literal_only_boolean_expressions

Boolean expression composed only with literals.

This rule is available as of Dart 2.0.0.

Details

DON’T test for conditions composed only by literals, since the value can be inferred at compile time.

Conditional statements using a condition which cannot be anything but FALSE have the effect of making blocks of code non-functional. If the condition cannot evaluate to anything but true, the conditional statement is completely redundant, and makes the code less readable. It is quite likely that the code does not match the programmer’s intent. Either the condition should be removed or it should be updated so that it does not always evaluate to true or false.

BAD:

void bad() {
  if (true) {} // LINT
}

BAD:

void bad() {
  if (true && 1 != 0) {} // LINT
}

BAD:

void bad() {
  if (1 != 0 && true) {} // LINT
}

BAD:

void bad() {
  if (1 < 0 && true) {} // LINT
}

BAD:

void bad() {
  if (true && false) {} // LINT
}

BAD:

void bad() {
  if (1 != 0) {} // LINT
}

BAD:

void bad() {
  if (true && 1 != 0 || 3 < 4) {} // LINT
}

BAD:

void bad() {
  if (1 != 0 || 3 < 4 && true) {} // LINT
}

NOTE: that an exception is made for the common while (true) { } idiom, which is often reasonably preferred to the equivalent for (;;).

GOOD:

void good() {
  while (true) {
    // Do stuff.
  }
}

Usage

To enable the literal_only_boolean_expressions rule, add literal_only_boolean_expressions under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - literal_only_boolean_expressions