Support zstd decompression

docs/README.md

@@ -123,11 +123,16 @@ If you explicitly set `Accept-Encoding`, there be dragons:
   `Net::HTTP` will automatically decompress it, and will omit `Content-Encoding`
   from your `HTTParty::Response` headers.
 
-* For encodings `br` (Brotli) or `compress` (LZW), HTTParty will automatically
-  decompress if you include the `brotli` or `ruby-lzws` gems respectively into your project.
+* For the following encodings, HTTParty will automatically decompress them if you include
+  the required gem into your project. Similar to above, if decompression succeeds,
+  `Content-Encoding` will be omitted from your `HTTParty::Response` headers.
   **Warning:** Support for these encodings is experimental and not fully battle-tested.
-  Similar to above, if decompression succeeds, `Content-Encoding` will be omitted
-  from your `HTTParty::Response` headers.
+
+  | Encoding | Required Gem |
+  | --- | --- |
+  | `br` (Brotli)      | [brotli](https://rubygems.org/gems/brotli) |
+  | `compress` (LZW)   | [ruby-lzws](https://rubygems.org/gems/ruby-lzws) |
+  | `zstd` (Zstandard) | [zstd-ruby](https://rubygems.org/gems/zstd-ruby) |
 
 * For other encodings, `HTTParty::Response#body` will return the raw uncompressed byte string,
   and you'll need to inspect the `Content-Encoding` response header and decompress it yourself.
@@ -147,7 +152,8 @@ JSON.parse(res.body) # safe
 
 require 'brotli'
 require 'lzws'
-res = HTTParty.get('https://example.com/test.json', headers: { 'Accept-Encoding' => 'br,compress' })
+require 'zstd-ruby'
+res = HTTParty.get('https://example.com/test.json', headers: { 'Accept-Encoding' => 'br,compress,zstd' })
 JSON.parse(res.body)
 
 

lib/httparty/decompressor.rb

@@ -17,7 +17,8 @@ class Decompressor
       'none'     => :none,
       'identity' => :none,
       'br'       => :brotli,
-      'compress' => :lzw
+      'compress' => :lzw,
+      'zstd'     => :zstd
     }.freeze
 
     # The response body of the request
@@ -88,5 +89,14 @@ def lzw
         nil
       end
     end
+
+    def zstd
+      return nil unless defined?(::Zstd)
+      begin
+        ::Zstd.decompress(body)
+      rescue StandardError
+        nil
+      end
+    end
   end
 end

spec/httparty/decompressor_spec.rb

@@ -131,5 +131,33 @@
         end
       end
     end
+
+    context 'when encoding is "zstd"' do
+      let(:encoding) { 'zstd' }
+
+      context 'when zstd-ruby gem not included' do
+        it_behaves_like 'returns nil'
+      end
+
+      context 'when zstd-ruby included' do
+        before do
+          dbl = double('Zstd')
+          expect(dbl).to receive(:decompress).with('body').and_return('foobar')
+          stub_const('Zstd', dbl)
+        end
+
+        it { expect(subject).to eq 'foobar' }
+      end
+
+      context 'when zstd raises error' do
+        before do
+          dbl = double('Zstd')
+          expect(dbl).to receive(:decompress).with('body') { raise RuntimeError.new('zstd error') }
+          stub_const('Zstd', dbl)
+        end
+
+        it { expect(subject).to eq nil }
+      end
+    end
   end
 end