Add support to Shakapacker

Shakapacker is the official, actively maintained successor to Webpacker.

Shakapacker v7 changed the spelling of `Webpacker` to `Shakapacker` in
the entire project, but still provided backward compatibility for
`Webpacker` spelling.

v8 dropped the deprecated spelling

This commit also:
- Checks if `Shakapacker` is defined; if not, it falls back on
  `Webpacker`.
- Uses the scope resolution operator to resolve at top-level
  scope
- Checks `protocol` instead of `https?` because the former is available
  from Webpacker 3 and the latter is not available anymore in
  Shakapacker >= 8

Refs:
- shakacode/shakapacker#414
- shakacode/shakapacker#429
- shakacode/shakapacker#486

Close #156

lib/inline_svg/webpack_asset_finder.rb

@@ -6,22 +6,31 @@ def self.find_asset(filename)
 
  def initialize(filename)
  @filename = filename
- manifest_lookup = Webpacker.manifest.lookup(@filename)
+ manifest_lookup = wrapper.manifest.lookup(@filename)
  @asset_path = manifest_lookup.present? ? URI(manifest_lookup).path : ""
  end
 
  def pathname
  return if @asset_path.blank?
 
- if Webpacker.dev_server.running?
+ if wrapper.dev_server.running?
  dev_server_asset(@asset_path)
- elsif Webpacker.config.public_path.present?
- File.join(Webpacker.config.public_path, @asset_path)
+ elsif wrapper.config.public_path.present?
+ File.join(wrapper.config.public_path, @asset_path)
  end
  end
 
  private
 
+ def wrapper
+ @wrapper ||=
+ if defined?(::Shakapacker)
+ ::Shakapacker
+ else
+ ::Webpacker
+ end
+ end
+
  def dev_server_asset(file_path)
  asset = fetch_from_dev_server(file_path)
 
@@ -38,8 +47,8 @@ def dev_server_asset(file_path)
  end
 
  def fetch_from_dev_server(file_path)
- http = Net::HTTP.new(Webpacker.dev_server.host, Webpacker.dev_server.port)
- http.use_ssl = Webpacker.dev_server.https?
+ http = Net::HTTP.new(wrapper.dev_server.host, wrapper.dev_server.port)
+ http.use_ssl = wrapper.dev_server.protocol == "https"
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE
 
  http.request(Net::HTTP::Get.new(file_path)).body

spec/webpack_asset_finder_spec.rb

@@ -10,4 +10,14 @@
  expect(described_class.find_asset('some-file').pathname).to be_nil
  end
  end
+
+ context "when Shakapacker is defined" do
+ it "uses the new spelling" do
+ stub_const('Rails', double('Rails').as_null_object)
+ stub_const('Shakapacker', double('Shakapacker').as_null_object)
+ expect(::Shakapacker.manifest).to receive(:lookup).with('some-file').and_return(nil)
+
+ expect(described_class.find_asset('some-file').pathname).to be_nil
+ end
+ end
 end