Nailing down the behavior of compound expressions in [

spec/test-builtin.test.sh

@@ -1,4 +1,8 @@
#!/usr/bin/env bash
#
# NOTES:
# - osh is using the external binary.
# - because ! -a -o ( ) are the same, we can share logic with [[.

### empty string is false.  Equivalent to -n.
test 'a'  && echo true
@@ -9,3 +13,16 @@ test ''   || echo false
test -n 'a'  && echo true
test -n ''   || echo false
# stdout-json: "true\nfalse\n"

### ! -a -o
[ -z '' -a ! -z x ] && echo true
# stdout: true

### ( )
[ -z '' -a '(' ! -z x ')' ] && echo true
# stdout: true

### ( ) ! -a -o with system version of [
command [ --version
command [ -z '' -a '(' ! -z x ')' ] && echo true
# stdout: true

test/spec.sh

@@ -239,7 +239,8 @@ if_() {

# NOTE: osh uses external test!  But that's OK for now.
test-builtin() {
  sh-spec spec/test-builtin.test.sh ${REF_SHELLS[@]} $OSH "$@"
  sh-spec spec/test-builtin.test.sh --osh-failures-allowed 1 \
    ${REF_SHELLS[@]} $OSH "$@"
}

builtins() {