Adds testing for w3c traceparent extraction.

Author: purple4reina

tests/test_tracing.py

@@ -191,6 +191,39 @@ def test_with_complete_datadog_trace_headers(self):
             expected_context,
         )
 
+    def test_with_w3c_trace_headers(self):
+        lambda_ctx = get_mock_context()
+        ctx, source, event_source = extract_dd_trace_context(
+            {
+                "headers": {
+                    "traceparent": "00-0000000000000000000000000000007b-0000000000000141-01",
+                }
+            },
+            lambda_ctx,
+        )
+        self.assertEqual(source, "event")
+        expected_context = Context(
+                trace_id=123,
+                span_id=321,
+                sampling_priority=1,
+                meta={"traceparent": "00-0000000000000000000000000000007b-0000000000000141-01"},
+        )
+        self.assertEqual(ctx, expected_context)
+        self.assertEqual(
+            get_dd_trace_context(),
+            Context(
+                trace_id=123,
+                span_id=fake_xray_header_value_parent_decimal,
+                sampling_priority=1,
+            ),
+        )
+        create_dd_dummy_metadata_subsegment(ctx, XraySubsegment.TRACE_KEY)
+        self.mock_send_segment.assert_called()
+        self.mock_send_segment.assert_called_with(
+            XraySubsegment.TRACE_KEY,
+            expected_context,
+        )
+
     def test_with_extractor_function(self):
         def extractor_foo(event, context):
             foo = event.get("foo", {})