test/keg_relocate/binary_relocation_spec.rb: add new unit test

Library/Homebrew/test/keg_relocate/binary_relocation_spec.rb

@@ -0,0 +1,44 @@
+# typed: false
+# frozen_string_literal: true
+
+require "keg_relocate"
+
+describe Keg do
+  subject(:keg) { described_class.new(HOMEBREW_CELLAR/"foo/1.0.0") }
+
+  let(:dir) { HOMEBREW_CELLAR/"foo/1.0.0" }
+  let(:newdir) { HOMEBREW_CELLAR/"foo" }
+  let(:binary_file) { dir/"file.bin" }
+
+  before do
+    dir.mkpath
+  end
+
+  def setup_binary_file
+    binary_file.atomic_write <<~EOS
+      \x00#{dir}\x00
+    EOS
+  end
+
+  describe "#relocate_build_prefix" do
+    specify "replace prefix in binary files" do
+      setup_binary_file
+
+      keg.relocate_build_prefix(keg, dir, newdir)
+
+      old_prefix_matches = Set.new
+      keg.each_unique_file_matching(dir) do |file|
+        old_prefix_matches << file
+      end
+
+      expect(old_prefix_matches.size).to eq 0
+
+      new_prefix_matches = Set.new
+      keg.each_unique_file_matching(newdir) do |file|
+        new_prefix_matches << file
+      end
+
+      expect(new_prefix_matches.size).to eq 1
+    end
+  end
+end