lesson5.slide

Testing, CGo and tools
Lesson 5
30 May 2024
Tags: golang, go

Jakub Čajka <jcajka@redhat.com>
Red Hat, Inc.
https://github.com/RedHatOfficial/GoCourse
@RedHat

* Sources
- [[https://github.com/RedHatOfficial/GoCourse]]
.image ./common/qr_address.png

* Gophers
#The Go gopher was designed by Renee French. (http://reneefrench.blogspot.com/)
#Source https://golang.org/doc/gopher/fiveyears.jpg
#The design and this image is licensed under the Creative Commons 3.0 Attributions license.
.image ./common/fiveyears.jpg _ 900

* Testing and Benchmarking in Go
- Unit test "framework" integral to the Go command
- `go` `test`
- (Micro)Benchmark "framework" part of it too
- `go` `test` `-bench` `.`
- package `testing`
- code needs to be "vetable", pass `go` `vet` check

* Tests
- in `_test.go` files
- all `Test*(t` `*testing.T)` functions get executed

* Test main
- `func` `TestMain(m` `*testing.M)`
- `m.Run`
- provides ability to do setup, passing CLI flags,...
- execute tests that don't fit the basic framework, etc.
- checkout misc/cgo GC tests

* Benchmarks
- in `_test.go` files
- all `Benchmark*(b` `*testing.B)` functions get executed
- can benchmark not only performance(`-bench`), but memory usage(`-benchmem`)

* Assertions in Go
- `assert` is not keyword in Go
- but assert-like functions and methods exist
- third party libraries

* Assertions in Go (factorial)
.code testing/assertions/assertions1/factorial.go

* Assertions in Go (factorial)
.code testing/assertions/assertions1/factorial_test.go

* More assertions-like functions

.code testing/assertions/assertions2/factorial_test.go

* "Dot import" usage

.code testing/assertions/assertions3/factorial_test.go

* Go test tips&tricks
- you can use build tags and/or short mode
- good practice auxiliary data in testdata sub-directory/package, ignored by go build

* Example 1
.code lesson5/cgo-math-test-bench/cgo-math_test.go /T1/,/T1/

* Example 2
.code lesson5/cgo-math-test-bench/cgo-math_test.go /T2/,/T2/

* Example 3
.code lesson5/cgo-math-test-bench/cgo-math_test.go /benchmark/,/benchmark/

* CGo

* CGo?
- C and Go, Cgo, but not a Go
- allows  interoperability between Go and C code
- calling C function in Go and Go functions in C
- "FFI"
- "C" "meta" package

* CGo
- has overhead, look for solution in Go
- C code can't hold pointers in to the Go world
- ^^ due to the copying nature of the GC
- need to manually free malloc'ed(heap) C memory
- string, arrays and such

* Example C in Go inline
.code lesson5/cgo-inlinec/cgo-inlinec.go

* Example C in Go separate files
.code lesson5/cgo-independent/cgo-independent.go

* Example memory management with CGo and C strings
.code lesson5/cgo-strings/cgo-string.go /memory management/,/memory management end/

* Example Go in C
- don't
- again don't
- look at the CGo docs
- BEWARE! it has extreme overhead

* Builtin tools
- go vet
- reports suspicions code construct, possible bugs
- go fmt
- formats code to the common coding standard
- go fix
- forward ports your code to latest release version of Go

* External tools
- abcgo
- gosec
- gocyclo
- goconst
- (go)errcheck
- gocritic
- golangci-lint

* Dependency management

* The Past
- go get and GOPATH
- vendoring aka bundling
- plethora of tools, godep, govendor, glide

* The Present
- Go modules, go mod
- local cache instead of GOPATH
- go mod
- go.mod storing informations for module
- init, vendor, download
- go get bar@...
- go list -m
- go list -u -m -json all
- go list -u -m -json all | go-mod-outdated -update

* Proxies and sumdbs
- Proxies facilitates fetches, instead of direct
- SumDBs hashes of repos for corresponding versions

* The future?
-?

#last slide
* More Gophers
#The Go gopher was designed by Renee French. (http://reneefrench.blogspot.com/)
#Source https://golang.org/doc/gopher/bumper.png
#The design and this image is licensed under the Creative Commons 3.0 Attributions license.
.image ./common/bumper.png  _ 900