feat: improve snapshot::match_with_placeholder

Author: Chemaclass

.github/workflows/tests.yml

@@ -131,4 +131,4 @@ jobs:
       - name: Run Tests
         run: |
           docker run --rm -v "$(pwd)":/project -w /project nixos/nix:latest \
-            nix-shell -p bash gnumake git --run "./bashunit --simple tests/"
+            nix-shell -p bash --run "./bashunit --simple tests/"

src/assert_snapshot.sh

@@ -20,6 +20,11 @@ function snapshot::match_with_placeholder() {
     return
   fi
 
+  if grep -P '' </dev/null >/dev/null 2>&1; then
+    printf '%s\0' "$actual" | grep -Pzo "$regex" >/dev/null
+    return
+  fi
+
   # fallback: only supports single-line ignores
   local pattern="${snapshot//$placeholder/.+}"
   pattern=$(printf '%s' "$pattern" | sed -e 's/[][\.^$*+?{}|()]/\\&/g')