Dive deep into Go 1.15 changes to testing package

The presentation materials for Go 1.15 Release Party in Japan

Transcript

1. Dive deep into Go 1.15 changes to testing package Go 1.15 Release Party, AUGUST 31 2020 #go115party @hgsgtk Kazuki Higashiguchi
2. { About me Kazuki Higashiguchi GitHub/Twitter: @hgsgtk BASE BANK, Inc. (BASE, Inc.)
3. Go 1.15 Release Notes > Minor changes to the testing The testing.T type now has a Deadline method ... A TestMain function is no longer required to call os.Exit. ... The new methods T.TempDir and B.TempDir ... go test -v now groups output by test name, ... https://golang.org/doc/go1.15#testing
4. Go 1.15 Release Notes > Minor changes to the testing The testing.T type now has a Deadline method ... A TestMain function is no longer required to call os.Exit. ... The new methods T.TempDir and B.TempDir ... go test -v now groups output by test name, ... https://golang.org/doc/go1.15#testing Talk contents
5. 01 A TestMain function is no longer required to call os.Exit Minor changes to the testing in 1.15
6. Go 1.15 Release Notes > Minor changes to the library > testing A TestMain function is no longer required to call os.Exit. If a TestMain function returns, the test binary will call os.Exit with the value returned by m.Run. https://golang.org/doc/go1.15#testing
7. 1.15 or later, no longer required to call os.Exit No need to call os.Exit()
8. https://github.com/golang/go/issues/34129 testing: TestMain should not require os.Exit #34129 Issued at 2019.9.26
9. Common TestMain() mistakes $ go test -v ./... === RUN TestHoge --- FAIL: TestHoge (0.00s) FAIL ok github.com/hgsgtk/go-snippets/testing -115/mistake 0.079s defer os.Exit()
10. Issue #34129 testing: TestMain should not require os.Exit https://github.com/golang/go/issues/34129 “This mistake does happen a lot, and the testing package that called TestMain and prepared the m can certainly record the result of m.Run for use in its own outer os.Exit.” (@rsc Russ Cox)
11. https://go-review.googlesource.com/c/go/+/219639 219639: testing: do not require os.Exit in TestMain Major change files ... src/testing/testing.go src/cmd/go/internal/load/ test.go
12. `go test ./...` with TestMain (before 1.15) `go test` generate _testmain.go code. src/cmd/go/main.go main() src/cmd/go/internal/test/test.go runTest() -> builderTest() src/cmd/go/internal/load TestPackagesFor() -> TestPackagesAndErrors() -> formatTestMain() -> testmainTmpl Template code generated by `go test` ( _testmain.go) SUT _test.go TestMain 1. Call testing.MainStart() src/testing/testing.go MainStart() 2. Call user-defined TestMain
13. `go test ./...` with TestMain (1.15 or later) Go 1.15 or later, main func in `_testmain.go` call os.Exit(). src/cmd/go/main.go main() src/cmd/go/internal/test/test.go runTest() -> builderTest() src/cmd/go/internal/load TestPackagesFor() -> TestPackagesAndErrors() -> formatTestMain() -> testmainTmpl Template code generated by `go test` ( _testmain.go) SUT _test.go TestMain 1. Call testing.MainStart() src/testing/testing.go MainStart() 2. Call user-defined TestMain 3. Call os.Exit() with m.Run result code
14. src/testing/testing.go https://go-review.googlesource.com/c/go/+/219639/10/src/testing/testing.go m.Run records its own result in an unexported field of m.
15. src/cmd/go/internal/load/test.go https://go-review.googlesource.com/c/go/+/219639/10/src/cmd/go/internal/load/test.go if TestMain(m) returns, the outer test func main harness calls os.Exit with that code.
16. A TestMain function is no longer required to call os.Exit • A TestMain function is no longer required to call os.Exit • testing.M の内部変更及び、 go test で生成される main 関 数のテンプレート修正によって実現されている
17. 02 Minor changes to the testing in 1.15 The testing.T type now has a Deadline method
18. Go 1.15 Release Notes > Minor changes to the library > testing The testing.T type now has a Deadline method that reports the time at which the test binary will have exceeded its timeout. https://golang.org/doc/go1.15#testing
19. t.Deadline() https://godoc.org/testing#T.Deadline Deadline reports the time at which the test binary will have exceeded the timeout specified by the -timeout flag. The ok result is false if the -timeout flag indicates “no timeout” (0). % go test -v -timeout=5s -run=TestDeadlineConfirm t.Deadline() = 2020-08-31 18:37:39.502862 +0900 JST m=+5.000488349, timeout set = true $ go test -v -timeout=0 -run=TestDeadlineConfirm t.Deadline() = 0001-01-01 00:00:00 +0000 UTC, timeout set = false
20. https://github.com/golang/go/issues/28135 testing: add (*T).Deadline #28135 Issued at Oct 11, 2018
21. https://go-review.googlesource.com/c/go/+/202758/ 202758: testing: testing: add (*T).Deadline method for test timeout Major change files ... src/testing/testing.go
22. Inside src/testing/testing.go ※ 今回の変更に関連するものだけ抜粋しています testing.M.Run() runTests() testing.M.startAlarm() testing.T.Run() testing.T.Deadline() …..
23. src/testing/testing.go https://golang.org/src/testing/testing.go#L630 New field ‘deadline’ in testContext New method T.Deadline() testing.T has *testContext
24. src/testing/testing.go https://go-review.googlesource.com/c/go/+/202758/8/src/testing/testing.go t.Deadline() added in testing.go m.Run() call it. Pass arg to runTests()
25. src/testing/testing.go https://go-review.googlesource.com/c/go/+/202758/8/src/testing/testing.go runTests() set deadline to testContext.deadline
26. The testing.T type now has a Deadline method • A new method t.Deadline • It is realized by adding `deadline` field in testContext in testing.T
27. Congrats Go 1.15 !!