[Fix] tests: Bash 4.2 empty-array expansion under set -u; issue #485

[Fix] 30-monitor-utils.bats: monitor_scan_owner_filters unit tests used
      "${_owner_filter_args[@]}" and "${ignore_root[@]}" etc. inside
      _source_lmd_stack's set -eu scope; Bash 4.2 (CentOS 7) treats
      "${arr[@]}" of an empty array as unbound under set -u, causing
      4 test failures. Replace with Bash 4.2-safe idiom:
      ${arr+"${arr[@]}"} (expands to nothing when arr is empty,
      expands normally when arr has elements). Tests 88-91 now
      pass on all 9 OS targets; issue #485.

Author: rfxn

tests/30-monitor-utils.bats

@@ -300,11 +300,16 @@ EVENTS
     # default toggle: owner filters NOT applied
     monitor_scan_owner_filters="0"
     if [ "${monitor_scan_owner_filters:-0}" = "1" ]; then
-        _owner_filter_args=("${ignore_root[@]}" "${ignore_user[@]}" "${ignore_group[@]}")
+        _owner_filter_args=(
+            ${ignore_root+"${ignore_root[@]}"}
+            ${ignore_user+"${ignore_user[@]}"}
+            ${ignore_group+"${ignore_group[@]}"}
+        )
     fi
+    # ${arr+"${arr[@]}"} — Bash 4.2-safe empty-array expansion under set -u (centos7)
     run find "$tmpfile" -maxdepth 0 -type f \
         -size +"${scan_min_filesize}c" \
-        "${_owner_filter_args[@]}"
+        ${_owner_filter_args+"${_owner_filter_args[@]}"}
     [ "$status" -eq 0 ]
     [ "$output" = "$tmpfile" ]
     rm -rf "$tmpdir"
@@ -325,11 +330,16 @@ EVENTS
     # default toggle off — ignore_root/ignore_user suppressed in monitor
     monitor_scan_owner_filters="0"
     if [ "${monitor_scan_owner_filters:-0}" = "1" ]; then
-        _owner_filter_args=("${ignore_root[@]}" "${ignore_user[@]}" "${ignore_group[@]}")
+        _owner_filter_args=(
+            ${ignore_root+"${ignore_root[@]}"}
+            ${ignore_user+"${ignore_user[@]}"}
+            ${ignore_group+"${ignore_group[@]}"}
+        )
     fi
+    # ${arr+"${arr[@]}"} — Bash 4.2-safe empty-array expansion under set -u (centos7)
     run find "$tmpfile" -maxdepth 0 -type f \
         -size +"${scan_min_filesize}c" \
-        "${_owner_filter_args[@]}"
+        ${_owner_filter_args+"${_owner_filter_args[@]}"}
     [ "$status" -eq 0 ]
     [ "$output" = "$tmpfile" ]
     rm -rf "$tmpdir"
@@ -349,11 +359,16 @@ EVENTS
     # opt-in toggle: owner filters ARE applied (rc3 behavior)
     monitor_scan_owner_filters="1"
     if [ "${monitor_scan_owner_filters:-0}" = "1" ]; then
-        _owner_filter_args=("${ignore_root[@]}" "${ignore_user[@]}" "${ignore_group[@]}")
+        _owner_filter_args=(
+            ${ignore_root+"${ignore_root[@]}"}
+            ${ignore_user+"${ignore_user[@]}"}
+            ${ignore_group+"${ignore_group[@]}"}
+        )
     fi
+    # ${arr+"${arr[@]}"} — Bash 4.2-safe empty-array expansion under set -u (centos7)
     run find "$tmpfile" -maxdepth 0 -type f \
         -size +"${scan_min_filesize}c" \
-        "${_owner_filter_args[@]}"
+        ${_owner_filter_args+"${_owner_filter_args[@]}"}
     # root-owned file excluded by ignore_root=(-not -uid 0 -not -gid 0)
     [ "$status" -eq 0 ]
     [ -z "$output" ]
@@ -378,15 +393,16 @@ EVENTS
     ignore_file_ext="$ext_file_orig"  # restore before any return path
     local _owner_filter_args=()
     monitor_scan_owner_filters="0"
+    # ${arr+"${arr[@]}"} — Bash 4.2-safe empty-array expansion under set -u (centos7)
     # .php is admitted; .log is excluded by ignore_fext_args
     run find "$tmpfile_php" -maxdepth 0 -type f \
         -size +"${scan_min_filesize}c" \
-        "${ignore_fext_args[@]}" "${_owner_filter_args[@]}"
+        "${ignore_fext_args[@]}" ${_owner_filter_args+"${_owner_filter_args[@]}"}
     [ "$status" -eq 0 ]
     [ "$output" = "$tmpfile_php" ]
     run find "$tmpfile_log" -maxdepth 0 -type f \
         -size +"${scan_min_filesize}c" \
-        "${ignore_fext_args[@]}" "${_owner_filter_args[@]}"
+        "${ignore_fext_args[@]}" ${_owner_filter_args+"${_owner_filter_args[@]}"}
     [ "$status" -eq 0 ]
     [ -z "$output" ]
     rm -rf "$tmpdir"