fix: type check event before treating it as a dict (#233)

* fix: type check event before treating it as a dict

* fix: Use doublequotes for binary string

Author: astuyve

datadog_lambda/tracing.py

@@ -334,7 +334,7 @@ def extract_dd_trace_context(event, lambda_context, extractor=None):
             parent_id,
             sampling_priority,
         ) = extract_context_custom_extractor(extractor, event, lambda_context)
-    elif "headers" in event:
+    elif isinstance(event, (list, dict)) and "headers" in event:
         (
             trace_id,
             parent_id,

tests/test_tracing.py

@@ -104,6 +104,28 @@ def test_without_datadog_trace_headers(self):
             {},
         )
 
+    def test_with_non_object_event(self):
+        lambda_ctx = get_mock_context()
+        ctx, source = extract_dd_trace_context(b"", lambda_ctx)
+        self.assertEqual(source, "xray")
+        self.assertDictEqual(
+            ctx,
+            {
+                "trace-id": fake_xray_header_value_root_decimal,
+                "parent-id": fake_xray_header_value_parent_decimal,
+                "sampling-priority": "2",
+            },
+        )
+        self.assertDictEqual(
+            get_dd_trace_context(),
+            {
+                TraceHeader.TRACE_ID: fake_xray_header_value_root_decimal,
+                TraceHeader.PARENT_ID: fake_xray_header_value_parent_decimal,
+                TraceHeader.SAMPLING_PRIORITY: "2",
+            },
+            {},
+        )
+
     def test_with_incomplete_datadog_trace_headers(self):
         lambda_ctx = get_mock_context()
         ctx, source = extract_dd_trace_context(