Testcontainers and API mocking with WireMock for C/C++ projects

Testcontainers has become one of the most popular tools for software integration testing. If you can put your system-under-test into a container, Docker compose cluster or a pod, this is what you're likely to use. If your target isn't ready, not containerizable or just too heavy for testing as is, you can always use API mocking like WireMock to mock your interfaces including REST API, gRPC, etc. But are these tools available to C/C++ developers? And the answer is YES!

In September 2023 I created Testcontainers for C/C++. This is not a standalone Testcontainers engine, but a C-style shared library adapter for native languages like C/C++, and also D, Lua, Swift, etc. It is a MVP SDK that can be later extended for the languages. The project is based on Testcontainers for Go which is one of the most powerful Testcontainers implementations. And yes happy to chat about how it does [and doesn’t] work under the hood.

The objective of this talk is to present the existing solution, find early adopters and get feedback from professional C/C++ developers who use modern C/C++. For me it has been 10 years since I used it professionally for Embedded and SCADA projects, so it would be awesome to get the community feedback on use-cases and priorities!

Transcript

1. Oleg Nenashev, WireMock Inc
4. Integration testing? 4 • Multiple technology stacks and toolchains • Many teams involved • Sacred knowledge • [Almost] always too late
8. Embedded Story 8 bit.ly/cpp_zurich_testcontainers_wiremock Slides are public!
9. > whoami @oleg_nenashev oleg-nenashev Dr. Nenashev / Mr. Jenkins Developer tools hacker Community builder & DevRel consultant #RussiansAgainstPutin #StandWithUkraine
10. Truly Russian C/C++ // my first project 10 tundrasolutions.ca/products/neftemer
11. @oleg_nenashev oleg-nenashev > whoami --c --cpp --embedded 11
14. 14 wiremock.org/docs/stubbing IF (request_url) THEN (response) * * it gets MUCH more complex WireMock Config JSON: Client library response request Client App Mock API Server HTTP/2
15. WireMock in Java 15 wiremock.org/docs/stubbing
16. WireMock in Java 16 wiremock.org/docs/stubbing
17. 17 WireMock 101 WireMock is a FOSS tool for building mock APIs Created in 2011 as a Java test library and CLI Available beyond Java, inc Rust or Golang You can can: • Create stable development environments • Isolate yourself from flakey 3rd parties • Simulate APIs that don't exist yet wiremock.org
18. WireMock Features 18 wiremock.org/docs
19. WireMock Ecosystem & Features 19 wiremock.org/docs
20. WireMock Cloud by WireMock Inc. 20 • WireMock creator is a co-founder of the Inc. • WireMock Cloud - SaaS for end-to-end API mocking • Private beta: K8s Edition for managed / on-premises • API co-development wiremock.io
21. Breaking down JSON files Using WireMock Cloud app.wiremock.cloud 21
22. 22 How about embedded? * we have customers in the space
23. IEEE Spectrum Research among members 23 https://spectrum.ieee.org/top-progra mming-languages-2021
24. 24 jetbrains.com/lp/ devecosystem-2021/embedded/
25. 25 Supported by WireMock and Testcontainers
28. github.com/testcontainers/testcontainers-c
31. 31 Build Unit tests Publish Reports Integration tests Publish Reports WAS
32. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Mocking at the API provider level (e.g. WireMock) 4. Mocking at the code level 32 Slow Fast Accu- rate Nope
33. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Mocking at the API provider level (e.g. WireMock) 4. Mocking at the code level 33 Slow Fast Nope Accu- rate
34. 34 Build Unit tests Publish Reports Integration tests Publish Reports NOW “Shift Left” Fast integrations tests are critical
36. Why containers? • Configuration Management • Fast provisioning • Clean environments • Disposability • Clustering
37. Docker in Embedded Prototypes, Dev Tools Test Infrastructures, CI/CD Docker Swarm Cluster on Raspberry Pi
38. Even simulator is not always an option http://blogs.synopsys.com/breakingthethreelaws 2014/04/the-secret-ninja-fu-for-higher-performa e-prototype-operation/ HAPS S96 Guess the price… Your device prototype is here
39. Docker • Popular container engine • Developer-friendly • Huge ecosystem • DockerHub and Container Registries • Docker Compose – multi-container apps • Universal image format (OCI) https://www.docker.com/
40. 40 https://testcontainers.com
42. Example - JUnit 5 42
44. Containers are not always slow! • On-demand image build • Caching Docker image builds • Suspending containers between tests • Graceful termination ◦ github.com/testcontainers/moby-ryuk 44 testcontainers.org
45. 45 SDKs testcontainers.org
46. Example - WireMock for Rust 46 docs.rs/wiremock/latest/wiremock LukeMathWalker/wiremock-rs Note: WireMock for Rust is maintained outside the WireMock GitHub organization
47. github.com/testcontainers/testcontainers-c
48. Testcontainers for C/C++ 48 Started by the WireMock Team in September 2023 We have Embedded/Automotive customers and users who need it Based on Testcontainers or Go WireMock module gh:testcontainers/testcontainers-c
49. Example - WireMock with C code 49 github.com/testcontainers/testcontain ers-c/tree/main/examples/wiremock • Testcontainers C is an experimental project • Feedback is welcome! • See more examples in the repository: CppUnit, OpenSCADA, etc.
50. 50 Supported by WireMock and Testcontainers
51. 51 Supported by WireMock and Testcontainers C/C++ Shared Lib Interface
52. Under the Hood 52 Testcontainers for Go C Adapter in Golang go build -buildmode=c-shared https://pkg.go.dev/cmd/cgo cgo C Header add-ons Header Files Test Code Your Project Test Executable
53. Using Testcontainers in C/C++ projects • Built with CMake • Any CMake-compatible package manager • FetchContent • CPM.make Coming soon: Conan, vcpkg 53 github.com/cpm-cmake/CPM.cmake
55. APIs are essential for Integration Testing 55 GROWTH IN WEB APIS SINCE 2005 Over 90% of developers use APIs. Skyrocket growth of APIs JANUARY 2006 JANUARY 2008 JANUARY 2010 JANUARY 2012 JANUARY 2014 JANUARY 2016 JANUARY 2018 MONTH The growth over time of the Programmable Web API API directory to more than 22,000 entries 22000 20000 18000 16000 14000 12000 10000 8000 6000 4000 2000 0 TOTAL API COUNT Programmable Web * Gartner Hype Cycle for APIs, 2022
56. APIs
57. 57 Source: https://medium.com/10-minutes-qa-story/api-testing-from-scratch-api-anatomy-f220856ce9b3
59. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Mocking at the API provider level (e.g. WireMock) 4. Mocking at the code level 59 Slow Fast Accu- rate Nope
61. 61 WireMock has an official Testcontainers module! testcontainers.com/modules/wiremock
63. WireMock for Go Testcontainers Module REST API Client Go test integrations go.wiremock.org 63 github.com/wiremock/wiremock-testcontainers-go
64. Powered by Testcontainers for C/C++
65. 65 Solutions page for C/C++: wiremock.org/docs/solutions/c_cpp Testcontainers module github.com/testcontainers/testcontainers-c /tree/main/modules/wiremock
67. Using WireMock with Testcontainers for C/C++ in Google Test github.com/oleg-nenashev/wiremock-googletest-demo
68. 68 WireMock for Google Test / C++ github.com/testcontainers/te stcontainers-c/tree/main/de mo/google-test
69. And then a test! 69 github.com/testcontainers/testcontainers-c/tree/main/demo/google-test
71. WireMock Public Roadmap 71 github.com/orgs/wiremock/projects/4
72. Testcontainers for C/C++ • Support for more features from Testcontainers for Go • C++ adapter with classes • Conan and Vcpkg distributions • Doxygen & docs 72 gh:testcontainers/testcontainers-c
75. Takeaways 75 • Shift left your integration testing • Mocking APIs and services, reducing external dependencies, containers • There are tools for that, including WireMock and Testcontainers • C/C++ is no exception from the trends
77. We need your feedback! 77 github.com/testcontainers/testcontainers-c/ …/CONTRIBUTING.md
78. Get Started wiremock.org/docs/solutions/embedded 78
80. It’s [always] a great time to contribute! testcontainers/testcontainers-c/../CONTRIBUTING.md wiremock.org/participate testcontainers.org/contributing 80
81. Credits to • All WireMock contributors • WireMock Inc. Team • All Testcontainers contributors and AtomicJar folks • All FOSS contributors 81
82. THANK YOU wiremock.org/testcontainers slack.wiremock.org slack.testcontainers.com github.com/shelajev/testcontainers-wiremock-demo wiremock.io 🏢
83. THANK YOU Contacts: E-mail: oleg@wiremock.org GitHub: oleg-nenashev Twitter: @oleg_nenashev QUESTIONS? 83