look for Brewfile in HOMEBREW_USER_CONFIG_HOME

cmd/bundle.rb

@@ -56,8 +56,8 @@ class BundleCmd < AbstractCommand
         flag "--file=",
              description: "Read the `Brewfile` from this location. Use `--file=-` to pipe to stdin/stdout."
         switch "--global",
-               description: "Read the `Brewfile` from `~/.Brewfile` or " \
-                            "the `HOMEBREW_BUNDLE_FILE_GLOBAL` environment variable, if set."
+               description: "Read the global `Brewfile`, from the homebrew config directory or `~/.Brewfile`. " \
+                            "Override this path with the `HOMEBREW_BUNDLE_FILE_GLOBAL` environment variable."
         switch "-v", "--verbose",
                description: "`install` prints output from commands as they are run. " \
                             "`check` lists all missing dependencies."

lib/bundle/brewfile.rb

@@ -7,15 +7,20 @@ module Brewfile
     def path(dash_writes_to_stdout: false, global: false, file: nil)
       env_bundle_file_global = ENV.fetch("HOMEBREW_BUNDLE_FILE_GLOBAL", nil)
       env_bundle_file = ENV.fetch("HOMEBREW_BUNDLE_FILE", nil)
+      user_config_home = ENV.fetch("HOMEBREW_USER_CONFIG_HOME", nil)
 
       filename = if global
         if env_bundle_file_global.present?
           env_bundle_file_global
         else
           raise "'HOMEBREW_BUNDLE_FILE' cannot be specified with '--global'" if env_bundle_file.present?
 
-          Bundle.exchange_uid_if_needed! do
-            "#{Dir.home}/.Brewfile"
+          if user_config_home && File.exist?("#{user_config_home}/Brewfile")
+            "#{user_config_home}/Brewfile"
+          else
+            Bundle.exchange_uid_if_needed! do
+              "#{Dir.home}/.Brewfile"
+            end
           end
         end
       elsif file.present?

spec/bundle/brewfile_spec.rb

@@ -11,15 +11,22 @@
     let(:dash_writes_to_stdout) { false }
     let(:env_bundle_file_global_value) { nil }
     let(:env_bundle_file_value) { nil }
+    let(:env_user_config_home_value) { "/Users/username/.homebrew" }
     let(:file_value) { nil }
     let(:has_global) { false }
+    let(:config_dir_brewfile_exist) { false }
 
     before do
       allow(ENV).to receive(:fetch).and_return(nil)
       allow(ENV).to receive(:fetch).with("HOMEBREW_BUNDLE_FILE_GLOBAL", any_args)
                                    .and_return(env_bundle_file_global_value)
       allow(ENV).to receive(:fetch).with("HOMEBREW_BUNDLE_FILE", any_args)
                                    .and_return(env_bundle_file_value)
+
+      allow(ENV).to receive(:fetch).with("HOMEBREW_USER_CONFIG_HOME", any_args)
+                                   .and_return(env_user_config_home_value)
+      allow(File).to receive(:exist?).with("/Users/username/.homebrew/Brewfile")
+                                     .and_return(config_dir_brewfile_exist)
     end
 
     context "when `file` is specified with a relative path" do
@@ -154,6 +161,15 @@
           expect(path).to eq(expected_pathname)
         end
       end
+
+      context "when HOMEBREW_USER_CONFIG_HOME/Brewfile exists" do
+        let(:config_dir_brewfile_exist) { true }
+        let(:expected_pathname) { Pathname.new("#{env_user_config_home_value}/Brewfile") }
+
+        it "returns the expected path" do
+          expect(path).to eq(expected_pathname)
+        end
+      end
     end
 
     context "when HOMEBREW_BUNDLE_FILE has a value" do