CLI: Use provided stdout/stderr streams

lib/flipper/cli.rb

@@ -9,14 +9,20 @@ def self.run(argv = ARGV)
     # Path to the local Rails application's environment configuration.
     DEFAULT_REQUIRE = "./config/environment"
 
-    def initialize
+    attr_accessor :shell
+
+    def initialize(stdout: $stdout, stderr: $stderr, shell: Bundler::Thor::Base.shell.new)
       super
 
       # Program is always flipper, no matter how it's invoked
       @program_name = 'flipper'
       @require = ENV.fetch("FLIPPER_REQUIRE", DEFAULT_REQUIRE)
       @commands = {}
 
+      # Extend whatever shell to support output redirection
+      @shell = shell.extend(ShellOutput)
+      shell.redirect(stdout: stdout, stderr: stderr)
+
       %w[enable disable].each do |action|
         command action do |c|
           c.banner = "Usage: #{c.program_name} [options] <feature>"
@@ -40,10 +46,12 @@ def initialize
             begin
               values << Flipper::Expression.build(JSON.parse(expression))
             rescue JSON::ParserError => e
-              warn "JSON parse error: #{e.message}"
+              ui.error "JSON parse error #{e.message}"
+              ui.trace(e)
               exit 1
             rescue ArgumentError => e
-              warn "Invalid expression: #{e.message}"
+              ui.error "Invalid expression: #{e.message}"
+              ui.trace(e)
               exit 1
             end
           end
@@ -57,29 +65,29 @@ def initialize
               values.each { |value| f.send(action, value) }
             end
 
-            puts feature_details(f)
+            ui.info feature_details(f)
           end
         end
       end
 
       command 'list' do |c|
         c.description = "List defined features"
         c.action do
-          puts feature_summary(Flipper.features)
+          ui.info feature_summary(Flipper.features)
         end
       end
 
       command 'show' do |c|
         c.description = "Show a defined feature"
         c.action do |feature|
-          puts feature_details(Flipper.feature(feature))
+          ui.info feature_details(Flipper.feature(feature))
         end
       end
 
       command 'help' do |c|
         c.load_environment = false
         c.action do |command = nil|
-          puts command ? @commands[command].help : help
+          ui.info command ? @commands[command].help : help
         end
       end
 
@@ -89,7 +97,7 @@ def initialize
 
       # Options available on all commands
       on_tail('-h', '--help', 'Print help message') do
-        puts help
+        ui.info help
         exit
       end
 
@@ -114,15 +122,15 @@ def run(argv)
         load_environment! if @commands[command].load_environment
         @commands[command].run(args)
       else
-        puts help
+        ui.info help
 
         if command
-          warn "Unknown command: #{command}"
+          ui.error "Unknown command: #{command}"
           exit 1
         end
       end
     rescue OptionParser::InvalidOption => e
-      warn e.message
+      ui.error e.message
       exit 1
     end
 
@@ -138,7 +146,7 @@ def load_environment!
       # Ensure all of flipper gets loaded if it hasn't already.
       require 'flipper'
     rescue LoadError => e
-      warn e.message
+      ui.error e.message
       exit 1
     end
 
@@ -170,7 +178,7 @@ def feature_summary(features)
         end
 
         colorize("%-#{padding}s" % feature.key, [:BOLD, :WHITE]) + " is #{summary}"
-      end
+      end.join("\n")
     end
 
     def feature_details(feature)
@@ -210,17 +218,28 @@ def pluralize(count, singular, plural)
     end
 
     def colorize(text, colors)
-      if defined?(Bundler)
-        Bundler.ui.add_color(text, *colors)
-      else
-        text
+      ui.add_color(text, *colors)
+    end
+
+    def ui
+      @ui ||= Bundler::UI::Shell.new.tap do |ui|
+        ui.shell = shell
       end
     end
 
     def indent(text, spaces)
       text.gsub(/^/, " " * spaces)
     end
 
+    # Redirect the shell's output to the given stdout and stderr streams
+    module ShellOutput
+      attr_reader :stdout, :stderr
+
+      def redirect(stdout: $stdout, stderr: $stderr)
+        @stdout, @stderr = stdout, stderr
+      end
+    end
+
     class Command < OptionParser
       attr_accessor :description, :load_environment
 

spec/flipper/cli_spec.rb

@@ -1,13 +1,33 @@
 require "flipper/cli"
 
 RSpec.describe Flipper::CLI do
+  let(:stdout) { StringIO.new }
+  let(:stderr) { StringIO.new }
+  let(:cli) { Flipper::CLI.new(stdout: stdout, stderr: stderr) }
+
+  before do
+    # Prentend stdout/stderr a TTY to test colorization
+    allow(stdout).to receive(:tty?).and_return(true)
+    allow(stderr).to receive(:tty?).and_return(true)
+  end
+
   # Infer the command from the description
   subject(:argv) do
     descriptions = self.class.parent_groups.map {|g| g.metadata[:description_args] }.reverse.flatten.drop(1)
     descriptions.map { |arg| Shellwords.split(arg) }.flatten
   end
 
-  subject { run argv }
+  subject do
+    status = 0
+
+    begin
+      cli.run(argv)
+    rescue SystemExit => e
+      status = e.status
+    end
+
+    OpenStruct.new(status: status, stdout: stdout.string, stderr: stderr.string)
+  end
 
   before do
     ENV["FLIPPER_REQUIRE"] = "./spec/fixtures/environment"
@@ -141,49 +161,4 @@
       it { should have_attributes(status: 0, stdout: /enabled.*admins/m) }
     end
   end
-
-  context "bundler is not installed" do
-    let(:argv) { "list" }
-
-    around do |example|
-      original_bundler = Bundler
-      begin
-        Object.send(:remove_const, :Bundler)
-        example.run
-      ensure
-        Object.const_set(:Bundler, original_bundler)
-      end
-    end
-
-    it "should not raise an error" do
-      Flipper.enable(:enabled_feature)
-      Flipper.enable_group(:enabled_groups, :admins)
-      Flipper.add(:disabled_feature)
-
-      expect(subject).to have_attributes(status: 0, stdout: /enabled_feature.*enabled_groups.*disabled_feature/m)
-    end
-  end
-
-  def run(argv)
-    original_stdout = $stdout
-    original_stderr = $stderr
-
-    $stdout = StringIO.new
-    $stderr = StringIO.new
-    status = 0
-
-    # Prentend this a TTY so we can test colorization
-    allow($stdout).to receive(:tty?).and_return(true)
-
-    begin
-      Flipper::CLI.run(argv)
-    rescue SystemExit => e
-      status = e.status
-    end
-
-    OpenStruct.new(status: status, stdout: $stdout.string, stderr: $stderr.string)
-  ensure
-    $stdout = original_stdout
-    $stderr = original_stderr
-  end
 end