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Testing Go CLI Applications with Test Script Jakub Jarosz Belfast Gophers Meetup - February 2023

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cli applications http://blog.chriss-baumann.de/2010/07/26/because-life-is-too-short-for-manual-testing

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cli applications & testscript http://blog.chriss-baumann.de/2010/07/26/because-life-is-too-short-for-manual-testing

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testscript - run commands exec echo 'Hello Gophers!' stdout 'Hello Gophers\n'

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testscript - run commands ! exec cat not_existing_file.txt stderr 'cat: not_existing_file.txt: No such file or directory'

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testscript - run binaries exec hello stdout 'Hello Belfast Gophers\n'

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testscript - run binaries with args exec hello Shawn stdout 'Hello Gopher, Shawn' ! stderr .

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testscript - run binaries with args ! exec hello ! stdout . stderr 'usage: Hello Gopher NAME'

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testscript - code coverage

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testscript - cmp & golden files exec hello Kate cmp stdout golden.txt -- golden.txt -- Hello Gopher, Kate!

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testscript - exists, grep & regex exec hello Michael -o greet.txt exists greet.out grep 'Michael' greet.out

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testscript - txtar files & dir structure -- misc/file1.txt -- ... -- misc/subfolder/file2.txt -- ... -- etc/file3.txt -- ...

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testscript - file operations cp rm mv mkdir …

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testscript - comments & test phases # Test 1 - run hello without argos ... # Test 2 - run hello with args ... # Test 3 - run hello with invalid args ...

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testscript - env vars env API_KEY= ! exec myprog stderr 'API_KEY must be set'

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testscript - conditions [go1.16] exec echo 'We have at least Go 1.16' [!arm64] exec echo 'This is a non-arm64 machine' [darwin] exec echo 'We''re on macOS'

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testscript - extensions (custom functions)

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testscript - background test steps

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testscript - example project structure ── hello ├── go.mod ├── go.sum ├── hello.go ├── hello_test.go └── testdata └── script └── hello.txtar

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testscript.Run func TestScript(t *testing.T) { testscript.Run(t, testscript.Params{ Dir: "testdata/script", }) }

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testscript.RunMain func TestMain(m *testing.M) { os.Exit(testscript.RunMain(m, map[string]func() int{ "hello": hello.RunCLI, })) }

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testscript - standalone testscript runner testscript testdata/script/*

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summary ● Excellent for testing CLI tools and binaries ● Runs along other tests ● Saves time ● Builds confidence ● It’s derived directly from the code used to test Go tool itself!

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resources ● pkg.go.dev/github.com/rogpeppe/go-i nternal/testscript ● github.com/mvdan/go-internal ● bitfieldconsulting.com/books/tests ● github.com/MariaLetta/free-gophers- pack ● github.com/qba73/belfast-go-meetup ● github.com/qba73/habit

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Thank You! Jakub Jarosz github, twitter @qba73 | linkedin.com/in/jakubjarosz