diff --git a/src/cmd/ksh93/tests/arrays.sh b/src/cmd/ksh93/tests/arrays.sh
index 2130aac1c..d8d55c294 100755
--- a/src/cmd/ksh93/tests/arrays.sh
+++ b/src/cmd/ksh93/tests/arrays.sh
@@ -729,5 +729,12 @@ do
 		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 done
 
+# ======
+# https://github.com/att/ast/issues/23
+unset foo bar
+typeset -a foo=([1]=w [2]=x) bar=(a b c)
+foo+=("${bar[@]}")
+[[ $(typeset -p foo) == 'typeset -a foo=([1]=w [2]=x [3]=a [4]=b [5]=c)' ]] || err_exit 'Appending does not work if array contains empty indexes'
+
 # ======
 exit $((Errors<125?Errors:125))
diff --git a/src/cmd/ksh93/tests/basic.sh b/src/cmd/ksh93/tests/basic.sh
index f0cdfb072..7aa1fea59 100755
--- a/src/cmd/ksh93/tests/basic.sh
+++ b/src/cmd/ksh93/tests/basic.sh
@@ -795,7 +795,7 @@ trap - DEBUG  # bug compat
 # In ksh93v- and ksh2020 EXIT traps don't work in forked subshells
 # https://github.com/att/ast/issues/1452
 exp="forked subshell EXIT trap okay"
-got="$(ulimit -t unlimited; trap 'echo forked subshell EXIT trap okay' EXIT)"
+got="$(ulimit -t unlimited 2> /dev/null; trap 'echo forked subshell EXIT trap okay' EXIT)"
 [[ $got == $exp ]] || err_exit "EXIT trap did not trigger in forked subshell" \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
diff --git a/src/cmd/ksh93/tests/builtins.sh b/src/cmd/ksh93/tests/builtins.sh
index d66f90f68..392405c2c 100755
--- a/src/cmd/ksh93/tests/builtins.sh
+++ b/src/cmd/ksh93/tests/builtins.sh
@@ -40,14 +40,14 @@ got=$(getconf -l | awk '{ gsub(/=.*/, "") } /[[:upper:]]/ { print }')
 exp="GETCONF=\"$bingetconf\""
 got=$(getconf -q | grep 'GETCONF=')
 [[ $exp == "$got" ]] || err_exit "'getconf -q' fails to quote string values" \
-	"(expected $exp, got $got)"
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
 # The -n option should only return matching names.
 # https://github.com/ksh93/ksh/issues/279
 exp="GETCONF=$bingetconf"
 got=$(getconf -n GETCONF)
 [[ $exp == "$got" ]] || err_exit "'getconf -n' doesn't match names correctly" \
-	"(expected $exp, got $got)"
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
 # ======
 # Test shell builtin commands
@@ -1201,12 +1201,12 @@ exp=$(uname -o)
 
 # Test for a possible crash (to avoid crashing the script, fork the subshell)
 (
-	ulimit -t unlimited
+	ulimit -t unlimited 2> /dev/null
 	uname -d > /dev/null
 ) || err_exit "'uname -d' crashes"
 
 # 'uname -d' shouldn't change the output of 'uname -o'
-got=$(ulimit -t unlimited; uname -d > /dev/null; uname -o)
+got=$(ulimit -t unlimited 2> /dev/null; uname -d > /dev/null; uname -o)
 [[ $exp == $got ]] || err_exit "'uname -d' changes the output of 'uname -o'" \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
diff --git a/src/cmd/ksh93/tests/functions.sh b/src/cmd/ksh93/tests/functions.sh
index 3df8813c1..731c1a6e0 100755
--- a/src/cmd/ksh93/tests/functions.sh
+++ b/src/cmd/ksh93/tests/functions.sh
@@ -31,9 +31,25 @@ bin_echo=$(whence -p echo)
 bin_sleep=$(whence -p sleep)
 bin_kill=$(whence -p kill)
 
+# ======
+# In ksh93v- and ksh2020 eval'ing a function definition may dump the function body to stdout.
+# https://github.com/att/ast/issues/1160
+got="$($SHELL -c '
+	for ((i=0; i<1025; i++))
+	do	str="${str}12345678"
+	done
+	eval "foo() { $str; }"
+
+	baz() { eval "bar() { FAILURE; }"; }
+	( baz >&3 ) 3>&1
+')"
+[[ -n "$got" ]] && err_exit "eval'ing function dumps function body to stdout" \
+	"(got $(printf %q "$got"))"
+
+# ======
+# Check for global variables and $0
 integer foo=33
 bar=bye
-# check for global variables and $0
 function foobar
 {
 	case $1 in
diff --git a/src/cmd/ksh93/tests/io.sh b/src/cmd/ksh93/tests/io.sh
index 0ad2f71fa..77d1171ab 100755
--- a/src/cmd/ksh93/tests/io.sh
+++ b/src/cmd/ksh93/tests/io.sh
@@ -283,12 +283,22 @@ EOF) == 'hello world' ]] || err_exit 'invalid readahead on stdin'
 $SHELL -c 'exec 3>; /dev/null'  2> /dev/null && err_exit '>; with exec should be an error'
 $SHELL -c ': 3>; /dev/null'  2> /dev/null || err_exit '>; not working with at all'
 print hello > $tmp/1
-if	! $SHELL -c "false >; $tmp/1"  2> /dev/null
-then	let 1;[[ $(<$tmp/1) == hello ]] || err_exit '>; not preserving file on failure'
-fi
-if	! $SHELL -c "sed -e 's/hello/hello world/' $tmp/1" >; $tmp/1  2> /dev/null
-then	[[ $(<$tmp/1) == 'hello world' ]] || err_exit '>; not updating file on success'
-fi
+$SHELL -c "false >; $tmp/1"
+status=$?
+(( status == 1 )) || err_exit "unexpected exit status" \
+	"(expected 1, got $status)"
+exp='hello'
+got=$(<$tmp/1)
+[[ $got == "$exp" ]] || err_exit '>; not preserving file on failure' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+$SHELL -c "sed -e 's/hello/hello world/' $tmp/1" >; $tmp/1
+status=$?
+(( status == 0 )) || err_exit "unexpected exit status" \
+	"(expected 0, got $status)"
+exp='hello world'
+got="$(<$tmp/1)"
+[[ $got == "$exp" ]] || err_exit '>; not updating file on success' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
 $SHELL -c 'exec 3<>; /dev/null'  2> /dev/null && err_exit '<>; with exec should be an error'
 $SHELL -c ': 3<>; /dev/null'  2> /dev/null || err_exit '<>; not working with at all'
@@ -474,13 +484,6 @@ do      out=$("$binfalse" 2>/dev/null)
 	fi
 done
 
-rm -f $tmp/file1 $tmp/file2
-print foo > $tmp/file3
-ln -s $tmp/file3 $tmp/file2
-ln -s $tmp/file2 $tmp/file1
-print bar >; $tmp/file1
-[[ $(<$tmp/file3) == bar ]] || err_exit '>; not following symlinks'
-
 for i in 1
 do	:
 done	{n}< /dev/null
@@ -639,8 +642,8 @@ fi
 
 # ======
 # "&>file" redirection operator, shorthand for ">file 2>&1" (new as of 93u+m; inherited from old SHOPT_BASH)
-if	[[ -o ?posix ]]
-then	set -o posix
+if	[[ -o ?posix ]] && command set -o posix
+then
 	# This should print in a background job, then create an empty file, as '>aha1.txt' is a separate command.
 	eval '	print -u1 bad1 &>aha1.txt
 		print -u2 bad2 &>aha2.txt
@@ -654,11 +657,8 @@ then	set -o posix
 	' >/dev/null 2>&1
 	[[ $(< aha1.txt) == ok1 ]] || err_exit '&> does not redirect stdout'
 	[[ $(< aha2.txt) == ok2 ]] || err_exit '&> does not redirect stderr'
-fi
-
-# In POSIX mode, file descriptors > 2 should remain open when invoking another program
-if	[[ -o ?posix ]]
-then	(set -o posix; exec 7>ok.txt; "$SHELL" -c 'print ok >&7' 2>/dev/null)
+	# In POSIX mode, file descriptors > 2 should remain open when invoking another program
+	(set -o posix; exec 7>ok.txt; "$SHELL" -c 'print ok >&7' 2>/dev/null)
 	[[ $(<ok.txt) == ok ]] || err_exit 'File descriptors > 2 not inherited in POSIX mode'
 fi
 (exec 7>bad.txt; "$SHELL" -c 'print bad >&7' 2>/dev/null)
@@ -853,5 +853,30 @@ cat >out2 < <(case x in x) cat out1;; esac)
 [[ $(<out2) == ok ]] || err_exit "process substitution not working as file name to redirection" \
 	"(expected 'ok', got $(printf %q "$(<out2)"))"
 
+# ======
+# Reading a file through a command substitution
+# https://github.com/att/ast/issues/203
+TMPF=$tmp/tmpf
+echo foo >$TMPF
+export TMPF
+[[ -n "$($SHELL -c 'echo $(<$TMPF)' <&-)" ]] || err_exit "Closing stdin causes failure when reading file through \$(<)"
+[[ -n "$($SHELL -c "$SHELL -c 'echo \$(<$TMPF) >&2' >&-" 2>&1)" ]] || err_exit "Closing stdout causes failure when reading file through \$(<)"
+[[ -n "$($SHELL -c 'echo $(<$TMPF)' 2>&-)" ]]  || err_exit "Closing stderr causes failure when reading file through \$(<)"
+
+# ======
+# Verify that symlinks are correctly canonicalized as part of a conditional redirection.
+# https://github.com/att/ast/issues/492
+mkdir -p dir1/dir2
+ln -s dir1 s1
+cd dir1
+ln -s dir2 s2
+cd ..
+exp=symlinks-resolved
+print wrong-answer > dir1/dir2/x
+print $exp >; s1/s2/x
+got=$(< dir1/dir2/x)
+[[ $got == "$exp" ]] || err_exit "symlink in conditional redirect wrong" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))
diff --git a/src/cmd/ksh93/tests/pty.sh b/src/cmd/ksh93/tests/pty.sh
index 02771ab7f..7d5f0c317 100755
--- a/src/cmd/ksh93/tests/pty.sh
+++ b/src/cmd/ksh93/tests/pty.sh
@@ -577,6 +577,10 @@ actual=$(echo begin; exec >/dev/tty; [ -t ] && test -t) \
 && echo OK7 || echo 'test -t in comsub with exec >/dev/tty fails'
 actual=$(echo begin; exec >/dev/tty; [ -n X -a -t ] && test -n X -a -t) \
 && echo OK8 || echo 'test -t in comsub with exec >/dev/tty fails (compound expression)'
+# The broken ksh2020 fix for [ -t 1 ] (https://github.com/att/ast/pull/1083) caused
+# [ -t 1 ] to fail in non-comsub virtual subshells.
+( test -t 1 ) && echo OK9 || echo 'test -t 1 in virtual subshell fails'
+( test -t ) && echo OK10 || echo 'test -t in virtual subshell fails'
 EOF
 tst $LINENO <<"!"
 L test -t 1 inside command substitution
@@ -593,6 +597,8 @@ r ^OK5\r\n$
 r ^OK6\r\n$
 r ^OK7\r\n$
 r ^OK8\r\n$
+r ^OK9\r\n$
+r ^OK10\r\n$
 r ^:test-2:
 !
 
@@ -841,5 +847,16 @@ r \t#foo\r\n$
 r \thist -lnN 1\r\n$
 !
 
+# err_exit #
+((SHOPT_VSH || SHOPT_ESH)) && tst $LINENO <<"!"
+L tab completion while expanding ${.sh.*} variables
+# https://github.com/att/ast/issues/1461
+
+d 15
+p :test-1:
+w test \$\{.sh.level\t
+r ^:test-1: test \$\{.sh.level\}\r\n$
+!
+
 # ======
 exit $((Errors<125?Errors:125))
diff --git a/src/cmd/ksh93/tests/shtests b/src/cmd/ksh93/tests/shtests
index e3f6748d9..53c3ef266 100755
--- a/src/cmd/ksh93/tests/shtests
+++ b/src/cmd/ksh93/tests/shtests
@@ -446,7 +446,7 @@ print "Total errors: $total_e"
 # if we have the 'times' builtin and can use process substitution with output redirection.
 # See:	https://github.com/ksh93/ksh/commit/65d363fd
 #	https://github.com/ksh93/ksh/issues/2
-if 	(	ulimit -t unlimited	# fork to circumvent old ksh bugs
+if 	(	ulimit -t unlimited 2> /dev/null  # fork to circumvent old ksh bugs
 		unalias times
 		PATH=/dev/null whence -q times || exit
 		cd "$tmp" || exit
diff --git a/src/cmd/ksh93/tests/variables.sh b/src/cmd/ksh93/tests/variables.sh
index 4c94e1eeb..937c85066 100755
--- a/src/cmd/ksh93/tests/variables.sh
+++ b/src/cmd/ksh93/tests/variables.sh
@@ -1344,5 +1344,14 @@ exp=5
 got=$($SHELL "$lineno_subshell")
 [[ $exp == $got ]] || err_exit "LINENO corrupted after leaving virtual subshell (expected $exp, got $got)"
 
+# ======
+# Check if ${.sh.file} is set to correct value after sourcing a file
+# https://github.com/att/ast/issues/472
+cat > $tmp/foo.sh <<EOF
+echo "foo"
+EOF
+. $tmp/foo.sh > /dev/null
+[[ ${.sh.file} == $0 ]] || err_exit "\${.sh.file} is not set to the correct value after sourcing a file"
+
 # ======
 exit $((Errors<125?Errors:125))