diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index eeaaf127d7..a028176c93 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -1546,3 +1546,5 @@ on_request: installed_on_request?, options:)
     $stderr.puts @requirement_messages
   end
 end
+
+require "extend/os/formula_installer"
diff --git a/Library/Homebrew/test/formula_installer_spec.rb b/Library/Homebrew/test/formula_installer_spec.rb
index d4b6284b3d..43906c1c9e 100644
--- a/Library/Homebrew/test/formula_installer_spec.rb
+++ b/Library/Homebrew/test/formula_installer_spec.rb
@@ -450,6 +450,27 @@ RSpec.describe FormulaInstaller do
     end
   end
 
+  describe "#fresh_install" do
+    subject(:formula_installer) { described_class.new(Testball.new) }
+
+    it "is false by default" do
+      formula = Testball.new
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+
+    it "is false in developer mode" do
+      formula = Testball.new
+      allow(Homebrew::EnvConfig).to receive_messages(developer?: true)
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+
+    it "is false on outdated releases" do
+      formula = Testball.new
+      allow(OS::Mac.version).to receive_messages(outdated_release?: true)
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+  end
+
   describe "#install_service" do
     it "works if service is set" do
       formula = Testball.new
diff --git a/Library/Homebrew/test/os/linux/formula_installer_spec.rb b/Library/Homebrew/test/os/linux/formula_installer_spec.rb
new file mode 100644
index 0000000000..f5c47599de
--- /dev/null
+++ b/Library/Homebrew/test/os/linux/formula_installer_spec.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require "formula_installer"
+require "test/support/fixtures/testball"
+
+RSpec.describe FormulaInstaller do
+  include FileUtils
+
+  subject(:keg) { described_class.new(keg_path) }
+
+  describe "#fresh_install" do
+    subject(:formula_installer) { described_class.new(Testball.new) }
+
+    it "is true by default" do
+      formula = Testball.new
+      expect(formula_installer.fresh_install?(formula)).to be true
+    end
+
+    it "is false in developer mode" do
+      formula = Testball.new
+      allow(Homebrew::EnvConfig).to receive_messages(developer?: true)
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+  end
+end
diff --git a/Library/Homebrew/test/os/mac/formula_installer_spec.rb b/Library/Homebrew/test/os/mac/formula_installer_spec.rb
new file mode 100644
index 0000000000..21b83da6c3
--- /dev/null
+++ b/Library/Homebrew/test/os/mac/formula_installer_spec.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "formula_installer"
+require "test/support/fixtures/testball"
+
+RSpec.describe FormulaInstaller do
+  include FileUtils
+
+  subject(:keg) { described_class.new(keg_path) }
+
+  describe "#fresh_install" do
+    subject(:formula_installer) { described_class.new(Testball.new) }
+
+    it "is true by default" do
+      formula = Testball.new
+      expect(formula_installer.fresh_install?(formula)).to be true
+    end
+
+    it "is false in developer mode" do
+      formula = Testball.new
+      allow(Homebrew::EnvConfig).to receive_messages(developer?: true)
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+
+    it "is false on outdated releases" do
+      formula = Testball.new
+      allow(OS::Mac.version).to receive_messages(outdated_release?: true)
+      expect(formula_installer.fresh_install?(formula)).to be false
+    end
+  end
+end