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avoid-negated-conditions

added in: 1.7.0
style
⚙️🛠
Pro+

Warns when an if statement or conditional expression have a negated condition that can be inverted.

⚙️ Config​

Set ignore-null-checks (default is false) to exclude null checks (example).

analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-negated-conditions:
        ignore-null-checks: false

Example​

❌ Bad:

// LINT: Avoid negated conditions. Try removing the negation and swapping the branches.
if (!flag) {
  ...
} else {
  ...
}

// LINT: Avoid negated conditions. Try removing the negation and swapping the branches.
if (flag is! bool) {
  ...
} else {
  ...
}

// LINT: Avoid negated conditions. Try removing the negation and swapping the branches.
final newValue = !flag ? value - 1 : value + 1;

✅ Good:

if (flag) { // Correct, no negated condition
  ...
} else {
  ...
}

if (flag is bool) {
  ...
} else {
  ...
}

final newValue = flag ? value + 1 : value - 1;

Example with "ignore-null-checks"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-negated-conditions:
        ignore-null-checks: false

✅ Good:

int? value = 1;

void fn() {
  if (value != null) { // Correct, null checks are ignored
  } else {}

  if (value == null) {
  } else {}
}