From 0a38d039a1685e67a02860746371f99dcc3ef12c Mon Sep 17 00:00:00 2001
From: ben-gawel <167240029+ben-gawel@users.noreply.github.com>
Date: Fri, 31 Oct 2025 16:03:39 -0400
Subject: [PATCH] SERVER-112812 Fix invalid access issue when
 TestData.enableOTELTracing is enabled (#43176)

GitOrigin-RevId: 93124538b5a759a9f8c37176462d70c76f79b302
---
 src/mongo/otel/traces/bson_text_map_carrier.cpp      | 2 +-
 src/mongo/otel/traces/bson_text_map_carrier.h        | 3 +++
 src/mongo/otel/traces/bson_text_map_carrier_test.cpp | 4 ++--
 src/mongo/shell/utils.js                             | 7 +++----
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/mongo/otel/traces/bson_text_map_carrier.cpp b/src/mongo/otel/traces/bson_text_map_carrier.cpp
index 34518fc66f9..e96c6bdbd8e 100644
--- a/src/mongo/otel/traces/bson_text_map_carrier.cpp
+++ b/src/mongo/otel/traces/bson_text_map_carrier.cpp
@@ -47,7 +47,7 @@ BSONTextMapCarrier::BSONTextMapCarrier(const BSONObj& bson) {
 OtelStringView BSONTextMapCarrier::Get(OtelStringView key) const noexcept {
     auto it = _values.find(key);
     if (it == _values.end()) {
-        return {};
+        return kMissingKeyReturnValue;
     }
     return it->second;
 }
diff --git a/src/mongo/otel/traces/bson_text_map_carrier.h b/src/mongo/otel/traces/bson_text_map_carrier.h
index 21364006d74..0ef0163b0cb 100644
--- a/src/mongo/otel/traces/bson_text_map_carrier.h
+++ b/src/mongo/otel/traces/bson_text_map_carrier.h
@@ -39,6 +39,9 @@ namespace mongo {
 namespace otel {
 namespace traces {
 
+// TODO SERVER-112886: Once this ticket is resolved this should be changed back to an empty string.
+constexpr OtelStringView kMissingKeyReturnValue = " ";
+
 using opentelemetry::nostd::function_ref;
 
 /**
diff --git a/src/mongo/otel/traces/bson_text_map_carrier_test.cpp b/src/mongo/otel/traces/bson_text_map_carrier_test.cpp
index c1712056051..5a9b8207865 100644
--- a/src/mongo/otel/traces/bson_text_map_carrier_test.cpp
+++ b/src/mongo/otel/traces/bson_text_map_carrier_test.cpp
@@ -63,7 +63,7 @@ TEST(BSONTextMapCarrier, GetExistingKey) {
 
 TEST(BSONTextMapCarrier, GetMissingKey) {
     BSONTextMapCarrier carrier;
-    ASSERT_EQ(carrier.Get(keyA), "");
+    ASSERT_EQ(carrier.Get(keyA), kMissingKeyReturnValue);
 }
 
 TEST(BSONTextMapCarrier, SetExistingKey) {
@@ -127,7 +127,7 @@ TEST(BSONTextMapCarrier, NonStringFieldsIgnored) {
     ASSERT_EQ(keys.size(), 1);
     ASSERT_TRUE(keys.contains(keyA));
     ASSERT_EQ(carrier.Get(keyA), valueA);
-    ASSERT_EQ(carrier.Get("uuid"), "");
+    ASSERT_EQ(carrier.Get("uuid"), kMissingKeyReturnValue);
 }
 
 }  // namespace
diff --git a/src/mongo/shell/utils.js b/src/mongo/shell/utils.js
index 2e2bd493983..99bfd634d4d 100644
--- a/src/mongo/shell/utils.js
+++ b/src/mongo/shell/utils.js
@@ -353,10 +353,9 @@ let _jsTestOptions = {};
 
 function jsTestOptions() {
     if (TestData) {
-        // TODO (SERVER-112812): Enable OpenTelemetry tracing.
-        // const isMultiversion =
-        // TestData.useRandomBinVersionsWithinReplicaSet || TestData.mixedBinVersions || TestData.mongosBinVersion;
-        const enableOTELTracing = false; //TestData.enableOTELTracing ?? !isMultiversion;
+        const isMultiversion =
+            TestData.useRandomBinVersionsWithinReplicaSet || TestData.mixedBinVersions || TestData.mongosBinVersion;
+        const enableOTELTracing = TestData.enableOTELTracing ?? !isMultiversion;
 
         return Object.merge(_jsTestOptions, {
             // Test commands should be enabled by default if no enableTestCommands were present in