Add test for ${FUNCNAME[@]}

spec/introspect.test.sh

@@ -0,0 +1,19 @@
#!/usr/bin/env bash
#
# TODO:
# BASH_SOURCE, BASH_LINENO, caller builtin

### ${FUNCNAME[@]} array
f() {
  echo "begin: ${FUNCNAME[@]}"
  g
  echo "end: ${FUNCNAME[@]}"
}
g() {
  echo "func: ${FUNCNAME[@]}"
}
f
# stdout-json: "begin: f\nfunc: g f\nend: f\n"
# N-I mksh stdout-json: "begin: \nfunc: \nend: \n"
# N-I dash stdout-json: ""
# N-I dash status: 2

test/spec.sh

@@ -331,6 +331,12 @@ special-vars() {
    ${REF_SHELLS[@]} $OSH "$@"
}

# dash/mksh don't implement this.
introspect() {
  sh-spec spec/introspect.test.sh --osh-failures-allowed 1 \
    $BASH $OSH "$@"
}

# DONE -- pysh is the most conformant!
tilde() {
  sh-spec spec/tilde.test.sh ${REF_SHELLS[@]} $OSH "$@"