fix: improve mapEquals to correctly compare maps with different key…

[Danilospano00]

Status

READY

Breaking Changes

NO

Description

The actual version has a bug in mapEquals() that causes false positives when comparing maps with:

• Same length
• Different keys
• At least one null value

🔴 The Bug Explained

Buggy Code

bool mapEquals(Map<Object?, Object?> a, Map<Object?, Object?> b) {
  if (identical(a, b)) return true;
  if (a.length != b.length) return false;
  for (final key in a.keys) {
    if (!objectsEquals(a[key], b[key])) return false;  // ❌ BUG HERE
  }
  return true;
}

The Problem

When you access b[key] and the key doesn't exist in map b, Dart returns null:

final map1 = {'a': 1, 'b': null};
final map2 = {'a': 1, 'c': null};  // 'b' doesn't exist

// Without containsKey:
map1['b']  // = null (explicit)
map2['b']  // = null (missing key!)
objectsEquals(null, null)  // = true ✅
// Result: mapEquals returns TRUE ❌ BUG!

Example with the BUG: User Permissions

class User extends Equatable {
  final Map<String, bool> permissions;
  
  @override
  List<Object> get props => [permissions];
}

final admin = User(permissions: {'read': true, 'write': null});
final guest = User(permissions: {'read': true, 'admin': null});

admin == guest;  // Returns TRUE 
// Admin and guest are treated as equal!

✅ Fix

added !b.containsKey(key)

bool mapEquals(Map<Object?, Object?> a, Map<Object?, Object?> b) {
  if (identical(a, b)) return true;
  if (a.length != b.length) return false;
  for (final key in a.keys) {
    if (!b.containsKey(key) || !objectsEquals(a[key], b[key])) return false;
  }
  return true;
}

[felangel]

Thanks for the fix! I'll get this merged and released shortly and apologies for the delay!

[felangel]

LGTM thanks so much for the fix!