Avoid __badType label being executed when the failpoint execution flow is not diverted and the type conversion is successful

[henrybear327]

Revive #19 (as the PR is closed due to the source repo being deleted by the author, I can only reproduce the commits again)

If the code execution flow after the failpoint type conversion doesn't jump to other parts of the code, the __badType will be executed, causing irrelevant error messages to be printed.

For example, consider the following snippet

// gofail: var SomeFuncString string
// log.Println("SomeFuncString", SomeFuncString)

It will be generated into the following snippet

if vSomeFuncString, __fpErr := __fp_SomeFuncString.Acquire(); __fpErr == nil {
	SomeFuncString, __fpTypeOK := vSomeFuncString.(string)
	if !__fpTypeOK {
		goto __badTypeSomeFuncString
	}
	log.Println("SomeFuncString", SomeFuncString)
__badTypeSomeFuncString:
	__fp_SomeFuncString.BadType(vSomeFuncString, "string")
}

As you can see, because log.println doesn't jump to other parts of the code, after printing the log, the code will continue to execute __badTypeSomeFuncString, thus, printing the following message: "SomeFuncString" got value Hello_world of type "string" but expected type "string"

The solution is to add a __nomock label, in the case of type conversion succeeded, thus the __badType label won't be executed.

Reference:

• demo code https://github.com/henrybear327/gofail-perf-fix-demo/tree/issue/val_error

[ArkaSaha30]

Thank you @henrybear327 for the PR, I will be reviewing it shortly.

[ArkaSaha30]

/assign

[henrybear327]

Thank you @henrybear327 for the PR, I will be reviewing it shortly.

Gentle ping :)

I have also rebased it against the latest commit!

[ArkaSaha30]

Hey @henrybear327 👋
I am wondering if we need to update the README.md as well with the __nomock refs

[henrybear327]

Hey @henrybear327 👋 I am wondering if we need to update the README.md as well with the __nomock refs

Thanks @ArkaSaha30 for spotting this! Updated as requested!

[ArkaSaha30]

Thank you @henrybear327 .
The changes look good, cc @ahrtr
/lgtm

[ahrtr]

Thanks for resurrect the PR #19, please also update the examples in https://github.com/etcd-io/gofail/blob/master/doc/design.md#generated-code

[ahrtr]

It would be great if you can add a test in https://github.com/etcd-io/gofail/blob/master/code/rewrite_test.go to verify the generated code is expected.

[henrybear327]

Thanks for resurrect the PR #19, please also update the examples in https://github.com/etcd-io/gofail/blob/master/doc/design.md#generated-code

The generated code is updated! :) Thanks @ahrtr for spotting this missed update!

[henrybear327]

It would be great if you can add a test in https://github.com/etcd-io/gofail/blob/master/code/rewrite_test.go to verify the generated code is expected.

@ahrtr I manually added the generated output to rewrite_test.go, and checked it :)

[ahrtr]

Great work!

Thanks @henrybear327