Perform request spec (#6446)

* Added #link_header spec

* Added #perform_request spec

spec/services/fetch_atom_service_spec.rb

@@ -21,4 +21,43 @@ RSpec.describe FetchAtomService do
       it { expect(target.send(:link_header).links[0].href).to eq 'http://example.com/foo' }
     end
   end
+
+  describe '#perform_request' do
+    let(:url) { 'http://example.com' }
+    context 'Check method result' do
+      before do
+        WebMock.stub_request(:get, url).to_return(status: 200, body: '', headers: {})
+        @target = FetchAtomService.new
+        @target.instance_variable_set('@url', url)
+      end
+
+      it 'HTTP::Response instance is returned and set to @response' do
+        expect(@target.send(:perform_request).status.to_s).to eq '200 OK'
+        expect(@target.instance_variable_get('@response')).to be_instance_of HTTP::Response
+      end
+    end
+
+    context 'check passed parameters to Request' do
+      before do
+        @target = FetchAtomService.new
+        @target.instance_variable_set('@url', url)
+        @target.instance_variable_set('@unsupported_activity', unsupported_activity)
+        allow(Request).to receive(:new).with(:get, url)
+        expect(Request).to receive_message_chain(:new, :add_headers).with('Accept' => accept)
+        allow(Request).to receive_message_chain(:new, :add_headers, :perform).with(no_args)
+      end
+
+      context '@unsupported_activity is true' do
+        let(:unsupported_activity) { true }
+        let(:accept) { 'text/html' }
+        it { @target.send(:perform_request) }
+      end
+
+      context '@unsupported_activity is false' do
+        let(:unsupported_activity) { false }
+        let(:accept) { 'application/activity+json, application/ld+json, application/atom+xml, text/html' }
+        it { @target.send(:perform_request) }
+      end
+    end
+  end
 end