Add quiet mode for automatic updates

Library/Homebrew/cmd/update_report/reporter_hub.rb

@@ -39,6 +39,8 @@ class ReporterHub
 
   sig { params(auto_update: T::Boolean).void }
   def dump(auto_update: false)
+    return if auto_update && Homebrew::EnvConfig.auto_update_quiet?
+
     unless Homebrew::EnvConfig.no_update_report_new?
       dump_new_formula_report
       dump_new_cask_report

Library/Homebrew/env_config.rb

@@ -96,6 +96,11 @@ module Homebrew
         replacement: "the default behaviour",
         odeprecated: true,
       },
+      HOMEBREW_AUTO_UPDATE_QUIET:                {
+        description: "If set, the auto-update run before commands like `brew install`, `brew upgrade` or " \
+                     "`brew tap` will not show information about new, outdated or deleted formulae and casks.",
+        boolean:     true,
+      },
       HOMEBREW_AUTO_UPDATE_SECS:                 {
         description:  "Run `brew update` once every `$HOMEBREW_AUTO_UPDATE_SECS` seconds before some commands, " \
                       "e.g. `brew install`, `brew upgrade` or `brew tap`. Alternatively, " \

Library/Homebrew/sorbet/rbi/dsl/homebrew/env_config.rbi

@@ -31,6 +31,9 @@ module Homebrew::EnvConfig
     sig { returns(T::Boolean) }
     def ask?; end
 
+    sig { returns(T::Boolean) }
+    def auto_update_quiet?; end
+
     sig { returns(String) }
     def auto_update_secs; end
 

Library/Homebrew/test/cmd/update-report_spec.rb

@@ -638,6 +638,22 @@ RSpec.describe Homebrew::Cmd::UpdateReport do
       EOS
     end
 
+    it "does not dump update details when HOMEBREW_AUTO_UPDATE_QUIET is set during auto-update" do
+      ENV["HOMEBREW_AUTO_UPDATE_QUIET"] = "1"
+      allow(hub).to receive(:select_formula_or_cask).with(:A).and_return(["foo"])
+      allow(hub).to receive(:installed?).and_return(false)
+
+      expect { hub.dump(auto_update: true) }.not_to output.to_stdout
+    end
+
+    it "dumps update details when HOMEBREW_AUTO_UPDATE_QUIET is set during an explicit update" do
+      ENV["HOMEBREW_AUTO_UPDATE_QUIET"] = "1"
+      allow(hub).to receive(:select_formula_or_cask).with(:A).and_return(["foo"])
+      allow(hub).to receive_messages(installed?: false, description: nil)
+
+      expect { hub.dump }.to output("==> New Formulae\nfoo\n").to_stdout
+    end
+
     it "dumps deleted installed formulae and casks report" do
       allow(hub).to receive(:select_formula_or_cask).with(:D).and_return(["baz", "foo", "bar"])
       allow(hub).to receive(:installed?).with("baz").and_return(true)

docs/Manpage.md

@@ -4335,6 +4335,12 @@ command execution (e.g. `$(cat file)`).
   are both set, if the request to `$HOMEBREW_ARTIFACT_DOMAIN` fails then
   Homebrew will error rather than trying any other/default URLs.
 
+`HOMEBREW_AUTO_UPDATE_QUIET`
+
+: If set, the auto-update run before commands like `brew install`, `brew
+  upgrade` or `brew tap` will not show information about new, outdated or
+  deleted formulae and casks.
+
 `HOMEBREW_AUTO_UPDATE_SECS`
 
 : Run `brew update` once every `$HOMEBREW_AUTO_UPDATE_SECS` seconds before some

manpages/brew.1

@@ -2758,6 +2758,9 @@ Prefix all download URLs, including those for bottles, with this value\. For exa
 \fBHOMEBREW_ARTIFACT_DOMAIN_NO_FALLBACK\fP
 When \fB$HOMEBREW_ARTIFACT_DOMAIN\fP and \fB$HOMEBREW_ARTIFACT_DOMAIN_NO_FALLBACK\fP are both set, if the request to \fB$HOMEBREW_ARTIFACT_DOMAIN\fP fails then Homebrew will error rather than trying any other/default URLs\.
 .TP
+\fBHOMEBREW_AUTO_UPDATE_QUIET\fP
+If set, the auto\-update run before commands like \fBbrew install\fP, \fBbrew upgrade\fP or \fBbrew tap\fP will not show information about new, outdated or deleted formulae and casks\.
+.TP
 \fBHOMEBREW_AUTO_UPDATE_SECS\fP
 Run \fBbrew update\fP once every \fB$HOMEBREW_AUTO_UPDATE_SECS\fP seconds before some commands, e\.g\. \fBbrew install\fP, \fBbrew upgrade\fP or \fBbrew tap\fP\&\. Alternatively, disable auto\-update entirely with \fB$HOMEBREW_NO_AUTO_UPDATE\fP\&\.
 .RS