Add test for Cask::Utils::gain_permissions_mkpath.

Library/Homebrew/test/cask/utils_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+describe Cask::Utils do
+  let(:command) { NeverSudoSystemCommand }
+
+  describe "::gain_permissions_mkpath" do
+    let(:dir) { mktmpdir }
+    let(:path) { dir/"a/b/c" }
+
+    it "creates a directory" do
+      expect(path).not_to exist
+      described_class.gain_permissions_mkpath path, command: command
+      expect(path).to be_a_directory
+      described_class.gain_permissions_mkpath path, command: command
+      expect(path).to be_a_directory
+    end
+
+    context "when parent directory is not writable" do
+      it "creates a directory with `sudo`" do
+        FileUtils.chmod "-w", dir
+        expect(dir).not_to be_writable
+
+        expect(command).to receive(:run!).exactly(:once).and_wrap_original do |original, *args, **options|
+          FileUtils.chmod "+w", dir
+          original.call(*args, **options)
+          FileUtils.chmod "-w", dir
+        end
+
+        expect(path).not_to exist
+        described_class.gain_permissions_mkpath path, command: command
+        expect(path).to be_a_directory
+        described_class.gain_permissions_mkpath path, command: command
+        expect(path).to be_a_directory
+
+        expect(dir).not_to be_writable
+        FileUtils.chmod "+w", dir
+      end
+    end
+  end
+end