Regression testing for chains in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the LangChain RegressionTester class.

LangChain

from langchain.testing import [1]

Drag options to blanks, or click blank then click option'

ARegressionTester

BChainTester

CChainRegression

DTestChain

Attempts:

3 left

💡 Hint

Common Mistakes

Using ChainTester instead of RegressionTester.

Trying to import from langchain.chains instead of langchain.testing.

The RegressionTester class is imported from langchain.testing to perform regression tests on chains.

2fill in blank

medium

Complete the code to create a RegressionTester instance for a chain named 'my_chain'.

LangChain

tester = RegressionTester(chain=[1])

Drag options to blanks, or click blank then click option'

Atest_chain

Bchain

CRegressionTester

Dmy_chain

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the class RegressionTester instead of the chain instance.

Using a variable name not defined like 'test_chain'.

The RegressionTester is initialized with the chain instance to test, here 'my_chain'.

3fill in blank

hard

Fix the error in the code to run regression tests and store results.

LangChain

results = tester.[1]()

Drag options to blanks, or click blank then click option'

Arun_tests

Bexecute

Crun_regression

Dtest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'execute' or 'test' which are not valid methods.

Using 'run_regression' which does not exist.

The correct method to run regression tests in RegressionTester is run_tests().

4fill in blank

hard

Fill both blanks to assert the test results contain no failures and print summary.

LangChain

assert results.[1] == 0
print(results.[2]())

Drag options to blanks, or click blank then click option'

Anum_failures

Bsummary

Cfail_count

Dreport

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fail_count' instead of 'num_failures'.

Using 'report()' instead of 'summary()'.

The results object has 'num_failures' attribute for failure count and 'summary()' method for a readable report.

5fill in blank

hard

Fill all three blanks to create a regression test with input, expected output, and run the test.

LangChain

test_input = [1]
expected_output = [2]
tester.add_test(input=test_input, expected=[3])

Drag options to blanks, or click blank then click option'

A{'text': 'Hello'}

B'Hello, world!'

Cexpected_output

D{'text': 'Hi'}

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the dictionary as expected output.

Using a literal string instead of the variable for expected parameter.

The input is a dictionary with text, expected output is a string, and the expected parameter uses the variable expected_output.

Practice

1.

What is the main purpose of regression testing for chains in Langchain?

easy

A. To add new features to the chain

B. To improve the speed of chain execution

C. To verify that chains still produce expected outputs after changes

D. To train the chain with new data

Solution

1. Step 1: Understand regression testing concept

   Regression testing is about checking if existing functionality still works after updates.

2. Step 2: Apply to chains context

   For chains, this means verifying outputs remain correct after code or data changes.

3. Final Answer:

   To verify that chains still produce expected outputs after changes -> Option C

4. Quick Check:

   Regression testing = verify outputs after changes [OK]

Hint: Regression testing checks output correctness after updates [OK]

Common Mistakes:

• Confusing regression testing with performance tuning
• Thinking regression testing adds new features
• Assuming regression testing trains models

2.

Which of the following is the correct way to run a regression test on a Langchain chain named my_chain with input {"text": "Hello"} and expected output {"result": "Hi"}?

easy

A. assert my_chain.invoke({"text": "Hello"}) == {"result": "Hi"}

B. my_chain.test({"text": "Hello"}, {"result": "Hi"})

C. my_chain.run({"text": "Hello"}) == {"result": "Hi"}

D. my_chain.regression_test({"text": "Hello"}, {"result": "Hi"})

Solution

1. Step 1: Identify correct method to run chain and compare output

   Langchain chains use invoke or run to get output; to test, use assert to compare.

2. Step 2: Check options for syntax correctness

   assert my_chain.invoke({"text": "Hello"}) == {"result": "Hi"} uses assert with invoke and compares to expected output correctly.

3. Final Answer:

   assert my_chain.invoke({"text": "Hello"}) == {"result": "Hi"} -> Option A

4. Quick Check:

   Use assert with invoke for regression test [OK]

Hint: Use assert with invoke to compare outputs in regression tests [OK]

Common Mistakes:

• Using non-existent methods like regression_test
• Comparing outputs without assert
• Confusing run and test methods

3.

Given the following code snippet, what will be the output of the regression test?

class EchoChain:
    def invoke(self, inputs):
        return {"echo": inputs["message"]}

my_chain = EchoChain()
input_data = {"message": "Test"}
expected_output = {"echo": "Test"}
result = my_chain.invoke(input_data) == expected_output
print(result)

medium

A. True

B. False

C. SyntaxError

D. RuntimeError

Solution

1. Step 1: Understand the EchoChain invoke method

   The method returns a dictionary with key "echo" and value from inputs["message"].

2. Step 2: Compare the returned output with expected output

   Input is {"message": "Test"}, so output is {"echo": "Test"}, which matches expected_output.

3. Final Answer:

   True -> Option A

4. Quick Check:

   Output matches expected = True [OK]

Hint: Check returned dict matches expected dict exactly [OK]

Common Mistakes:

• Assuming method returns input unchanged
• Confusing keys in output dictionary
• Expecting errors from correct code

4.

Identify the error in this regression test code snippet for a Langchain chain my_chain:

input_data = {"query": "Hello"}
expected = {"answer": "Hi"}
result = my_chain.invoke(input_data) == expected
print(result)

Assuming my_chain.invoke returns {"response": "Hi"}, what is the problem?

medium

A. The print statement syntax is wrong

B. The input_data dictionary is missing required keys

C. The invoke method is called incorrectly

D. The expected output keys do not match the actual output keys

Solution

1. Step 1: Compare expected and actual output keys

   Expected output has key "answer" but actual output has key "response".

2. Step 2: Understand impact on regression test

   Mismatch in keys causes the equality check to fail, so test result is False.

3. Final Answer:

   The expected output keys do not match the actual output keys -> Option D

4. Quick Check:

   Output keys mismatch causes test failure [OK]

Hint: Check keys in expected vs actual output carefully [OK]

Common Mistakes:

• Assuming input_data is wrong without checking
• Thinking invoke method call is incorrect
• Blaming print statement for logic errors

5.

You want to create a regression test suite for a Langchain chain that processes user questions and returns answers. Which approach best ensures your tests catch unintended changes in the chain's behavior?

hard

A. Test the chain with random inputs and manually check outputs each time

B. Store a set of input questions and their exact expected answers, then assert equality on each test run

C. Update expected answers after every chain change without verification

D. Only check that the chain runs without errors, ignoring output correctness

Solution

1. Step 1: Understand regression test goal

   Regression tests should detect if outputs change unexpectedly after updates.

2. Step 2: Evaluate options for reliability

   Store a set of input questions and their exact expected answers, then assert equality on each test run uses fixed input-output pairs and asserts equality, which reliably detects changes.

3. Final Answer:

   Store a set of input questions and their exact expected answers, then assert equality on each test run -> Option B

4. Quick Check:

   Fixed input-output pairs catch unintended changes [OK]

Hint: Use fixed input-output pairs for reliable regression tests [OK]

Common Mistakes:

• Ignoring output correctness in tests
• Blindly updating expected outputs
• Relying on manual checks only