test/bundle: add additional test coverage.

Add missing test coverage, requires, fix a TODO and remove `needs_macos`
from a cask test.

Library/Homebrew/bundle/brew_installer.rb

@@ -67,8 +67,7 @@ module Homebrew
             else
               Formula[@full_name].version
             end.to_s
-            version_path = Pathname.new(@version_file)
-            version_path.write("#{version}\n")
+            File.write(@version_file, "#{version}\n")
 
             puts "Wrote #{@name} version #{version} to #{@version_file}" if verbose
           end

Library/Homebrew/test/bundle/brew_installer_spec.rb

@@ -260,6 +260,40 @@ RSpec.describe Homebrew::Bundle::BrewInstaller do
         end
       end
     end
+
+    context "when the version_file option is provided" do
+      before do
+        Homebrew::Bundle.reset!
+
+        allow_any_instance_of(described_class).to receive(:install_change_state!).and_return(true)
+        allow_any_instance_of(described_class).to receive(:installed?).and_return(true)
+        allow_any_instance_of(described_class).to receive(:linked?).and_return(true)
+      end
+
+      let(:version_file) { "version.txt" }
+      let(:version) { "1.0" }
+
+      context "when formula versions are changed and specified by the environment" do
+        before do
+          allow_any_instance_of(described_class).to receive(:changed?).and_return(false)
+          ENV["HOMEBREW_BUNDLE_EXEC_FORMULA_VERSION_#{formula_name.upcase}"] = version
+        end
+
+        it "writes the version to the file" do
+          expect(File).to receive(:write).with(version_file, "#{version}\n")
+          described_class.preinstall(formula_name, version_file:)
+          described_class.install(formula_name, version_file:)
+        end
+      end
+
+      context "when using the latest formula" do
+        it "writes the version to the file" do
+          expect(File).to receive(:write).with(version_file, "#{version}\n")
+          described_class.preinstall(formula_name, version_file:)
+          described_class.install(formula_name, version_file:)
+        end
+      end
+    end
   end
 
   context "when a formula isn't installed" do

Library/Homebrew/test/bundle/commands/check_spec.rb

@@ -3,6 +3,7 @@
 require "bundle"
 require "bundle/commands/check"
 require "bundle/brew_checker"
+require "bundle/cask_checker"
 require "bundle/mac_app_store_checker"
 require "bundle/vscode_extension_checker"
 require "bundle/brew_installer"
@@ -56,11 +57,23 @@ RSpec.describe Homebrew::Bundle::Commands::Check do
   end
 
   context "when formulae are not installed" do
-    it "raises an error" do
+    let(:verbose) { true }
+
+    it "raises an error and outputs to stdout" do
       allow(Homebrew::Bundle::CaskDumper).to receive(:casks).and_return([])
       allow(Homebrew::Bundle::BrewInstaller).to receive(:upgradable_formulae).and_return([])
       allow_any_instance_of(Pathname).to receive(:read).and_return("brew 'abc'")
-      expect { do_check }.to raise_error(SystemExit)
+      expect { do_check }.to raise_error(SystemExit).and \
+        output(/brew bundle can't satisfy your Brewfile's dependencies/).to_stdout
+    end
+
+    it "partially outputs when HOMEBREW_BUNDLE_CHECK_ALREADY_OUTPUT_FORMULAE_ERRORS is set" do
+      allow(Homebrew::Bundle::CaskDumper).to receive(:casks).and_return([])
+      allow(Homebrew::Bundle::BrewInstaller).to receive(:upgradable_formulae).and_return([])
+      allow_any_instance_of(Pathname).to receive(:read).and_return("brew 'abc'")
+      ENV["HOMEBREW_BUNDLE_CHECK_ALREADY_OUTPUT_FORMULAE_ERRORS"] = "abc"
+      expect { do_check }.to raise_error(SystemExit).and \
+        output("Satisfy missing dependencies with `brew bundle install`.\n").to_stdout
     end
 
     it "does not raise error on skippable formula" do

Library/Homebrew/test/bundle/skipper_spec.rb

@@ -27,19 +27,16 @@ RSpec.describe Homebrew::Bundle::Skipper do
       end
     end
 
-    context "with an unbottled formula on ARM", :needs_macos do
+    context "with an unbottled formula on ARM" do
       let(:entry) { Homebrew::Bundle::Dsl::Entry.new(:brew, "mysql") }
 
-      # TODO: remove OpenStruct usage
-      # rubocop:todo Style/OpenStructUse
       it "returns true" do
         allow(Hardware::CPU).to receive(:arm?).and_return(true)
-        allow_any_instance_of(Formula).to receive(:stable).and_return(OpenStruct.new(bottled?:        false,
-                                                                                     bottle_defined?: true))
+        allow(Homebrew).to receive(:default_prefix?).and_return(true)
+        stub_formula_loader formula("mysql") { url "mysql-1.0" }
 
         expect(skipper.skip?(entry)).to be true
       end
-      # rubocop:enable Style/OpenStructUse
     end
 
     context "with an unlisted cask", :needs_macos do