Test officially supported cmd taps. (#390)

All of these taps use Homebrew internal APIs (or will shortly) and we
autoinstall them all from `brew $CMD`. We should adjust our CI to ensure
that we never accidentally break these taps when making changes to core
code so that these taps can rely more on this core code rather than
having to e.g. vendor equivalent code that never changes on our end.

Library/Homebrew/cmd/tests.rb

@@ -1,13 +1,23 @@
 #: @hide_from_man_page
-#:  * `tests` [`-v`] [`--coverage`] [`--generic`] [`--no-compat`] [`--only=`<test_script/test_method>] [`--seed` <seed>] [`--trace`] [`--online`]:
+#:  * `tests` [`-v`] [`--coverage`] [`--generic`] [`--no-compat`] [`--only=`<test_script/test_method>] [`--seed` <seed>] [`--trace`] [`--online`] [`--official-cmd-taps`]:
 #:    Run Homebrew's unit and integration tests.
 
 require "fileutils"
+require "tap"
 
 module Homebrew
   def tests
+    ENV["HOMEBREW_NO_ANALYTICS_THIS_RUN"] = "1"
+
+    if ARGV.include? "--official-cmd-taps"
+      ENV["HOMEBREW_TEST_OFFICIAL_CMD_TAPS"] = "1"
+      OFFICIAL_CMD_TAPS.each do |tap, _|
+        tap = Tap.fetch tap
+        tap.install unless tap.installed?
+      end
+    end
+
     (HOMEBREW_LIBRARY/"Homebrew/test").cd do
-      ENV["HOMEBREW_NO_ANALYTICS_THIS_RUN"] = "1"
       ENV["TESTOPTS"] = "-v" if ARGV.verbose?
       ENV["HOMEBREW_NO_COMPAT"] = "1" if ARGV.include? "--no-compat"
       ENV["HOMEBREW_TEST_GENERIC_OS"] = "1" if ARGV.include? "--generic"

Library/Homebrew/dev-cmd/test-bot.rb

@@ -659,6 +659,7 @@ def homebrew
         test "brew", "tests", *tests_args
         test "brew", "tests", "--no-compat"
         test "brew", "readall", "--syntax"
+        test "brew", "tests", "--official-cmd-taps"
       else
         test "brew", "readall", "--aliases", @tap.name
       end

Library/Homebrew/global.rb

@@ -9,6 +9,7 @@
 require "exceptions"
 require "set"
 require "rbconfig"
+require "official_taps"
 
 ARGV.extend(HomebrewArgvExtension)
 

Library/Homebrew/official_taps.rb

@@ -15,4 +15,10 @@
   tex
   versions
   x11
-]
+].freeze
+
+OFFICIAL_CMD_TAPS = {
+  "caskroom/cask" => ["cask"],
+  "homebrew/bundle" => ["bundle"],
+  "homebrew/services" => ["services"],
+}.freeze

Library/Homebrew/test/test_integration_cmds.rb

@@ -17,6 +17,12 @@ def teardown
     @formula_files.each(&:unlink)
   end
 
+  def needs_test_cmd_taps
+    unless ENV["HOMEBREW_TEST_OFFICIAL_CMD_TAPS"]
+      skip "HOMEBREW_TEST_OFFICIAL_CMD_TAPS is not set"
+    end
+  end
+
   def cmd_id_from_args(args)
     args_pretty = args.join(" ").gsub(TEST_TMPDIR, "@TMPDIR@")
     test_pretty = "#{self.class.name}\##{name}.#{@cmd_id_index += 1}"
@@ -668,4 +674,35 @@ def test_search
   ensure
     desc_cache.unlink
   end
+
+  def test_bundle
+    needs_test_cmd_taps
+    HOMEBREW_REPOSITORY.cd do
+      shutup do
+        system "git", "init"
+        system "git", "commit", "--allow-empty", "-m", "This is a test commit"
+      end
+    end
+
+    mktmpdir do |path|
+      FileUtils.touch "#{path}/Brewfile"
+      Dir.chdir path do
+        assert_equal "The Brewfile's dependencies are satisfied.",
+          cmd("bundle", "check")
+      end
+    end
+  ensure
+    FileUtils.rm_rf HOMEBREW_REPOSITORY/".git"
+  end
+
+  def test_cask
+    needs_test_cmd_taps
+    assert_equal "Warning: nothing to list", cmd("cask", "list")
+  end
+
+  def test_services
+    needs_test_cmd_taps
+    assert_equal "Warning: No services available to control with `brew services`",
+      cmd("services", "list")
+  end
 end

Library/brew.rb

@@ -94,14 +94,8 @@ def require?(path)
     exit Homebrew.failed? ? 1 : 0
   else
     require "tap"
-    possible_tap = case cmd
-    when "brewdle", "brewdler", "bundle", "bundler"
-      Tap.fetch("Homebrew", "bundle")
-    when "cask"
-      Tap.fetch("caskroom", "cask")
-    when "services"
-      Tap.fetch("Homebrew", "services")
-    end
+    possible_tap = OFFICIAL_CMD_TAPS.find { |_, cmds| cmds.include?(cmd) }
+    possible_tap = Tap.fetch(possible_tap.first) if possible_tap
 
     if possible_tap && !possible_tap.installed?
       brew_uid = HOMEBREW_BREW_FILE.stat.uid