x/tools/gopls: renaming functions should rename corresponding test functions

[jtagcat]

testrename.mp4

Renaming a function also renames references to it. If there is a correspondingly named test function, it'd make sense to also rename it (TestHello to TestFoo when Hello renamed to Foo). Keeping the names in sync, and reducing work burden.

[findleyr]

Sure, that would be cool, and seems like a useful feature (we already rename symbols in comments)! Marking this as help wanted.

[findleyr]

@h9jiang points out that the 'AddTests' code action already looks for an existing test following the standard naming schema, so there is precedent for us honoring this convention.

[AlexsanderHamir]

Hi, I’d love to help contribute this feature if that's okay, I’ve been reviewing the existing refactor/rename package and have started outlining a possible technical approach.

[h9jiang]

Hi AlexsanderHamir@

Thanks! I think the most important bit is how to correctly find the test function based on the function you are observing. And the other way around, how to find the function based on the test function you are observing. E.g. (From function Foo to function TestFoo, from function TestFoo to function Foo).

The name determination can be found this testName function. You should be able to do a reverse engineering to find the original function by looking at the test function name.

But one more thing to notice is, following the naming convention might not be enough. I think to make sure we have a higher chance of locating the right function, we want to make sure the function or method is actually being called within the test function.

-- foo_test.go --

import (
  renamed "..../foo"
)
func TestFoo() {
    // ....
    renamed .Foo()
    // ....
}

-- foo.go --
package foo

func Foo() {
    // ....
}

To verify the function Foo is actually being called inside of the test function, we need to make sure both the package and the function are correct. In the example above, (probably the most complicated case), the package foo get renamed in the test file as renamed. But this is still considered as a valid case. The qualifier function maybe helpful for understanding.

I think the rename is pretty straightforward. I hope.

[findleyr]

@AlexsanderHamir I've assigned this to you. Please let us know if you have any difficulty implementing it or want advice.

If you find you can't implement it, just let us know or unassign yourself.

Thanks!