Split out tests for errexit and run them on busybox ash.

Alpine Linux abuild uses errexit with ash.

spec/errexit.test.sh

@@ -0,0 +1,206 @@
#!/usr/bin/env bash
#
# Usage:
#   ./errexit.test.sh <function name>

### errexit aborts early
set -o errexit
false
echo done
# stdout-json: ""
# status: 1

### errexit for nonexistent command
set -o errexit
nonexistent__ZZ
echo done
# stdout-json: ""
# status: 127

### errexit aborts early on pipeline
set -o errexit
echo hi | grep nonexistent
echo two
# stdout-json: ""
# status: 1

### errexit with { }
# This aborts because it's not part of an if statement.
set -o errexit
{ echo one; false; echo two; }
# stdout: one
# status: 1

### errexit with if and { }
set -o errexit
if { echo one; false; echo two; }; then
  echo three
fi
echo four
# stdout-json: "one\ntwo\nthree\nfour\n"
# status: 0

### errexit with ||
set -o errexit
echo hi | grep nonexistent || echo ok
# stdout: ok
# status: 0

### errexit with &&
set -o errexit
echo ok && echo hi | grep nonexistent 
# stdout: ok
# status: 1

### errexit test && -- from gen-module-init
set -o errexit
test "$mod" = readline && echo "#endif"
echo status=$?
# stdout: status=1

### errexit test && and fail
set -o errexit
test -n X && false
echo status=$?
# stdout-json: ""
# status: 1

### errexit and loop
set -o errexit
for x in 1 2 3; do
  test $x = 2 && echo "hi $x"
done
# stdout: hi 2
# status: 1

### errexit and brace group { }
set -o errexit
{ test no = yes && echo hi; }
echo status=$?
# stdout: status=1

### errexit and time { }
set -o errexit
time false
echo status=$?
# status: 1

### errexit with !
set -o errexit
echo one
! true
echo two
! false
echo three
# stdout-json: "one\ntwo\nthree\n"
# status: 0

### errexit with ! and ;
# AST has extra Sentence nodes; there was a REGRESSION here.
set -o errexit; echo one; ! true; echo two; ! false; echo three
# stdout-json: "one\ntwo\nthree\n"
# status: 0

### errexit with while/until
set -o errexit
while false; do
  echo ok
done
until false; do
  echo ok  # do this once then exit loop
  break
done
# stdout: ok
# status: 0

### errexit with (( ))
# from http://mywiki.wooledge.org/BashFAQ/105, this changed between verisons.
# ash says that 'i++' is not found, but it doesn't exit.  I guess this is the 
# subshell problem?
set -o errexit
i=0
(( i++ ))
echo done
# stdout-json: ""
# status: 1
# N-I dash status: 127
# N-I dash stdout-json: ""
# BUG ash status: 0
# BUG ash stdout: done

### errexit with subshell
set -o errexit
( echo one; false; echo two; )
# stdout: one
# status: 1

### errexit with command sub
# This is the bash-specific bug here:
# https://blogs.janestreet.com/when-bash-scripts-bite/
set -o errexit
s=$(echo one; false; echo two;)
echo "$s"
# stdout-json: ""
# status: 1
# BUG ash/bash status: 0
# BUG ash/bash stdout-json: "one\ntwo\n"

### errexit with local
# I've run into this problem a lot.
# https://blogs.janestreet.com/when-bash-scripts-bite/
set -o errexit
f() {
  echo good
  local x=$(echo bad; false)
  echo $x
}
f
# stdout-json: "good\n"
# status: 1
# BUG bash/dash/mksh/ash stdout-json: "good\nbad\n"
# BUG bash/dash/mksh/ash status: 0

### setting errexit while it's being ignored
# ignored and then set again
set -o errexit
# osh aborts early here
if { echo 1; false; echo 2; set -o errexit; echo 3; false; echo 4; }; then
  echo 5;
fi
echo 6
false  # this is the one that makes other shells fail
echo 7
# status: 1
# stdout-json: "1\n2\n"
# OK dash/bash/mksh/ash stdout-json: "1\n2\n3\n4\n5\n6\n"

### setting errexit in a subshell works but doesn't affect parent shell
( echo 1; false; echo 2; set -o errexit; echo 3; false; echo 4; )
echo 5
false
echo 6
# stdout-json: "1\n2\n3\n5\n6\n"
# status: 0

### setting errexit while it's being ignored in a subshell
set -o errexit
if ( echo 1; false; echo 2; set -o errexit; echo 3; false; echo 4 ); then
  echo 5;
fi
echo 6  # This is executed because the subshell just returns false
false 
echo 7
# status: 1
# stdout-json: "1\n2\n6\n"
# OK dash/bash/mksh/ash stdout-json: "1\n2\n3\n4\n5\n6\n"

### errexit double quard
# OSH bug fix.  ErrExit needs a counter, not a boolean.
set -o errexit
if { ! false; false; true; } then
  echo true
fi
false
echo done
# status: 1
# stdout-json: "true\n"