diff --git a/velox/functions/sparksql/tests/StringTest.cpp b/velox/functions/sparksql/tests/StringTest.cpp
index 900abcab3d9e..6042bf9bdbfc 100644
--- a/velox/functions/sparksql/tests/StringTest.cpp
+++ b/velox/functions/sparksql/tests/StringTest.cpp
@@ -21,6 +21,17 @@
 namespace facebook::velox::functions::sparksql::test {
 namespace {
 
+std::string generateRandomString(size_t length) {
+  const std::string chars =
+      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+  std::string randomString;
+  for (std::size_t i = 0; i < length; ++i) {
+    randomString += chars[folly::Random::rand32() % chars.size()];
+  }
+  return randomString;
+}
+
 class StringTest : public SparkFunctionBaseTest {
  protected:
   // This is a five codepoint sequence that renders as a single emoji.