Refactor unpack strategies into separate files.

Library/Homebrew/download_strategy.rb

@@ -329,7 +329,7 @@ end
 # Useful for installing jars.
 class NoUnzipCurlDownloadStrategy < CurlDownloadStrategy
   def stage
-    UncompressedUnpackStrategy.new(cached_location)
+    UnpackStrategy::Uncompressed.new(cached_location)
                                 .extract(basename: basename_without_params)
   end
 end

Library/Homebrew/test/unpack_strategy/bazaar_spec.rb

@@ -0,0 +1,14 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Bazaar do
+  let(:repo) {
+    mktmpdir.tap do |repo|
+      FileUtils.touch repo/"test"
+      (repo/".bzr").mkpath
+    end
+  }
+  let(:path) { repo }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["test"]
+end

Library/Homebrew/test/unpack_strategy/bzip2_spec.rb

@@ -0,0 +1,8 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Bzip2 do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.bz2" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["container"]
+end

Library/Homebrew/test/unpack_strategy/cvs_spec.rb

@@ -0,0 +1,14 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Cvs do
+  let(:repo) {
+    mktmpdir.tap do |repo|
+      FileUtils.touch repo/"test"
+      (repo/"CVS").mkpath
+    end
+  }
+  let(:path) { repo }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["CVS", "test"]
+end

Library/Homebrew/test/unpack_strategy/directory_spec.rb

@@ -0,0 +1,32 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Directory do
+  let(:path) {
+    mktmpdir.tap do |path|
+      FileUtils.touch path/"file"
+      FileUtils.ln_s "file", path/"symlink"
+    end
+  }
+  subject(:strategy) { described_class.new(path) }
+  let(:unpack_dir) { mktmpdir }
+
+  it "does not follow symlinks" do
+    strategy.extract(to: unpack_dir)
+    expect(unpack_dir/"symlink").to be_a_symlink
+  end
+
+  it "preserves permissions of contained files" do
+    FileUtils.chmod 0644, path/"file"
+
+    strategy.extract(to: unpack_dir)
+    expect((unpack_dir/"file").stat.mode & 0777).to eq 0644
+  end
+
+  it "preserves the permissions of the destination directory" do
+    FileUtils.chmod 0700, path
+    FileUtils.chmod 0755, unpack_dir
+
+    strategy.extract(to: unpack_dir)
+    expect(unpack_dir.stat.mode & 0777).to eq 0755
+  end
+end

Library/Homebrew/test/unpack_strategy/git_spec.rb

@@ -0,0 +1,17 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Git do
+  let(:repo) {
+    mktmpdir.tap do |repo|
+      system "git", "-C", repo, "init"
+
+      FileUtils.touch repo/"test"
+      system "git", "-C", repo, "add", "test"
+      system "git", "-C", repo, "commit", "-m", "Add `test` file."
+    end
+  }
+  let(:path) { repo }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: [".git", "test"]
+end

Library/Homebrew/test/unpack_strategy/gzip_spec.rb

@@ -0,0 +1,8 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Gzip do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.gz" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["container"]
+end

Library/Homebrew/test/unpack_strategy/jar_spec.rb

@@ -0,0 +1,8 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Jar do
+  let(:path) { TEST_FIXTURE_DIR/"test.jar" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["test.jar"]
+end

Library/Homebrew/test/unpack_strategy/lha_spec.rb

@@ -0,0 +1,7 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Lha do
+  let(:path) { TEST_FIXTURE_DIR/"test.lha" }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/lzip_spec.rb

@@ -0,0 +1,7 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Lzip do
+  let(:path) { TEST_FIXTURE_DIR/"test.lz" }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/mercurial_spec.rb

@@ -0,0 +1,12 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Mercurial do
+  let(:repo) {
+    mktmpdir.tap do |repo|
+      (repo/".hg").mkpath
+    end
+  }
+  let(:path) { repo }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/p7zip_spec.rb

@@ -0,0 +1,7 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::P7Zip do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.7z" }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/rar_spec.rb

@@ -0,0 +1,7 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Rar do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.rar" }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/shared_examples.rb

@@ -0,0 +1,16 @@
+require "unpack_strategy"
+
+shared_examples "UnpackStrategy::detect" do
+  it "is correctly detected" do
+    expect(UnpackStrategy.detect(path)).to be_a described_class
+  end
+end
+
+shared_examples "#extract" do |children: []|
+  specify "#extract" do
+    mktmpdir do |unpack_dir|
+      described_class.new(path).extract(to: unpack_dir)
+      expect(unpack_dir.children(false).map(&:to_s)).to match_array children
+    end
+  end
+end

Library/Homebrew/test/unpack_strategy/subversion_spec.rb

@@ -0,0 +1,22 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Subversion do
+  let(:repo) {
+    mktmpdir.tap do |repo|
+      system "svnadmin", "create", repo
+    end
+  }
+  let(:working_copy) {
+    mktmpdir.tap do |working_copy|
+      system "svn", "checkout", "file://#{repo}", working_copy
+
+      FileUtils.touch working_copy/"test"
+      system "svn", "add", working_copy/"test"
+      system "svn", "commit", working_copy, "-m", "Add `test` file."
+    end
+  }
+  let(:path) { working_copy }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["test"]
+end

Library/Homebrew/test/unpack_strategy/tar_spec.rb

@@ -0,0 +1,18 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Tar do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.tar.gz" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["container"]
+
+  context "when TAR archive is corrupted" do
+    let(:path) {
+      (mktmpdir/"test.tar").tap do |path|
+        FileUtils.touch path
+      end
+    }
+
+    include_examples "UnpackStrategy::detect"
+  end
+end

Library/Homebrew/test/unpack_strategy/uncompressed_spec.rb

@@ -0,0 +1,11 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Uncompressed do
+  let(:path) {
+    (mktmpdir/"test").tap do |path|
+      FileUtils.touch path
+    end
+  }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/xar_spec.rb

@@ -0,0 +1,8 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Xar, :needs_macos do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.xar" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["container"]
+end

Library/Homebrew/test/unpack_strategy/xz_spec.rb

@@ -0,0 +1,7 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Xz do
+  let(:path) { TEST_FIXTURE_DIR/"cask/container.xz" }
+
+  include_examples "UnpackStrategy::detect"
+end

Library/Homebrew/test/unpack_strategy/zip_spec.rb

@@ -0,0 +1,18 @@
+require_relative "shared_examples"
+
+describe UnpackStrategy::Zip do
+  let(:path) { TEST_FIXTURE_DIR/"cask/MyFancyApp.zip" }
+
+  include_examples "UnpackStrategy::detect"
+  include_examples "#extract", children: ["MyFancyApp"]
+
+  context "when ZIP archive is corrupted" do
+    let(:path) {
+      (mktmpdir/"test.zip").tap do |path|
+        FileUtils.touch path
+      end
+    }
+
+    include_examples "UnpackStrategy::detect"
+  end
+end

Library/Homebrew/test/unpack_strategy_spec.rb

@@ -1,20 +1,3 @@
-require "unpack_strategy"
-
-RSpec.shared_examples "UnpackStrategy::detect" do
-  it "is correctly detected" do
-    expect(UnpackStrategy.detect(path)).to be_a described_class
-  end
-end
-
-RSpec.shared_examples "#extract" do |children: []|
-  specify "#extract" do
-    mktmpdir do |unpack_dir|
-      described_class.new(path).extract(to: unpack_dir)
-      expect(unpack_dir.children(false).map(&:to_s)).to match_array children
-    end
-  end
-end
-
 describe UnpackStrategy do
   describe "#extract_nestedly" do
     subject(:strategy) { described_class.detect(path) }
@@ -75,210 +58,3 @@ describe UnpackStrategy do
     end
   end
 end
-
-describe DirectoryUnpackStrategy do
-  let(:path) {
-    mktmpdir.tap do |path|
-      FileUtils.touch path/"file"
-      FileUtils.ln_s "file", path/"symlink"
-    end
-  }
-  subject(:strategy) { described_class.new(path) }
-  let(:unpack_dir) { mktmpdir }
-
-  it "does not follow symlinks" do
-    strategy.extract(to: unpack_dir)
-    expect(unpack_dir/"symlink").to be_a_symlink
-  end
-
-  it "preserves permissions of contained files" do
-    FileUtils.chmod 0644, path/"file"
-
-    strategy.extract(to: unpack_dir)
-    expect((unpack_dir/"file").stat.mode & 0777).to eq 0644
-  end
-
-  it "preserves the permissions of the destination directory" do
-    FileUtils.chmod 0700, path
-    FileUtils.chmod 0755, unpack_dir
-
-    strategy.extract(to: unpack_dir)
-    expect(unpack_dir.stat.mode & 0777).to eq 0755
-  end
-end
-
-describe UncompressedUnpackStrategy do
-  let(:path) {
-    (mktmpdir/"test").tap do |path|
-      FileUtils.touch path
-    end
-  }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe P7ZipUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.7z" }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe XarUnpackStrategy, :needs_macos do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.xar" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["container"]
-end
-
-describe XzUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.xz" }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe RarUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.rar" }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe LzipUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"test.lz" }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe LhaUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"test.lha" }
-
-  include_examples "UnpackStrategy::detect"
-end
-
-describe JarUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"test.jar" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["test.jar"]
-end
-
-describe ZipUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/MyFancyApp.zip" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["MyFancyApp"]
-
-  context "when ZIP archive is corrupted" do
-    let(:path) {
-      (mktmpdir/"test.zip").tap do |path|
-        FileUtils.touch path
-      end
-    }
-
-    include_examples "UnpackStrategy::detect"
-  end
-end
-
-describe GzipUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.gz" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["container"]
-end
-
-describe Bzip2UnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.bz2" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["container"]
-end
-
-describe TarUnpackStrategy do
-  let(:path) { TEST_FIXTURE_DIR/"cask/container.tar.gz" }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["container"]
-
-  context "when TAR archive is corrupted" do
-    let(:path) {
-      (mktmpdir/"test.tar").tap do |path|
-        FileUtils.touch path
-      end
-    }
-
-    include_examples "UnpackStrategy::detect"
-  end
-end
-
-describe GitUnpackStrategy do
-  let(:repo) {
-    mktmpdir.tap do |repo|
-      system "git", "-C", repo, "init"
-
-      FileUtils.touch repo/"test"
-      system "git", "-C", repo, "add", "test"
-      system "git", "-C", repo, "commit", "-m", "Add `test` file."
-    end
-  }
-  let(:path) { repo }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: [".git", "test"]
-end
-
-describe SubversionUnpackStrategy do
-  let(:repo) {
-    mktmpdir.tap do |repo|
-      system "svnadmin", "create", repo
-    end
-  }
-  let(:working_copy) {
-    mktmpdir.tap do |working_copy|
-      system "svn", "checkout", "file://#{repo}", working_copy
-
-      FileUtils.touch working_copy/"test"
-      system "svn", "add", working_copy/"test"
-      system "svn", "commit", working_copy, "-m", "Add `test` file."
-    end
-  }
-  let(:path) { working_copy }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["test"]
-end
-
-describe CvsUnpackStrategy do
-  let(:repo) {
-    mktmpdir.tap do |repo|
-      FileUtils.touch repo/"test"
-      (repo/"CVS").mkpath
-    end
-  }
-  let(:path) { repo }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["CVS", "test"]
-end
-
-describe BazaarUnpackStrategy do
-  let(:repo) {
-    mktmpdir.tap do |repo|
-      FileUtils.touch repo/"test"
-      (repo/".bzr").mkpath
-    end
-  }
-  let(:path) { repo }
-
-  include_examples "UnpackStrategy::detect"
-  include_examples "#extract", children: ["test"]
-end
-
-describe MercurialUnpackStrategy do
-  let(:repo) {
-    mktmpdir.tap do |repo|
-      (repo/".hg").mkpath
-    end
-  }
-  let(:path) { repo }
-
-  include_examples "UnpackStrategy::detect"
-end

Library/Homebrew/unpack_strategy.rb

@@ -1,30 +1,30 @@
-class UnpackStrategy
-  # length of the longest regex (currently TarUnpackStrategy)
+module UnpackStrategy
+  # length of the longest regex (currently Tar)
   MAX_MAGIC_NUMBER_LENGTH = 262
   private_constant :MAX_MAGIC_NUMBER_LENGTH
 
   def self.strategies
     @strategies ||= [
-      JarUnpackStrategy,
-      LuaRockUnpackStrategy,
-      MicrosoftOfficeXmlUnpackStrategy,
-      ZipUnpackStrategy,
-      XarUnpackStrategy,
-      CompressUnpackStrategy,
-      TarUnpackStrategy,
-      GzipUnpackStrategy,
-      Bzip2UnpackStrategy,
-      XzUnpackStrategy,
-      LzipUnpackStrategy,
-      GitUnpackStrategy,
-      MercurialUnpackStrategy,
-      SubversionUnpackStrategy,
-      CvsUnpackStrategy,
-      FossilUnpackStrategy,
-      BazaarUnpackStrategy,
-      P7ZipUnpackStrategy,
-      RarUnpackStrategy,
-      LhaUnpackStrategy,
+      Jar,
+      LuaRock,
+      MicrosoftOfficeXml,
+      Zip,
+      Xar,
+      Compress,
+      Tar,
+      Gzip,
+      Bzip2,
+      Xz,
+      Lzip,
+      Git,
+      Mercurial,
+      Subversion,
+      Cvs,
+      Fossil,
+      Bazaar,
+      P7Zip,
+      Rar,
+      Lha,
     ].freeze
   end
   private_class_method :strategies
@@ -43,11 +43,11 @@ class UnpackStrategy
     # This is so that bad files produce good error messages.
     strategy ||= case path.extname
     when ".tar", ".tar.gz", ".tgz", ".tar.bz2", ".tbz", ".tar.xz", ".txz"
-      TarUnpackStrategy
+      Tar
     when ".zip"
-      ZipUnpackStrategy
+      Zip
     else
-      UncompressedUnpackStrategy
+      Uncompressed
     end
 
     strategy.new(path, ref_type: ref_type, ref: ref)
@@ -77,301 +77,36 @@ class UnpackStrategy
       children = tmp_unpack_dir.children
 
       if children.count == 1 && !children.first.directory?
-        s = self.class.detect(children.first)
+        s = UnpackStrategy.detect(children.first)
 
         s.extract_nestedly(to: to, verbose: verbose)
         next
       end
 
-      DirectoryUnpackStrategy.new(tmp_unpack_dir).extract(to: to, verbose: verbose)
+      Directory.new(tmp_unpack_dir).extract(to: to, verbose: verbose)
     end
   end
 end
 
-class DirectoryUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    path.directory?
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    path.children.each do |child|
-      FileUtils.copy_entry child, unpack_dir/child.basename, true, false
-    end
-  end
-end
-
-class UncompressedUnpackStrategy < UnpackStrategy
-  alias extract_nestedly extract
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    FileUtils.cp path, unpack_dir/basename, preserve: true, verbose: verbose
-  end
-end
-
-class MicrosoftOfficeXmlUnpackStrategy < UncompressedUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    return false unless ZipUnpackStrategy.can_extract?(path: path, magic_number: magic_number)
-
-    # Check further if the ZIP is a Microsoft Office XML document.
-    magic_number.match?(/\APK\003\004/n) &&
-      magic_number.match?(%r{\A.{30}(\[Content_Types\]\.xml|_rels/\.rels)}n)
-  end
-end
-
-class LuaRockUnpackStrategy < UncompressedUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    return false unless ZipUnpackStrategy.can_extract?(path: path, magic_number: magic_number)
-
-    # Check further if the ZIP is a LuaRocks package.
-    out, = Open3.capture3("zipinfo", "-1", path)
-    out.encode(Encoding::UTF_8, invalid: :replace)
-       .split("\n")
-       .any? { |line| line.match?(%r{\A[^/]+.rockspec\Z}) }
-  end
-end
-
-class JarUnpackStrategy < UncompressedUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    return false unless ZipUnpackStrategy.can_extract?(path: path, magic_number: magic_number)
-
-    # Check further if the ZIP is a JAR/WAR.
-    out, = Open3.capture3("zipinfo", "-1", path)
-    out.encode(Encoding::UTF_8, invalid: :replace)
-       .split("\n")
-       .include?("META-INF/MANIFEST.MF")
-  end
-end
-
-class P7ZipUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\A7z\xBC\xAF\x27\x1C/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system "7zr", "x", "-y", "-bd", "-bso0", path, "-o#{unpack_dir}"
-  end
-end
-
-class ZipUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\APK(\003\004|\005\006)/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    quiet_flags = verbose ? [] : ["-qq"]
-    safe_system "unzip", *quiet_flags, path, "-d", unpack_dir
-  end
-end
-
-class TarUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    return true if magic_number.match?(/\A.{257}ustar/n)
-
-    # Check if `tar` can list the contents, then it can also extract it.
-    IO.popen(["tar", "tf", path], err: File::NULL) do |stdout|
-      !stdout.read(1).nil?
-    end
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system "tar", "xf", path, "-C", unpack_dir
-  end
-end
-
-class CompressUnpackStrategy < TarUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\A\037\235/n)
-  end
-end
-
-class XzUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\A\xFD7zXZ\x00/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    FileUtils.cp path, unpack_dir/basename, preserve: true
-    quiet_flags = verbose ? [] : ["-q"]
-    safe_system Formula["xz"].opt_bin/"unxz", *quiet_flags, "-T0", unpack_dir/basename
-    extract_nested_tar(unpack_dir)
-  end
-
-  def extract_nested_tar(unpack_dir)
-    return unless DependencyCollector.tar_needs_xz_dependency?
-    return if (children = unpack_dir.children).count != 1
-    return if (tar = children.first).extname != ".tar"
-
-    Dir.mktmpdir do |tmpdir|
-      tmpdir = Pathname(tmpdir)
-      FileUtils.mv tar, tmpdir/tar.basename
-      TarUnpackStrategy.new(tmpdir/tar.basename).extract(to: unpack_dir)
-    end
-  end
-end
-
-class Bzip2UnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\ABZh/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    FileUtils.cp path, unpack_dir/basename, preserve: true
-    quiet_flags = verbose ? [] : ["-q"]
-    safe_system "bunzip2", *quiet_flags, unpack_dir/basename
-  end
-end
-
-class GzipUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\A\037\213/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    FileUtils.cp path, unpack_dir/basename, preserve: true
-    quiet_flags = verbose ? [] : ["-q"]
-    safe_system "gunzip", *quiet_flags, "-N", unpack_dir/basename
-  end
-end
-
-class LzipUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\ALZIP/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    FileUtils.cp path, unpack_dir/basename, preserve: true
-    quiet_flags = verbose ? [] : ["-q"]
-    safe_system Formula["lzip"].opt_bin/"lzip", "-d", *quiet_flags, unpack_dir/basename
-  end
-end
-
-class XarUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\Axar!/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system "xar", "-x", "-f", path, "-C", unpack_dir
-  end
-end
-
-class RarUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\ARar!/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system Formula["unrar"].opt_bin/"unrar", "x", "-inul", path, unpack_dir
-  end
-end
-
-class LhaUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    magic_number.match?(/\A..-(lh0|lh1|lz4|lz5|lzs|lh\\40|lhd|lh2|lh3|lh4|lh5)-/n)
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system Formula["lha"].opt_bin/"lha", "xq2w=#{unpack_dir}", path
-  end
-end
-
-class GitUnpackStrategy < DirectoryUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    super && (path/".git").directory?
-  end
-end
-
-class SubversionUnpackStrategy < DirectoryUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    super && (path/".svn").directory?
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    safe_system "svn", "export", "--force", path, unpack_dir
-  end
-end
-
-class CvsUnpackStrategy < DirectoryUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    super && (path/"CVS").directory?
-  end
-end
-
-class MercurialUnpackStrategy < DirectoryUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    super && (path/".hg").directory?
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    with_env "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV["PATH"]) do
-      safe_system "hg", "--cwd", path, "archive", "--subrepos", "-y", "-t", "files", unpack_dir
-    end
-  end
-end
-
-class FossilUnpackStrategy < UnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    return false unless magic_number.match?(/\ASQLite format 3\000/n)
-
-    # Fossil database is made up of artifacts, so the `artifact` table must exist.
-    query = "select count(*) from sqlite_master where type = 'view' and name = 'artifact'"
-    Utils.popen_read("sqlite3", path, query).to_i == 1
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    args = if @ref_type && @ref
-      [@ref]
-    else
-      []
-    end
-
-    with_env "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV["PATH"]) do
-      safe_system "fossil", "open", path, *args, chdir: unpack_dir
-    end
-  end
-end
-
-class BazaarUnpackStrategy < DirectoryUnpackStrategy
-  def self.can_extract?(path:, magic_number:)
-    super && (path/".bzr").directory?
-  end
-
-  private
-
-  def extract_to_dir(unpack_dir, basename:, verbose:)
-    super
-
-    # The export command doesn't work on checkouts (see https://bugs.launchpad.net/bzr/+bug/897511).
-    FileUtils.rm_r unpack_dir/".bzr"
-  end
-end
+require "unpack_strategy/bazaar"
+require "unpack_strategy/bzip2"
+require "unpack_strategy/compress"
+require "unpack_strategy/cvs"
+require "unpack_strategy/directory"
+require "unpack_strategy/fossil"
+require "unpack_strategy/git"
+require "unpack_strategy/gzip"
+require "unpack_strategy/jar"
+require "unpack_strategy/lha"
+require "unpack_strategy/lua_rock"
+require "unpack_strategy/lzip"
+require "unpack_strategy/mercurial"
+require "unpack_strategy/microsoft_office_xml"
+require "unpack_strategy/p7zip"
+require "unpack_strategy/rar"
+require "unpack_strategy/subversion"
+require "unpack_strategy/tar"
+require "unpack_strategy/uncompressed"
+require "unpack_strategy/xar"
+require "unpack_strategy/xz"
+require "unpack_strategy/zip"

Library/Homebrew/unpack_strategy/bazaar.rb

@@ -0,0 +1,18 @@
+require_relative "directory"
+
+module UnpackStrategy
+  class Bazaar < Directory
+    def self.can_extract?(path:, magic_number:)
+      super && (path/".bzr").directory?
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      super
+
+      # The export command doesn't work on checkouts (see https://bugs.launchpad.net/bzr/+bug/897511).
+      FileUtils.rm_r unpack_dir/".bzr"
+    end
+  end
+end

Library/Homebrew/unpack_strategy/bzip2.rb

@@ -0,0 +1,17 @@
+module UnpackStrategy
+  class Bzip2
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\ABZh/n)
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      FileUtils.cp path, unpack_dir/basename, preserve: true
+      quiet_flags = verbose ? [] : ["-q"]
+      safe_system "bunzip2", *quiet_flags, unpack_dir/basename
+    end
+  end
+end

Library/Homebrew/unpack_strategy/compress.rb

@@ -0,0 +1,9 @@
+require_relative "tar"
+
+module UnpackStrategy
+  class Compress < Tar
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\A\037\235/n)
+    end
+  end
+end

Library/Homebrew/unpack_strategy/cvs.rb

@@ -0,0 +1,9 @@
+require_relative "directory"
+
+module UnpackStrategy
+  class Cvs < Directory
+    def self.can_extract?(path:, magic_number:)
+      super && (path/"CVS").directory?
+    end
+  end
+end

Library/Homebrew/unpack_strategy/directory.rb

@@ -0,0 +1,17 @@
+module UnpackStrategy
+  class Directory
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      path.directory?
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      path.children.each do |child|
+        FileUtils.copy_entry child, unpack_dir/child.basename, true, false
+      end
+    end
+  end
+end

Library/Homebrew/unpack_strategy/fossil.rb

@@ -0,0 +1,27 @@
+module UnpackStrategy
+  class Fossil
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      return false unless magic_number.match?(/\ASQLite format 3\000/n)
+
+      # Fossil database is made up of artifacts, so the `artifact` table must exist.
+      query = "select count(*) from sqlite_master where type = 'view' and name = 'artifact'"
+      Utils.popen_read("sqlite3", path, query).to_i == 1
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      args = if @ref_type && @ref
+        [@ref]
+      else
+        []
+      end
+
+      with_env "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV["PATH"]) do
+        safe_system "fossil", "open", path, *args, chdir: unpack_dir
+      end
+    end
+  end
+end

Library/Homebrew/unpack_strategy/git.rb

@@ -0,0 +1,9 @@
+require_relative "directory"
+
+module UnpackStrategy
+  class Git < Directory
+    def self.can_extract?(path:, magic_number:)
+      super && (path/".git").directory?
+    end
+  end
+end

Library/Homebrew/unpack_strategy/gzip.rb

@@ -0,0 +1,17 @@
+module UnpackStrategy
+  class Gzip
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\A\037\213/n)
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      FileUtils.cp path, unpack_dir/basename, preserve: true
+      quiet_flags = verbose ? [] : ["-q"]
+      safe_system "gunzip", *quiet_flags, "-N", unpack_dir/basename
+    end
+  end
+end

Library/Homebrew/unpack_strategy/jar.rb

@@ -0,0 +1,15 @@
+require_relative "uncompressed"
+
+module UnpackStrategy
+  class Jar < Uncompressed
+    def self.can_extract?(path:, magic_number:)
+      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+
+      # Check further if the ZIP is a JAR/WAR.
+      out, = Open3.capture3("zipinfo", "-1", path)
+      out.encode(Encoding::UTF_8, invalid: :replace)
+         .split("\n")
+         .include?("META-INF/MANIFEST.MF")
+    end
+  end
+end

Library/Homebrew/unpack_strategy/lha.rb

@@ -0,0 +1,19 @@
+module UnpackStrategy
+  class Lha
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\A..-(lh0|lh1|lz4|lz5|lzs|lh\\40|lhd|lh2|lh3|lh4|lh5)-/n)
+    end
+
+    def dependencies
+      @dependencies ||= [Formula["lha"]]
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system Formula["lha"].opt_bin/"lha", "xq2w=#{unpack_dir}", path
+    end
+  end
+end

Library/Homebrew/unpack_strategy/lua_rock.rb

@@ -0,0 +1,15 @@
+require_relative "uncompressed"
+
+module UnpackStrategy
+  class LuaRock < Uncompressed
+    def self.can_extract?(path:, magic_number:)
+      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+
+      # Check further if the ZIP is a LuaRocks package.
+      out, = Open3.capture3("zipinfo", "-1", path)
+      out.encode(Encoding::UTF_8, invalid: :replace)
+         .split("\n")
+         .any? { |line| line.match?(%r{\A[^/]+.rockspec\Z}) }
+    end
+  end
+end

Library/Homebrew/unpack_strategy/lzip.rb

@@ -0,0 +1,21 @@
+module UnpackStrategy
+  class Lzip
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\ALZIP/n)
+    end
+
+    def dependencies
+      @dependencies ||= [Formula["lzip"]]
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      FileUtils.cp path, unpack_dir/basename, preserve: true
+      quiet_flags = verbose ? [] : ["-q"]
+      safe_system Formula["lzip"].opt_bin/"lzip", "-d", *quiet_flags, unpack_dir/basename
+    end
+  end
+end

Library/Homebrew/unpack_strategy/mercurial.rb

@@ -0,0 +1,17 @@
+require_relative "directory"
+
+module UnpackStrategy
+  class Mercurial < Directory
+    def self.can_extract?(path:, magic_number:)
+      super && (path/".hg").directory?
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      with_env "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV["PATH"]) do
+        safe_system "hg", "--cwd", path, "archive", "--subrepos", "-y", "-t", "files", unpack_dir
+      end
+    end
+  end
+end

Library/Homebrew/unpack_strategy/microsoft_office_xml.rb

@@ -0,0 +1,13 @@
+require_relative "uncompressed"
+
+module UnpackStrategy
+  class MicrosoftOfficeXml < Uncompressed
+    def self.can_extract?(path:, magic_number:)
+      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+
+      # Check further if the ZIP is a Microsoft Office XML document.
+      magic_number.match?(/\APK\003\004/n) &&
+        magic_number.match?(%r{\A.{30}(\[Content_Types\]\.xml|_rels/\.rels)}n)
+    end
+  end
+end

Library/Homebrew/unpack_strategy/p7zip.rb

@@ -0,0 +1,19 @@
+module UnpackStrategy
+  class P7Zip
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\A7z\xBC\xAF\x27\x1C/n)
+    end
+
+    def dependencies
+      @dependencies ||= [Formula["p7zip"]]
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system "7zr", "x", "-y", "-bd", "-bso0", path, "-o#{unpack_dir}"
+    end
+  end
+end

Library/Homebrew/unpack_strategy/rar.rb

@@ -0,0 +1,19 @@
+module UnpackStrategy
+  class Rar
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\ARar!/n)
+    end
+
+    def dependencies
+      @dependencies ||= [Formula["unrar"]]
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system Formula["unrar"].opt_bin/"unrar", "x", "-inul", path, unpack_dir
+    end
+  end
+end

Library/Homebrew/unpack_strategy/subversion.rb

@@ -0,0 +1,15 @@
+require_relative "directory"
+
+module UnpackStrategy
+  class Subversion < Directory
+    def self.can_extract?(path:, magic_number:)
+      super && (path/".svn").directory?
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system "svn", "export", "--force", path, unpack_dir
+    end
+  end
+end

Library/Homebrew/unpack_strategy/tar.rb

@@ -0,0 +1,20 @@
+module UnpackStrategy
+  class Tar
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      return true if magic_number.match?(/\A.{257}ustar/n)
+
+      # Check if `tar` can list the contents, then it can also extract it.
+      IO.popen(["tar", "tf", path], err: File::NULL) do |stdout|
+        !stdout.read(1).nil?
+      end
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system "tar", "xf", path, "-C", unpack_dir
+    end
+  end
+end

Library/Homebrew/unpack_strategy/uncompressed.rb

@@ -0,0 +1,13 @@
+module UnpackStrategy
+  class Uncompressed
+    include UnpackStrategy
+
+    alias extract_nestedly extract
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      FileUtils.cp path, unpack_dir/basename, preserve: true, verbose: verbose
+    end
+  end
+end

Library/Homebrew/unpack_strategy/xar.rb

@@ -0,0 +1,15 @@
+module UnpackStrategy
+  class Xar
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\Axar!/n)
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      safe_system "xar", "-x", "-f", path, "-C", unpack_dir
+    end
+  end
+end

Library/Homebrew/unpack_strategy/xz.rb

@@ -0,0 +1,34 @@
+module UnpackStrategy
+  class Xz
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\A\xFD7zXZ\x00/n)
+    end
+
+    def dependencies
+      @dependencies ||= [Formula["xz"]]
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      FileUtils.cp path, unpack_dir/basename, preserve: true
+      quiet_flags = verbose ? [] : ["-q"]
+      safe_system Formula["xz"].opt_bin/"unxz", *quiet_flags, "-T0", unpack_dir/basename
+      extract_nested_tar(unpack_dir)
+    end
+
+    def extract_nested_tar(unpack_dir)
+      return unless DependencyCollector.tar_needs_xz_dependency?
+      return if (children = unpack_dir.children).count != 1
+      return if (tar = children.first).extname != ".tar"
+
+      Dir.mktmpdir do |tmpdir|
+        tmpdir = Pathname(tmpdir)
+        FileUtils.mv tar, tmpdir/tar.basename
+        Tar.new(tmpdir/tar.basename).extract(to: unpack_dir)
+      end
+    end
+  end
+end

Library/Homebrew/unpack_strategy/zip.rb

@@ -0,0 +1,16 @@
+module UnpackStrategy
+  class Zip
+    include UnpackStrategy
+
+    def self.can_extract?(path:, magic_number:)
+      magic_number.match?(/\APK(\003\004|\005\006)/n)
+    end
+
+    private
+
+    def extract_to_dir(unpack_dir, basename:, verbose:)
+      quiet_flags = verbose ? [] : ["-qq"]
+      safe_system "unzip", *quiet_flags, path, "-d", unpack_dir
+    end
+  end
+end