fix(compat): ensure Bash 3.0+ compatibility in parallel optimizations

    Changes for Bash 3.0+ compliance:
    - Replace [[ ]] with [ ] test operators in runner.sh
    - Replace == with = for string comparisons
    - Add fallback from tar to cp+rm for portability
    - Fix indentation to pass EditorConfig linting

    The tar pipe optimization now gracefully falls back to the traditional
    cp + rm approach on systems without tar or with limited tar support,
    ensuring maximum portability while maintaining performance gains on
    systems with modern tar implementations.

Author: Chemaclass

release.sh

@@ -375,15 +375,21 @@ function release::sandbox::create() {
   release::log_info "Creating sandbox at: $SANDBOX_DIR"
 
   # Copy repo content excluding .git, .release-state, node_modules
-  # Use tar pipe for faster copying and built-in exclusions
-  tar --exclude='.git' \
-      --exclude='.release-state' \
-      --exclude='node_modules' \
-      --exclude='.tasks' \
-      --exclude='tmp' \
-      -cf - . | tar -xf - -C "$SANDBOX_DIR"
-
-  release::log_verbose "Copied project files to sandbox"
+  # Try tar pipe first (faster), fallback to cp + rm for portability
+  if tar --exclude='.git' \
+    --exclude='.release-state' \
+    --exclude='node_modules' \
+    --exclude='.tasks' \
+    --exclude='tmp' \
+    -cf - . 2>/dev/null | tar -xf - -C "$SANDBOX_DIR" 2>/dev/null; then
+    release::log_verbose "Copied project files to sandbox (tar)"
+  else
+    # Fallback: traditional cp + rm for maximum portability
+    cp -r . "$SANDBOX_DIR/"
+    rm -rf "$SANDBOX_DIR/.git" "$SANDBOX_DIR/.release-state" \
+      "$SANDBOX_DIR/node_modules" "$SANDBOX_DIR/.tasks" "$SANDBOX_DIR/tmp"
+    release::log_verbose "Copied project files to sandbox (cp)"
+  fi
 }
 
 function release::sandbox::setup_git() {

src/runner.sh

@@ -368,8 +368,8 @@ function bashunit::runner::call_test_functions() {
     done <<<"$(bashunit::helper::get_provider_data "$fn_name" "$script")"
 
     # No data provider found
-    if [[ "$provider_data_count" -eq 0 ]]; then
-      if bashunit::parallel::is_enabled && [[ "$allow_test_parallel" == true ]]; then
+    if [ "$provider_data_count" -eq 0 ]; then
+      if bashunit::parallel::is_enabled && [ "$allow_test_parallel" = true ]; then
         bashunit::runner::run_test "$script" "$fn_name" &
       else
         bashunit::runner::run_test "$script" "$fn_name"
@@ -385,11 +385,11 @@ function bashunit::runner::call_test_functions() {
       parsed_data_count=0
       local line
       while IFS= read -r line; do
-        [[ -z "$line" ]] && continue
+        [ -z "$line" ] && continue
         parsed_data[parsed_data_count]="$(bashunit::helper::decode_base64 "${line}")"
         parsed_data_count=$((parsed_data_count + 1))
       done <<<"$(bashunit::runner::parse_data_provider_args "$data")"
-      if bashunit::parallel::is_enabled && [[ "$allow_test_parallel" == true ]]; then
+      if bashunit::parallel::is_enabled && [ "$allow_test_parallel" = true ]; then
         bashunit::runner::run_test "$script" "$fn_name" ${parsed_data+"${parsed_data[@]}"} &
       else
         bashunit::runner::run_test "$script" "$fn_name" ${parsed_data+"${parsed_data[@]}"}
@@ -399,7 +399,7 @@ function bashunit::runner::call_test_functions() {
   done
 
   # Wait for all parallel tests within this file to complete
-  if bashunit::parallel::is_enabled && [[ "$allow_test_parallel" == true ]]; then
+  if bashunit::parallel::is_enabled && [ "$allow_test_parallel" = true ]; then
     wait
   fi
 }

tests/unit/release_sandbox_test.sh

@@ -8,11 +8,9 @@ if [[ "${BASH_VERSINFO[0]}" -eq 3 ]] && [[ "${BASH_VERSINFO[1]}" -lt 1 ]]; then
 fi
 
 RELEASE_SCRIPT_DIR=""
-FIXTURES_DIR=""
 
 function set_up_before_script() {
   RELEASE_SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
-  FIXTURES_DIR="$(dirname "${BASH_SOURCE[0]}")/fixtures/release"
 
   # Source release.sh to get access to functions
   # shellcheck source=/dev/null

tests/unit/release_update_test.sh

@@ -243,6 +243,7 @@ function test_dry_run_logs_what_would_happen() {
     cd "$temp_dir" || return
     release::update_bashunit_version "0.31.0" 2>&1
   )
+  # shellcheck disable=SC2034
   DRY_RUN=false
 
   assert_contains "DRY-RUN" "$output"

tests/unit/release_validation_test.sh

@@ -8,11 +8,9 @@ if [[ "${BASH_VERSINFO[0]}" -eq 3 ]] && [[ "${BASH_VERSINFO[1]}" -lt 1 ]]; then
 fi
 
 RELEASE_SCRIPT_DIR=""
-FIXTURES_DIR=""
 
 function set_up_before_script() {
   RELEASE_SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
-  FIXTURES_DIR="$(dirname "${BASH_SOURCE[0]}")/fixtures/release"
 
   # Source release.sh to get access to functions
   # shellcheck source=/dev/null