avoid-misused-test-matchers

added in: 1.12.0

warning

preset: recommended

Warns when an incorrect matcher or literal is used to verify the target expression.

info

This rule supports only matchers provided by the test package.

List of supported matchers

• isNot
• allOf
• anyOf
• isEmpty
• isNotEmpty
• isNull
• isNotNull
• isTrue
• isFalse
• returnsNormally
• prints
• isMap
• isList
• hasLength
• contains
• isIn
• equals
• everyElement
• anyElement
• orderedEquals
• unorderedEquals
• unorderedMatches
• pairwiseCompare
• containsAll
• containsAllInOrder
• containsOnce
• containsValue
• containsPair
• closeTo
• inInclusiveRange
• inExclusiveRange
• inOpenClosedRange
• inClosedOpenRange
• isZero
• isNonZero
• isPositive
• isNonPositive
• isNegative
• isNonNegative
• greaterThan
• greaterThanOrEqualTo
• lessThan
• lessThanOrEqualTo
• equalsIgnoringCase
• equalsIgnoringWhitespace
• startsWith
• endsWith
• stringContainsInOrder
• matches
• isA
• completes
• doesNotComplete
• emitsDone
• emits
• emitsError
• mayEmit
• emitsAnyOf
• emitsInOrder
• emitsThrough
• mayEmitMultiple
• neverEmits
• emitsInAnyOrder
• throwsA
• throwsException
• throwsStateError
• throwsUnimplementedError

Example

❌ Bad:

const _someNumber = 1;
const _someString = '1';
const _someList = [1, 2, 3];

void fn() {
  expect(_someString, isList); // LINT
  expect({1}, isList); // LINT
  expect(_someNumber, isEmpty); // LINT
  expect(_someNumber, isNull); // LINT
  expect(_someNumber, isNotNull); // LINT
  expect(_someNumber, hasLength(1)); // LINT
  expect(_someString, equals(<int>[])); // LINT
  expect(_someString, allOf(isZero, isA<num>())); // LINT
}

✅ Good:

const _someNumber = 1;
const _someString = '1';
const _someList = [1, 2, 3];

void fn() {
  expect(_someString, isA<String>);
  expect(_someList, isList);
  expect(_someNumber, isZero);
  expect(_someList, hasLength(1));
  expect(_someList, contains(1));
}