fix sinatra tests

spec/ddtrace/contrib/sinatra/tracer_spec.rb

@@ -294,9 +294,7 @@
       end
     end
 
-    context 'with distributed tracing' do
-      let(:options) { super().merge(distributed_tracing: true) }
-
+    context 'with distributed tracing default' do
       context 'and a simple request is made' do
         include_context 'app with simple route'
 
@@ -324,6 +322,36 @@
       end
     end
 
+    context 'with distributed tracing disabled' do
+      let(:options) { super().merge(distributed_tracing: false) }
+
+      context 'and a simple request is made' do
+        include_context 'app with simple route'
+
+        subject(:response) { get '/', query_string, headers }
+        let(:query_string) { {} }
+        let(:headers) { {} }
+
+        context 'without distributed tracing headers' do
+          let(:headers) do
+            {
+              'HTTP_X_DATADOG_TRACE_ID' => '1',
+              'HTTP_X_DATADOG_PARENT_ID' => '2',
+              'HTTP_X_DATADOG_SAMPLING_PRIORITY' => Datadog::Ext::Priority::USER_KEEP.to_s
+            }
+          end
+
+          it do
+            is_expected.to be_ok
+            expect(spans).to have(1).items
+            expect(span.trace_id).to_not eq(1)
+            expect(span.parent_id).to_not eq(2)
+            expect(span.get_metric(Datadog::Ext::DistributedTracing::SAMPLING_PRIORITY_KEY)).to_not eq(2.0)
+          end
+        end
+      end
+    end
+
     context 'with header tags' do
       let(:options) { super().merge(headers: { request: request_headers, response: response_headers }) }
       let(:request_headers) { [] }