add assertTraceResponseHeaderMatchesSpan method (#2159)

* add assertTraceResponseHeaderMatchesSpan method

* fix lint

Co-authored-by: Diego Hurtado <[email protected]>

Author: alrex

tests/util/src/opentelemetry/test/wsgitestutil.py

@@ -15,6 +15,7 @@
 import io
 import wsgiref.util as wsgiref_util
 
+from opentelemetry import trace
 from opentelemetry.test.spantestutil import SpanTestBase
 
 
@@ -37,3 +38,19 @@ def start_response(self, status, response_headers, exc_info=None):
         self.response_headers = response_headers
         self.exc_info = exc_info
         return self.write
+
+    def assertTraceResponseHeaderMatchesSpan(
+        self, headers, span
+    ):  # pylint: disable=invalid-name
+        self.assertIn("traceresponse", headers)
+        self.assertEqual(
+            headers["access-control-expose-headers"],
+            "traceresponse",
+        )
+
+        trace_id = trace.format_trace_id(span.get_span_context().trace_id)
+        span_id = trace.format_span_id(span.get_span_context().span_id)
+        self.assertEqual(
+            f"00-{trace_id}-{span_id}-01",
+            headers["traceresponse"],
+        )