cmd/install: upgrade already installed casks

Previously, the behavior was to warn users that a cask was already
installed and then skip modifying the installed version. This is
different to how we handled things with formulas. For them we would
upgrade any already installed formulas. This just brings casks in line
with what we already do with formulas.

Changes:
- cmd/install: Upgrade already installed casks if HOMEBREW_NO_INSTALL_UPGRADE
  is not set
- env_config: Update wording of HOMEBREW_NO_INSTALL_UPGRADE to include casks
- remove error that was only used to alert about already installed casks

Note:
- The upgrade command for casks defaults to --greedy when you pass named casks
  to the command which means that this will always default to that behavior
  since you must specify the name of the cask when installing.

Library/Homebrew/cask/exceptions.rb

@@ -132,21 +132,6 @@ module Cask
     end
   end
 
-  # Error when a cask is already installed.
-  #
-  # @api private
-  class CaskAlreadyInstalledError < AbstractCaskErrorWithToken
-    sig { returns(String) }
-    def to_s
-      <<~EOS
-        Cask '#{token}' is already installed.
-
-        To re-install #{token}, run:
-          #{Formatter.identifier("brew reinstall --cask #{token}")}
-      EOS
-    end
-  end
-
   # Error when there is a cyclic cask dependency.
   #
   # @api private

Library/Homebrew/cask/installer.rb

@@ -91,11 +91,6 @@ module Cask
       Migrator.migrate_if_needed(@cask)
 
       old_config = @cask.config
-      if @cask.installed? && !force? && !reinstall? && !upgrade?
-        return if quiet?
-
-        raise CaskAlreadyInstalledError, @cask
-      end
       predecessor = @cask if reinstall? && @cask.installed?
 
       check_conflicts

Library/Homebrew/cmd/install.rb

@@ -228,8 +228,11 @@ module Homebrew
 
       require "cask/installer"
 
-      casks.each do |cask|
-        Cask::Installer.new(cask,
+      installed_casks, new_casks = casks.partition(&:installed?)
+
+      new_casks.each do |cask|
+        Cask::Installer.new(
+          cask,
           binaries:       args.binaries?,
           verbose:        args.verbose?,
           force:          args.force?,
@@ -237,9 +240,22 @@ module Homebrew
           require_sha:    args.require_sha?,
           skip_cask_deps: args.skip_cask_deps?,
           quarantine:     args.quarantine?,
-                            quiet:          args.quiet?).install
-      rescue Cask::CaskAlreadyInstalledError => e
-        opoo e.message
+          quiet:          args.quiet?,
+        ).install
+      end
+
+      if !Homebrew::EnvConfig.no_install_upgrade? && installed_casks.any?
+        Cask::Upgrade.upgrade_casks(
+          *installed_casks,
+          force:          args.force?,
+          dry_run:        args.dry_run?,
+          binaries:       args.binaries?,
+          quarantine:     args.quarantine?,
+          require_sha:    args.require_sha?,
+          skip_cask_deps: args.skip_cask_deps?,
+          verbose:        args.verbose?,
+          args:           args,
+        )
       end
     end
 

Library/Homebrew/env_config.rb

@@ -315,7 +315,7 @@ module Homebrew
         boolean:     true,
       },
       HOMEBREW_NO_INSTALL_UPGRADE:               {
-        description: "If set, `brew install` <formula> will not upgrade <formula> if it is installed but " \
+        description: "If set, `brew install` <formula/cask> will not upgrade <formula/cask> if it is installed but " \
                      "outdated.",
         boolean:     true,
       },

Library/Homebrew/test/cask/installer_spec.rb

@@ -141,21 +141,6 @@ describe Cask::Installer, :cask do
       end.not_to raise_error
     end
 
-    # unlike the CLI, the internal interface throws exception on double-install
-    it "installer method raises an exception when already-installed Casks are attempted" do
-      transmission = Cask::CaskLoader.load(cask_path("local-transmission"))
-
-      expect(transmission).not_to be_installed
-
-      installer = described_class.new(transmission)
-
-      installer.install
-
-      expect do
-        installer.install
-      end.to raise_error(Cask::CaskAlreadyInstalledError)
-    end
-
     it "allows already-installed Casks to be installed if force is provided" do
       transmission = Cask::CaskLoader.load(cask_path("local-transmission"))
 
@@ -313,7 +298,7 @@ describe Cask::Installer, :cask do
         caffeine = Cask::CaskLoader.load(path)
         expect(caffeine).to receive(:loaded_from_api?).twice.and_return(true)
         expect(caffeine).to receive(:caskfile_only?).twice.and_return(true)
-        expect(caffeine).to receive(:installed_caskfile).twice.and_return(invalid_path)
+        expect(caffeine).to receive(:installed_caskfile).once.and_return(invalid_path)
 
         described_class.new(caffeine).install
         expect(Cask::CaskLoader.load(path)).to be_installed