Add test

Library/Homebrew/test/download_strategies_spec.rb

@@ -200,6 +200,17 @@ describe GitDownloadStrategy do
   end
 end
 
+describe CurlDownloadStrategy do
+  subject { described_class.new(name, resource) }
+  let(:name) { "foo" }
+  let(:url) { "http://example.com/foo.tar.gz" }
+  let(:resource) { double(Resource, url: url, mirrors: [], specs: {user: "download:123456"}, version: nil) }
+
+  it "parses the opts and sets the corresponding args" do
+    expect(subject.send(:_curl_opts)).to eq(["--user","download:123456"])
+  end
+end
+
 describe DownloadStrategyDetector do
   describe "::detect" do
     subject { described_class.detect(url) }