I tried to use go/types to type check a package with internal test files (with package foo) and external test files (with package foo_test). The internal test files expose some symbols that the external test files consume. This works fine in go test. However, the go/types code does not recognize the symbols exported by the internal test files.

I want to use the go/types package to write a refactoring tool that consumes external test files that rely on symbols exported by internal tests files, but I can't because of this error.

I think the issue is that the go/types import logic ignores the internal _test.go files when type-checking the external _test.go files. The go/types config https://golang.org/pkg/go/types/#Config does not seem to have a knob to import _test.go files.

What version of Go are you using (go version)?

go version go1.9 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOOS="darwin"

What did you do?

I created a new package testgotypes with 3 files:

testgotypes.go, without this file gotype doesn't run:

package testgotypes

internal_test.go, which exports a variable for the external test:

package testgotypes

var Export = "hello"

external_test.go, which tries to access the variable exported by internal_test.go:

package testgotypes_test

import (
	"testing"

	"testgotypes"
)

func TestExport(t *testing.T) {
	if testgotypes.Export != "hello" {
		t.Error("uh oh")
	}
}

I ran tests, which worked just fine:

➜  testgotypes git:(master) go test -v  
=== RUN   TestExport
--- PASS: TestExport (0.00s)
PASS
ok  	testgotypes	0.006s

Then I tried to run gotype, compiled from /usr/local/Cellar/go/1.9/libexec/src/go/types/gotype.go:

➜  testgotypes git:(master) gotype -x -t .
external_test.go:10:5: Export not declared by package testgotypes

It fails with the same error my refactoring code sees.

To sanity check gotype, I then renamed internal_test.go to internal.go to make it part of the non-test build. Then gotype is happy:

➜  testgotypes git:(master) mv internal_test.go internal.go
➜  testgotypes git:(master) gotype -x -t .

What did you expect to see?

gotype successfully type checking external_test.go.

What did you see instead?

gotype fails to type check the external_test.go file.