fix tests

src/Expectation.php

@@ -374,11 +374,11 @@ final class Expectation
     /**
      * Asserts that the value is one of the given values.
      *
-     * @param array<int, int|string> $possibleValues
+     * @param iterable<int|string, mixed> $values
      */
-    public function toBeIn(array $possibleValues): Expectation
+    public function toBeIn(iterable $values): Expectation
     {
-        Assert::assertContains($this->value, $possibleValues);
+        Assert::assertContains($this->value, $values);
 
         return $this;
     }

tests/Features/Expect/toBeIn.php

@@ -4,8 +4,13 @@ use PHPUnit\Framework\ExpectationFailedException;
 
 test('passes', function () {
     expect('a')->toBeIn(['a', 'b', 'c']);
+    expect('d')->not->toBeIn(['a', 'b', 'c']);
 });
 
 test('failures', function () {
     expect('d')->toBeIn(['a', 'b', 'c']);
 })->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect('a')->not->toBeIn(['a', 'b', 'c']);
+})->throws(ExpectationFailedException::class);