! go test
stdout 'main_test.go:6: expected panic'
stdout 'main_test.go:7: expected S, got string'

-- main_test.go --
package main

import "testing"

func Test(t *testing.T) {
        blah(t, func() {})
        blah2(t, func() { panic("oh dear") })
}

func blah(t *testing.T, f func()) {
        t.Helper()

        defer func() {
                t.Helper()

                err := recover()
                if err == nil {
                        t.Errorf("expected panic")
                }
        }()
        f()
}

func blah2(t *testing.T, f func()) {
        t.Helper()

        defer func() {
                t.Helper()
                err := recover()
                if _, ok := err.(S); !ok {
                        t.Errorf("expected S, got %T", err)
                }
        }()
        f()
}

type S struct{}

> ! go test
[stdout]
--- FAIL: Test (0.00s)
    main_test.go:6: expected panic
    panic.go:522: expected S, got string
FAIL
exit status 1
FAIL    _$WORK  0.002s

[exit status 1]
> stdout 'main_test.go:6: expected panic'
> stdout 'main_test.go:7: expected S, got string'
FAIL: /tmp/testscript728881261/0/script.txt:5: no match for `main_test.go:7: expected S, got string` found in stdout
error running t_helper_panic.txt in /tmp/testscript728881261/0