Add spec for nested directories.

Library/Homebrew/test/unpack_strategy_spec.rb

@@ -17,8 +17,13 @@ end
 
 describe UnpackStrategy do
   describe "#extract_nestedly" do
+    subject(:strategy) { described_class.detect(path) }
+
+    let(:unpack_dir) { mktmpdir }
+
+    context "when extracting a GZIP nested in a BZIP2" do
       let(:file_name) { "file" }
-    let(:nested_archive) {
+      let(:path) {
         dir = mktmpdir
 
         (dir/"file").write "This file was inside a GZIP inside a BZIP2."
@@ -27,8 +32,6 @@ describe UnpackStrategy do
 
         dir.children.first
       }
-    let(:unpack_dir) { mktmpdir }
-    subject(:strategy) { described_class.detect(nested_archive) }
 
       it "can extract nested archives" do
         strategy.extract_nestedly(to: unpack_dir)
@@ -36,6 +39,24 @@ describe UnpackStrategy do
         expect(File.read(unpack_dir/file_name)).to eq("This file was inside a GZIP inside a BZIP2.")
       end
     end
+
+    context "when extracting a directory with nested directories" do
+      let(:directories) { "A/B/C" }
+      let(:path) {
+        (mktmpdir/"file.tar").tap do |path|
+          mktmpdir do |dir|
+            (dir/directories).mkpath
+            system "tar", "-c", "-f", path, "-C", dir, "A/"
+          end
+        end
+      }
+
+      it "does not recurse into nested directories" do
+        strategy.extract_nestedly(to: unpack_dir)
+        expect(Pathname.glob(unpack_dir/"**/*")).to include unpack_dir/directories
+      end
+    end
+  end
 end
 
 describe UncompressedUnpackStrategy do