fix(assert): repair the no-perl snapshot placeholder fallback

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 ### Fixed
+- `assert_match_snapshot` placeholders (`::ignore::`) now work on systems without perl: the grep fallback escaped its own wildcard and never matched. Placeholders spanning multiple lines still need perl (grep matches line-by-line)
 - Every run cleans up its run-output scratch directory on exit (test runs, `--version`/`--help`/subcommand exits, and Ctrl-C); previously each invocation leaked one directory under `$TMPDIR/bashunit/run/`. Sourcing errors are captured in that directory too, saving a `mktemp` and an `rm` fork per test file
 - `bashunit::helper::get_function_line_number` no longer disables `extdebug` for its caller: it enables the option only inside a subshell (also dropping an `awk` fork)
 - `--test-timeout` no longer intermittently reports a fast test as timed out; the watchdog now signals by pid and skips a test that already completed

src/assert_snapshot.sh

@@ -71,8 +71,15 @@ function bashunit::snapshot::match_with_placeholder() {
       exit($input =~ /$r/s ? 0 : 1);
     ' && return 0 || return 1
   else
-    local fallback=$(printf '%s' "$snapshot" | sed -e "s|$placeholder|.*|g" -e 's/[][\.^$*+?{}|()]/\\&/g')
-    fallback="^${fallback}$"
+    # No perl: build the pattern exactly like the perl branch — swap the
+    # placeholder for a token that survives escaping, escape the regex
+    # metacharacters, then turn the token into `.*`. (The previous order,
+    # escaping after inserting `.*`, escaped the `.*` itself and broke every
+    # fallback match.) grep matches line-by-line, so unlike the perl branch a
+    # placeholder cannot span multiple lines here.
+    local fallback="${snapshot//$placeholder/$token}"
+    fallback=$(printf '%s' "$fallback" | sed -e 's/[.[\\^$*+?{}()|]/\\&/g')
+    fallback="^${fallback//$token/.*}$"
     echo "$actual" | grep -Eq "$fallback" && return 0 || return 1
   fi
 }

tests/unit/assert_snapshot_test.sh

@@ -157,6 +157,12 @@ function test_snapshot_placeholder_matches_variable_middle() {
 }
 
 function test_snapshot_placeholder_spans_multiple_lines() {
+  # Only the perl matcher can span lines; the grep fallback (e.g. Alpine
+  # without perl) matches line-by-line and documents that limitation.
+  if ! command -v perl >/dev/null 2>&1; then
+    bashunit::skip "multi-line placeholders need perl" && return
+  fi
+
   local snapshot=$'start\n::ignore::\nend'
   local actual=$'start\nanything\nat all\nend'