Exceptional behavior tests (EBTs) are crucial in software development
for verifying that code correctly handles unwanted events and throws
appropriate exceptions. However, prior research has shown that
developers often prioritize testing "happy paths", i.e., paths without
unwanted events, over exceptional scenarios. We present exLong, a tool
that automatically generates EBTs to address this gap.  exLong
leverages a large language model (LLM) fine-tuned from CodeLlama and
incorporates reasoning about exception-throwing traces, conditional
expressions that guard throw statements, and non-exceptional behavior
tests that execute similar traces. Our demonstration video illustrates
how exLong can effectively assist developers in creating comprehensive
EBTs for their project (available at https://youtu.be/Jro8kMgplZk).