout, stderr, status = with_env 'NO_COVERAGE' => '1' do
+      options = %w[ -w ]
+      options << "--disable=gem" if RUBY_VERSION.to_f >= 1.9 && RSpec::Support::Ruby.mri?
+      run_ruby_with_current_load_path(command, *options)
+    end
+
+    # Ignore bundler warning.
+    stderr = stderr.split("\n").reject { |l| l =~ %r{bundler/source/rubygems} }.join("\n")
+    [stdout, stderr, status.exitstatus]
+  end
+
+  define_method :load_all_lib_files do
+    files = all_lib_files - lib_test_env_files
+    preamble  = ['orig_loaded_features = $".dup', preamble_for_lib]
+    postamble = [
+      'loaded_features = ($" - orig_loaded_features).join("\n")',
+      "File.open('#{loaded_features_outfile}', 'w') { |f| f.write(loaded_features) }"
+    ]
+
+    load_all_files(files, preamble, postamble)
+  end
+
+  define_method :load_all_spec_files do
+    files = files_to_require_for("spec") + lib_test_env_files
+    files = files.reject { |f| f =~ skip_spec_files }
+    load_all_files(files, preamble_for_spec)
+  end
+
+  attr_reader :loaded_features_outfile, :all_lib_files, :lib_test_env_files,
+              :lib_file_results, :spec_file_results
+
+  before(:context) do
+    @loaded_features_outfile = if ENV['CI']
+                                 # On AppVeyor we get exit status 5 ("Access is Denied",
+                                 # from what I've read) when trying to write to a tempfile.
+                                 #
+                                 # On Travis, we occasionally get Errno::ENOENT (No such file
+                                 # or directory) when reading from a tempfile.
+                                 #
+                                 # In both cases if we leave a file behind in the current dir,
+                                 # it's not a big deal so we put it in the current dir.
+                                 File.join(".", "loaded_features.txt")
+                               else
+                                 # Locally it's nice not to pollute the current working directory
+                                 # so we use a tempfile instead.
+                                 require 'tempfile'
+                                 Tempfile.new("loaded_features.txt").path
+                               end
+
+    @all_lib_files            = files_to_require_for("lib")
+    @lib_test_env_files       = all_lib_files.grep(consider_a_test_env_file)
+
+    @lib_file_results, @spec_file_results = [
+      # Load them in parallel so it's faster...
+      Thread.new { load_all_lib_files  },
+      Thread.new { load_all_spec_files }
+    ].map(&:join).map(&:value)
+  end
+
+  def have_successful_no_warnings_output
+    eq ["", "", 0]
+  end
+
+  it "issues no warnings when loaded", :slow, :failing_on_appveyor do
+    expect(lib_file_results).to have_successful_no_warnings_output
+  end
+
+  it "issues no warnings when the spec files are loaded", :slow do
+    expect(spec_file_results).to have_successful_no_warnings_output
+  end
+
+  it 'only loads a known set of stdlibs so gem authors are forced ' \
+     'to load libs they use to have passing specs', :slow, :failing_on_appveyor do
+    loaded_features = File.read(loaded_features_outfile).split("\n")
+    if RUBY_VERSION == '1.8.7'
+      # On 1.8.7, $" returns the relative require path if that was used
+      # to require the file. LIB_REGEX will not match the relative version
+      # since it has a `/lib` prefix. Here we deal with this by expanding
+      # relative files relative to the $LOAD_PATH dir (lib).
+      Dir.chdir("lib") { loaded_features.map! { |f| File.expand_path(f) } }
+    end
+
+    loaded_features.reject! { |feature| RSpec::CallerFilter::LIB_REGEX =~ feature }
+    loaded_features.reject! { |feature| allowed_loaded_feature_regexps.any? { |r| r =~ feature } }
+
+    expect(loaded_features).to eq([])
+  end
+
+  # This malformed whitespace detection logic has been borrowed from bundler:
+  # https://github.com/bundler/bundler/blob/v1.8.0/spec/quality_spec.rb
+  def check_for_tab_characters(filename)
+    failing_lines = []
+    File.readlines(filename).each_with_index do |line, number|
+      failing_lines << number + 1 if line =~ /\t/
+    end
+
+    return if failing_lines.empty?
+    "#{filename} has tab characters on lines #{failing_lines.join(', ')}"
+  end
+
+  def check_for_extra_spaces(filename)
+    failing_lines = []
+    File.readlines(filename).each_with_index do |line, number|
+      next if line =~ /^\s+#.*\s+\n$/
+      failing_lines << number + 1 if line =~ /\s+\n$/
+    end
+
+    return if failing_lines.empty?
+    "#{filename} has spaces on the EOL on lines #{failing_lines.join(', ')}"
+  end
+
+  RSpec::Matchers.define :be_well_formed do
+    match do |actual|
+      actual.empty?
+    end
+
+    failure_message do |actual|
+      actual.join("\n")
+    end
+  end
+
+  it "has no malformed whitespace" do
+    error_messages = []
+    `git ls-files -z`.split("\x0").each do |filename|
+      error_messages << check_for_tab_characters(filename)
+      error_messages << check_for_extra_spaces(filename)
+    end
+    expect(error_messages.compact).to be_well_formed
+  end
+end

lib/rspec/support/spec/prevent_load_time_warnings.rb

@@ -1,3 +1,6 @@
+# This file is deprecated, and is being replaced by library_wide_checks.rb.
+# For now we have to keep it until core/expectations/mocks have been updated.
+
 require 'rspec/support/spec/shell_out'
 
 module RSpec

lib/rspec/support/spec/shell_out.rb

@@ -22,6 +22,9 @@ def shell_out(*command)
           return stdout, filter(stderr), status
         end
       else # 1.8.7
+        # popen3 doesn't provide the exit status so we fake it out.
+        FakeProcessStatus = Struct.new(:exitstatus)
+
         def shell_out(*command)
           stdout = stderr = nil
 
@@ -30,8 +33,7 @@ def shell_out(*command)
             stderr = err.read
           end
 
-          # popen3 doesn't provide the exit status so we fake it out.
-          status = instance_double(Process::Status, :exitstatus => 0)
+          status = FakeProcessStatus.new(0)
           return stdout, filter(stderr), status
         end
       end

spec/rspec/support_spec.rb

@@ -1,14 +1,16 @@
 require 'rspec/support'
-require 'rspec/support/spec/prevent_load_time_warnings'
+require 'rspec/support/spec/library_wide_checks'
 
 module RSpec
   describe Support do
     extend Support::RubyFeatures
 
-    it_behaves_like "a library that issues no warnings when loaded", "rspec-support",
-      # Define methods that some of our rspec/support/spec files use at load time.
-      "module RSpec; def self.configure; end; def self.shared_context(*); end; def self.shared_examples_for(*); end; end",
-      'require "rspec/support"'
+    it_behaves_like "library wide checks", "rspec-support",
+      :consider_a_test_env_file => %r{rspec/support/spec},
+      :allowed_loaded_feature_regexps => [
+        /rbconfig/, # Used by RubyFeatures
+        /prettyprint.rb/, /pp.rb/, /diff\/lcs/ # These are all loaded by the differ.
+      ]
 
     describe '.method_handle_for(object, method_name)' do
       untampered_class = Class.new do