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Version: 2.0.0

Testing Guide 🧪

In this blog, we will learn how test bench of keploy works and how you can contribute to keploy's code coverage.

Keploy test Keploy?

  • Keploy's test bench is built on the principle that Keploy can test itself, operating in two distinct modes: RECORD and TEST. Each mode activates different sections of the codebase, with some overlap between the two. These modes can be executed concurrently to enhance testing efficiency.

  • keployR & keployT are similar binaries just the name is different for readability.

  • For example, if you have recorded tests and mocks for a Go + MongoDB application keploy/samples-go/gin-mongo, the test bench allows you to run Keploy in test mode (keployT) from within Keploy in record mode (keployR) using the following pseudo command: keployR record -c "keployT test -c ./gin-mongo-app. This command initiates Keploy in record mode, which in turn launches Keploy in test mode to run the application. As keployT executes the test sets, it simulates API calls for each test case. These simulated API calls are then recorded as tests by keployR, along with any external calls from the application being captured as mocks. Meanwhile, keployT generates a final report of the test runs. This approach allows for the simultaneous execution of both Keploy's record and test flows.

  • One significant benefit of this method is that it eliminates the need to set up external dependencies in the CI pipeline for testing. KeployT acts as a virtual database, with its calls being recorded by keployR, streamlining the testing process.

Running Guide

This guide includes the recording and testing of tests and mocks with the help of keploy test-bench.


  • Get the latest version of keploy by following this. And rename the binary to keployR (released) using sudo mv usr/local/bin/keploy /usr/local/bin/keployR

  • Get the current version of keploy by building the binary with current changes using

go build -tags=viper_bind_struct -cover -o keployB . && sudo mv keployB /usr/local/bin/keployB
  • You will now have built and released binary of keploy as keployB and keployR respectively.

  • Take any application, I've tested for the gin-mongo sample app so you can take that one as of now. And record test some cases, make at least two sessions of recording. Use the below command to record tests and mocks via the released binary of keploy

sudo -E env PATH=$PATH keployR record -c "<running cmd of gin-mongo>"
  • You will also be requiring pilot to assert tests and prepare mocks for assertion, you can get the latest pilot using:
curl --silent -o pilot --location "" &&
sudo chmod a+x pilot && sudo mkdir -p /usr/local/bin && sudo mv pilot /usr/local/bin
  • To enable testing mode of keploy, --enableTesting flag is required.

Why both released and built keploy binaries?

Note: Here keployR is released binary and keployB is built binary. The idea is that there will be two cases:

  1. The latest released version of keploy will be used for recording the tests & mocks using and built version of keploy will be used for testing. i.e. keployR record -c "keployB test -c ./gin-mongo-app.

  2. The latest released version of keploy will be used for testing and built version of keploy will be used for recording tests & mocks. i.e. keployB record -c "keployR test -c ./gin-mongo-app.

These two scenarios are designed to ensure the detection of changes, including any potential breaking changes or adjustments that may affect backward compatibility.

Recording and testing of tests and mocks via test-bench

Right now, in this guide i am only showing the first scenario, to run the second scenario you just need to replace the binaries as mentioned in the 4th step.

Recording Phase 🎥

  1. Since you now already have some recorded tests and mocks of gin-mongo application, let's call it pre-recorded tests.

  2. To record tests and mocks via test-bench, you need to run this command to record test cases (for each test-set you have to run this command):

sudo -E env PATH=$PATH keployR record -c "sudo -E env PATH=$PATH keployB test -c '<binary of gin-mongo>' --proxyPort 56789 --dnsPort 46789  --delay=<delay> --testsets <test-set-id> --configPath '<config-path>' --path '<path-to-pre-recorded-tests>' --enableTesting --generateGithubActions=false" --path "./test-bench/" --proxyPort=36789 --dnsPort 26789 --configPath '<config-path>' --enableTesting --generateGithubActions=false
  1. This above command will generate new tests and mocks from your existing pre-recorded tests and mocks.

  2. For second scenario, you just need to use keployB for recording and keployR for testing.

Testing Phase 🧪

  1. Assert the tests

With this step, your tests undergo validation as the pilot compares HTTP requests and responses from both the pre-recorded and test-bench-recorded tests. This comparison considers noisy fields, utilizing the configuration file for accuracy.

pilot -test-assert -preRecPath <path-to-pre-recorded-tests> -testBenchPath ./test-bench -configPath <path-to-config-file>
  1. Prepare mock assertions

By feeding the mocks from the newly recorded test cases into the pre-recorded ones (and vice versa), and observing if the results match those obtained with the original mocks, you can confirm the validity of the new mocks. This reciprocal testing ensures the integrity and reliability of the newly generated test data.

However, Keploy uniquely incorporates the timestamps of each request and response in the tests (ingress) and compares these with the timestamps in the mocks (egress). This method significantly reduces the chances of mismatches by selectively retaining only the mocks that come under the request and response time of the test case.

Directly incorporating mocks recorded through the testing approach into pre-recorded test cases could lead to failures, as these were initially recorded at much earlier times. To overcome this issue, we swap the timestamps of the request and response between the pre-recorded and newly recorded test cases. This adjustment ensures that the mocks are compatible and can be effectively utilized without disrupting the natural workflow of Keploy. Thus, this strategy allows us to use the mocks correctly and ensures the accuracy of our test validations.

pilot -mock-assert -preRecPath <path-to-pre-recorded-tests> -testBenchPath ./test-bench -configPath <path-to-config-file>
  1. Do the actual mock assertion

You just need to run test mode for both the pre-recorded and newly test-bench-recorded tests and mocks via the released binary of keploy.

  • For pre-recorded:
sudo -E env PATH=$PATH keployR test -c "<app running command>" --delay <app delay> --path "<path-to-pre-recorded-tests>" --generateGithubActions=false
  • For test-bench-recorded:
sudo -E env PATH=$PATH keployR test -c "<app running command>" --delay <app delay> --path "./test-bench" --generateGithubActions=false

If both scenarios yield a "passed" result, it signifies that this approach mirrors the standard recording and testing process via Keploy. In that case, you're all set to proceed, and your tests and mocks are considered legitimate.

Running the setup in CI (Github Actions)

  • Implementing this setup in CI will enhance Keploy's testing by incorporating various sample applications with different supported dependencies. This comprehensive testing will thoroughly assess Keploy's major components, including the proxy and parsers.

  • To achieve this, you'll need to add two workflows for each sample application, covering both recording and testing scenarios.

  • You can refer to this setup for guidance.

Limitations ⚠️

  • Port Configuration: The ports for Keploy Record (keployR) and Keploy Test (keployT) need to be hardcoded. You can't change the ports and run this entire setup properly.
  • Sequential Test Sets: Only one test set can be run at a time.
  • Limited Environment Support: This feature is currently available only for native binary environments and not for Docker environments.
  • Recording Delay: After the test runs, there is a waiting period of 1 second to ensure proper recording of test cases. (related to implementation)
  • Process Filtering: Internally, Keploy Record (keployR) should handle only application-related calls and not Keploy Test (keployT) related calls. To achieve this, keployT waits for keployR to retrieve the PID before starting the test run. This ensures that keployR can filter out keployT related calls based on the PID. (related to implementation)
  • As of now, running this setup on WSL is not handled.
  • Don't rename the test-sets or test-cases while running this setup.