Testing in go

Techniques for testing in go

Transcript

1. TESTING AND OTHER TOOLS Scott Johnson - Weave scott@getweave.com @t_itchy itchy
3. Why?
4. • Works • Regression • Design
5. Design
6. Our App • Send appointment reminder text messages • Find patients with scheduled appointments 1,7 or 28 days out • Send a text message with appointment reminder
7. Unit Testing • Any file that ends in _test.go • Same package • Include testing • func starts with Test
10. TDD Zone • Green • Red • Green • Refactor
11. Table Driven Tests — Dave Cheney
12. Begin with the end in mind
13. Stay in the zone — Karl Seguin • The difference between a method that's easy to test and not is often a matter of whether you are passing interfaces (good) or concrete types (bad) • Since functions are first class types in Go, functions can also be passed around to decouple implementations
14. SOLID — Uncle Bob • Single Responsibility • Open/Closed • Liskov substitution • Interface (narrow) • Dependency Inversion
15. Works
16. Works
17. Works
18. Works
19. Works
20. Works
21. Integration/Functional testing
22. net/http/httptest • ResponseRecorder • Server
25. Dependency Inversion vs. Encapsulation Why would you make me pick a plug every time I use this?
26. Mocking/Stubbing/Doubles • Sometimes passing interfaces or injecting dependencies is impractical and can even damage our application design
27. • http://godoc.org/github.com/qur/withmock • install Bazaar • go get github.com/qur/withmock • go get github.com/qur/withmock/mocktest • $> withmock go test • $> mocktest
31. Time • http://stackoverflow.com/questions/18970265/is-there-an-easy- way-to-stub-out-time-now-globally-in-golang-during-test
32. Time Controller • Create struct containing time • Default time is system time
33. Time Controller • Requires injection into method
34. Time Controller
35. Coverage • go test -coverprofile=coverage.out • go tool cover -html=coverage.out
36. Benchmarks • funcs start with Benchmark • Pass *testing.B • b.N is calculated by the compiler to insure that the 
 loop runs for at least 1 second • go test -bench=.
37. Traps — Dave Cheney • Don’t change the value of the func inside the for loop • Don’t pass b.N as a param • Always store results in a package level var so it is not skipped 
 by compiler optimizations
38. More… • $> go help test • $> go help testflag • $> go test run=regexp
39. Profiling Go Programs • When CPU profiling is enabled, the Go program stops about 100 times per second and records a sample consisting of the program counters on the currently executing goroutine's stack. • With go test lib you can use • -cpuprofile • -memprofile
40. But not in OS X • https://code.google.com/p/go/issues/detail?id=6047
 
 Multithreaded CPU profiles do not work on OS X, but worse they give little indication that they are broken.
41. Race Detector • When the -race command- line flag is set, the compiler instruments all memory accesses with code that records when and how the memory was accessed, while the runtime library watches for unsynchronized accesses to shared variables. When such "racy" behavior is detected, a warning is printed
42. • http://dave.cheney.net/2013/06/09/writing-table-driven-tests-in-go • http://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go • https://github.com/davecheney/fib • http://blog.golang.org/cover • http://blog.golang.org/profiling-go-programs • http://justsomething.co/the-34-most-hilarious-pinterest-fails-ever/ • kexchange.com/questions/4499/could-the-crashed-mars-express-lander-be-imaged- by-the-mro-orbiter • http://uafcornerstone.net/wp-content/uploads/2012/07/Red-Green- Regatta-2011-032.jpg • http://news.3yen.com/wp-content/images/Admiral-Ackbar-Itzza-trap.jpg • http://www.poetryfoundation.org/harriet/wp-content/uploads/ 2013/03/4-1-13_Madrid.jpg • http://graphics8.nytimes.com/images/2011/10/11/sports/baseball/11sausages-pic/ 11sausages-pic-articleLarge.jpg