Answer Relevancy metric returns 1.0 even if `actual_output` is empty

[GeisaFaustino]

Describe the bug
Answer Relevancy metric returns 1.0 even if actual_output is empty

To Reproduce
Steps to reproduce the behavior:

from deepeval.metrics import AnswerRelevancyMetric
from deepeval.test_case import LLMTestCase

answer_relevancy = AnswerRelevancyMetric(model=MODEL)

test_case = LLMTestCase(
    input="What if these shoes don't fit?",
    actual_output="" # an empty output
)

answer_relevancy.measure(test_case)
print(f"Score:{answer_relevancy.score}\nReason: {answer_relevancy.reason}")

Score:1
Reason: The score is 1.00 because the response is fully relevant and directly addresses the input without any irrelevant statements. Great job!

Expected behavior
For an empty output, the expected behavior would be a score of 0.0 or close to it, as the output provides no relevant information to address the input.

[trevor-cai]

@GeisaFaustino thank you for reporting this. I will investigate and will reach out if I have any questions.

[trevor-cai]

@GeisaFaustino The fix is in review. Thanks again for reporting this and providing repro steps, I really appreciate it.