From b854d5ffe7ee94c9e39a028d81e8c063ac5f4c38 Mon Sep 17 00:00:00 2001
From: Patrick Linnane <patrick@linnane.io>
Date: Fri, 5 Jun 2026 13:30:31 -0700
Subject: [PATCH] generate-cask-ci-matrix: respect `maximum_macos` requirement

Signed-off-by: Patrick Linnane <patrick@linnane.io>
---
 .../dev-cmd/generate-cask-ci-matrix.rb        | 27 ++++---
 .../dev-cmd/generate-cask-ci-matrix_spec.rb   | 81 +++++++++++++++++++
 2 files changed, 96 insertions(+), 12 deletions(-)

diff --git a/Library/Homebrew/dev-cmd/generate-cask-ci-matrix.rb b/Library/Homebrew/dev-cmd/generate-cask-ci-matrix.rb
index 902206ac82..39cd04c38b 100644
--- a/Library/Homebrew/dev-cmd/generate-cask-ci-matrix.rb
+++ b/Library/Homebrew/dev-cmd/generate-cask-ci-matrix.rb
@@ -129,22 +129,25 @@ module Homebrew
       def filter_runners(cask)
         filtered_runners = T.let({}, T::Hash[T::Hash[Symbol, T.any(Symbol, String)], Float])
         if cask.supports_macos?
-          filtered_macos_runners = RUNNERS.select do |runner, _|
-            runner[:symbol] != :linux &&
-              cask.depends_on.macos.present? &&
-              cask.depends_on.macos.allows?(MacOSVersion.from_symbol(runner.fetch(:symbol).to_sym))
-          end
+          # Skip macOS if no runner satisfies the cask's min/max macOS requirements.
+          macos_requirements = [cask.depends_on.macos, cask.depends_on.maximum_macos]
+                               .compact.select(&:version_specified?)
 
-          filtered_runners = if filtered_macos_runners.any?
-            filtered_macos_runners
-          else
+          filtered_runners = if macos_requirements.empty?
             MACOS_RUNNERS.dup
+          else
+            MACOS_RUNNERS.select do |runner, _|
+              macos_version = MacOSVersion.from_symbol(runner.fetch(:symbol).to_sym)
+              macos_requirements.all? { |requirement| requirement.allows?(macos_version) }
+            end
           end
-        end
 
-        macos_archs = architectures(cask:, os: :macos)
-        filtered_runners.select! do |runner, _|
-          macos_archs.include?(runner.fetch(:arch))
+          if filtered_runners.any?
+            macos_archs = architectures(cask:, os: :macos)
+            filtered_runners.select! do |runner, _|
+              macos_archs.include?(runner.fetch(:arch))
+            end
+          end
         end
 
         return filtered_runners unless cask.supports_linux?
diff --git a/Library/Homebrew/test/dev-cmd/generate-cask-ci-matrix_spec.rb b/Library/Homebrew/test/dev-cmd/generate-cask-ci-matrix_spec.rb
index 5dc3587aa1..7708630085 100644
--- a/Library/Homebrew/test/dev-cmd/generate-cask-ci-matrix_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/generate-cask-ci-matrix_spec.rb
@@ -131,6 +131,63 @@ RSpec.describe Homebrew::DevCmd::GenerateCaskCiMatrix do
       app "Test.app"
     end
   end
+  let(:c_minimum_macos) do
+    Cask::Cask.new("test-minimum-macos") do
+      version "0.0.1,2"
+
+      url "https://brew.sh/test-0.0.1.dmg"
+      name "Test"
+      desc "Test cask"
+      homepage "https://brew.sh"
+
+      depends_on macos: :sequoia
+
+      app "Test.app"
+    end
+  end
+  let(:c_maximum_macos) do
+    Cask::Cask.new("test-maximum-macos") do
+      version "0.0.1,2"
+
+      url "https://brew.sh/test-0.0.1.dmg"
+      name "Test"
+      desc "Test cask"
+      homepage "https://brew.sh"
+
+      depends_on maximum_macos: :sonoma
+
+      app "Test.app"
+    end
+  end
+  let(:c_maximum_macos_below_all_runners) do
+    Cask::Cask.new("test-maximum-macos-below-all-runners") do
+      version "0.0.1,2"
+
+      url "https://brew.sh/test-0.0.1.dmg"
+      name "Test"
+      desc "Test cask"
+      homepage "https://brew.sh"
+
+      depends_on maximum_macos: :ventura
+
+      app "Test.app"
+    end
+  end
+  let(:c_minimum_and_maximum_macos) do
+    Cask::Cask.new("test-minimum-and-maximum-macos") do
+      version "0.0.1,2"
+
+      url "https://brew.sh/test-0.0.1.dmg"
+      name "Test"
+      desc "Test cask"
+      homepage "https://brew.sh"
+
+      depends_on macos: :sonoma
+      depends_on maximum_macos: :sequoia
+
+      app "Test.app"
+    end
+  end
   let(:c_linux) do
     Cask::Cask.new("test-linux") do
       version "0.0.1,2"
@@ -218,6 +275,30 @@ RSpec.describe Homebrew::DevCmd::GenerateCaskCiMatrix do
       end
     end
 
+    context "when cask has a macOS version requirement" do
+      it "filters macOS runners by the minimum and maximum macOS requirements" do
+        expect(generate_matrix.filter_runners(c_minimum_macos))
+          .to eq({
+            { arch: :arm, name: "macos-15", symbol: :sequoia }         => 0.0,
+            { arch: :arm, name: "macos-26", symbol: :tahoe }           => 1.0,
+            { arch: :intel, name: "macos-15-intel", symbol: :sequoia } => 1.0,
+          })
+
+        expect(generate_matrix.filter_runners(c_maximum_macos))
+          .to eq({ { arch: :arm, name: "macos-14", symbol: :sonoma } => 0.0 })
+
+        expect(generate_matrix.filter_runners(c_minimum_and_maximum_macos))
+          .to eq({
+            { arch: :arm, name: "macos-14", symbol: :sonoma }          => 0.0,
+            { arch: :arm, name: "macos-15", symbol: :sequoia }         => 0.0,
+            { arch: :intel, name: "macos-15-intel", symbol: :sequoia } => 1.0,
+          })
+
+        # A requirement excluding all runners must skip macOS, not test them all.
+        expect(generate_matrix.filter_runners(c_maximum_macos_below_all_runners)).to eq({})
+      end
+    end
+
     context "when cask only supports Linux" do
       it "returns an array including all Linux" do
         expect(generate_matrix.filter_runners(c_linux))