refactor: clarify shell mode handling in main and runner

    - Add explanatory comment in main.sh for why set +euo pipefail is needed
    - Handle both strict and permissive modes explicitly in runner.sh

Author: Chemaclass

src/main.sh

@@ -143,9 +143,11 @@ function bashunit::main::cmd_test() {
     exec >/dev/null 2>&1
   fi
 
+  # Disable strict mode for test execution to allow:
+  # - Empty array expansion (set +u)
+  # - Non-zero exit codes from failing tests (set +e)
+  # - Pipe failures in test output (set +o pipefail)
   set +euo pipefail
-
-  # Execute
   if [[ -n "$assert_fn" ]]; then
     bashunit::main::exec_assert "$assert_fn" "${args[@]}"
   else

src/runner.sh

@@ -405,9 +405,11 @@ function bashunit::runner::run_test() {
       exit $setup_exit_code
     fi
 
-    # Apply strict mode setting for test execution
+    # Apply shell mode setting for test execution
     if bashunit::env::is_strict_mode_enabled; then
       set -euo pipefail
+    else
+      set +euo pipefail
     fi
 
     # 2>&1: Redirects the std-error (FD 2) to the std-output (FD 1).