_expect

Make approximate assertions as “expectations” on test results.

This module is designed to be used within test cases decorated with the @test decorator It allows you to log scores about a test case and optionally make assertions that log as “expectation” feedback to LangSmith.

Example usage:

from langsmith import expect, test

@test def test_output_semantically_close():

response = oai_client.chat.completions.create(

model=”gpt-3.5-turbo”, messages=[

{“role”: “system”, “content”: “You are a helpful assistant.”}, {“role”: “user”, “content”: “Say hello!”},

],

) response_txt = response.choices[0].message.content # Intended usage expect.embedding_distance(

prediction=response_txt, reference=”Hello!”,

).to_be_less_than(0.9)

# Score the test case matcher = expect.edit_distance(

prediction=response_txt, reference=”Hello!”,

) # Apply an assertion and log ‘expectation’ feedback to LangSmith matcher.to_be_less_than(1)

# You can also directly make assertions on values directly expect.value(response_txt).to_contain(“Hello!”) # Or using a custom check expect.value(response_txt).against(lambda x: “Hello” in x)

# You can even use this for basic metric logging within tests

expect.score(0.8) expect.score(0.7, key=”similarity”).to_be_greater_than(0.7)