Sometimes a test need to call os.Chdir(). Here is a bare minimum implementation of what's needed from a test to do that:

        oldwd, err := Getwd()    
        if err != nil {
                t.Fatal(err)
        }
        if err := Chdir(dir); err != nil {
                t.Fatal(err)
        }
        t.Cleanup(func() {
                if err := Chdir(oldwd); err != nil {
                        // It's not safe to continue with tests if we can't get back to
                        // the original working directory.
                        panic(err)
                }
        })

The code above can be used as a test helper; in fact, this repository already contains at least 5 helpers similar to the one above:

1. go/src/os/os_windows_test.go

   Line 35 in 1d538f1

   func chdir(t *testing.T, dir string) {

2. go/src/os/os_test.go

   Line 917 in 1d538f1

   func chtmpdir(t *testing.T) func() {

3. go/src/path/filepath/path_test.go

   Line 510 in 1d538f1

   func chdir(t *testing.T, dir string) {

4. go/src/path/filepath/path_test.go

   Line 527 in 1d538f1

   func chtmpdir(t *testing.T) (restore func()) {

5. go/src/syscall/syscall_linux_test.go

   Line 27 in 1d538f1

   func chtmpdir(t *testing.T) func() {

In addition, there are a few in-line implementations of the same functionality, another implementation in golang.org/x/sys/unix and so on.

The problem with this (except for multiple implementations and re-implementations) is, tests that use it can not use t.Parallel. Currently, there is no way to ensure that.

The issue is very similar to one for os.Setenv (#41260, fixed by https://golang.org/cl/326790); thus the solution is also similar.

The proposal is to add a Chdir method to the testing package, which will take care about all of the above.

The implementation may look like this: https://go-review.googlesource.com/c/go/+/529895