@@ -2,14 +2,21 @@
 
 namespace PHPStan\Rules\PHPUnit;
 
+use Countable;
 use PhpParser\Node;
 use PhpParser\Node\Expr\CallLike;
 use PhpParser\Node\Expr\MethodCall;
 use PhpParser\Node\Expr\StaticCall;
 use PhpParser\Node\Identifier;
+use PhpParser\Node\Scalar\Int_;
+use PhpParser\Node\Scalar\String_;
 use PHPStan\Analyser\Scope;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\UnionType;
+use function array_merge;
 use function count;
 use function in_array;
 use function sprintf;
@@ -43,11 +50,83 @@ public function processNode(Node $node, Scope $scope): array
 			return [];
 		}
 
+		$errorBuilder = RuleErrorBuilder::message(sprintf('%s() is not allowed. Use more strict assertion.', $node->name->toString()))
+			->identifier('phpunit.assertEmpty');
+
+		if (AssertRuleHelper::hasNamedOrUnpackedArguments($node)) {
+			return [$errorBuilder->build()];
+		}
+
+		$replacement = $this->getReplacement($scope->getNativeType($node->getArgs()[0]->value), $node->name->toLowerString() === 'assertnotempty');
+		if ($replacement !== null) {
+			[$correctName, $expectedValue] = $replacement;
+			$errorBuilder->fixNode($node, static function (CallLike $node) use ($correctName, $expectedValue) {
+				$node->name = new Identifier($correctName);
+				if ($expectedValue !== null) {
+					$node->args = array_merge([new Node\Arg($expectedValue)], $node->args);
+				}
+
+				return $node;
+			});
+		}
+
 		return [
-			RuleErrorBuilder::message(sprintf('%s() is not allowed. Use more strict assertion.', $node->name->toString()))
-				->identifier('phpunit.assertEmpty')
-				->build(),
+			$errorBuilder->build(),
 		];
 	}
 
+	/**
+	 * @return array{string, Node\Expr|null}|null
+	 */
+	private function getReplacement(Type $type, bool $negated): ?array
+	{
+		if ($type instanceof UnionType) {
+			if (TypeCombinator::containsNull($type)) {
+				$typeWithoutNull = TypeCombinator::removeNull($type);
+
+				$classReflections = $typeWithoutNull->getObjectClassReflections();
+				if (count($classReflections) === 0) {
+					return null;
+				}
+				foreach ($classReflections as $classReflection) {
+					if (
+						$classReflection->isBuiltin()
+						|| !$classReflection->isFinalByKeyword()
+						|| $classReflection->implementsInterface(Countable::class)
+					) {
+						return null;
+					}
+
+					$parentClass = $classReflection->getParentClass();
+					while ($parentClass !== null) {
+						// Builtin parents can define different empty() semantics.
+						if ($parentClass->isBuiltin()) {
+							return null;
+						}
+						$parentClass = $parentClass->getParentClass();
+					}
+				}
+
+				return [$negated ? 'assertNotNull' : 'assertNull', null];
+			}
+
+			return null;
+		}
+
+		if ($type->isBoolean()->yes()) {
+			return [$negated ? 'assertTrue' : 'assertFalse', null];
+		}
+		if ($type->isArray()->yes()) {
+			return [$negated ? 'assertNotCount' : 'assertCount', new Int_(0)];
+		}
+		if ($type->isInteger()->yes()) {
+			return [$negated ? 'assertNotSame' : 'assertSame', new Int_(0)];
+		}
+		if ($type->isNonFalsyString()->yes()) {
+			return [$negated ? 'assertNotSame' : 'assertSame', new String_('')];
+		}
+
+		return null;
+	}
+
 }
@@ -4,6 +4,7 @@
 
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<AssertEmptyIsDiscouragedRule>
@@ -21,6 +22,20 @@ public function testRule(): void
 		]);
 	}
 
+	public function testFix(): void
+	{
+		$this->fix(__DIR__ . '/data/assert-empty-is-discouraged-fixable.php', __DIR__ . '/data/assert-empty-is-discouraged-fixable.php.fixed');
+	}
+
+	public function testNativeUnionTypeIsNotFixed(): void
+	{
+		if (PHP_VERSION_ID < 80000) {
+			self::markTestSkipped('Native union types require PHP 8.0.');
+		}
+
+		$this->fix(__DIR__ . '/data/assert-empty-is-discouraged-native-union.php', __DIR__ . '/data/assert-empty-is-discouraged-native-union.php.fixed');
+	}
+
 	protected function getRule(): Rule
 	{
 		return new AssertEmptyIsDiscouragedRule();
 
@@ -0,0 +1,143 @@
+<?php declare(strict_types = 1);
+
+namespace AssertEmptyIsDiscouragedFixTest;
+
+use PHPUnit\Framework\Assert;
+use PHPUnit\Framework\TestCase;
+
+final class UserDefinedObject
+{
+
+}
+
+/** @final */
+class PhpDocFinalObject
+{
+
+}
+
+class UserDefinedCountable implements \Countable
+{
+
+	public function count(): int
+	{
+		return 0;
+	}
+
+}
+
+class OpenParent
+{
+
+}
+
+interface Thing
+{
+
+}
+
+class ThingImplementation implements Thing, \Countable
+{
+
+	public function count(): int
+	{
+		return 0;
+	}
+
+}
+
+final class FinalEmptyIterator extends \EmptyIterator
+{
+
+}
+
+final class FinalCountable implements \Countable
+{
+
+	public function count(): int
+	{
+		return 0;
+	}
+
+}
+
+final class AssertEmptyTest extends TestCase
+{
+
+	/**
+	 * @param non-falsy-string $nonFalsyString
+	 * @param non-falsy-string $otherNonFalsyString
+	 * @param int $phpDocInteger
+	 * @param string|int $union
+	 */
+	public function test(
+		array $arguments,
+		bool $boolean,
+		array $array,
+		int $integer,
+		float $float,
+		string $string,
+		$union,
+		string $nonFalsyString,
+		string $otherNonFalsyString,
+		?\stdClass $nullableObject,
+		?object $otherNullableObject,
+		?\SimpleXMLElement $nullableSimpleXml,
+		?UserDefinedObject $nullableUserDefinedObject,
+		?UserDefinedObject $otherNullableUserDefinedObject,
+		?PhpDocFinalObject $nullablePhpDocFinalObject,
+		?UserDefinedCountable $nullableCountable,
+		?OpenParent $nullableOpenParent,
+		?Thing $nullableThing,
+		?FinalEmptyIterator $nullableEmptyIterator,
+		?FinalCountable $nullableFinalCountable,
+		$phpDocInteger,
+		$mixed
+	): void
+	{
+		$this->assertEmpty(...$arguments);
+		$this->assertEmpty($boolean);
+		$this->assertNotEmpty($boolean);
+		$this->assertEmpty($array, 'message');
+		$this->assertNotEmpty($array);
+		$this->assertEmpty($integer);
+		$this->assertNotEmpty($integer);
+		Assert::assertEmpty($float);
+		Assert::assertNotEmpty($float);
+		$this->assertEmpty($nonFalsyString);
+		$this->assertNotEmpty($otherNonFalsyString);
+		$this->assertEmpty($string);
+		$this->assertNotEmpty($string);
+		$this->assertEmpty($union);
+		$this->assertNotEmpty($union);
+		$this->assertEmpty($nullableObject);
+		$this->assertNotEmpty($otherNullableObject);
+		$this->assertEmpty($nullableSimpleXml);
+		$this->assertEmpty($nullableUserDefinedObject);
+		$this->assertNotEmpty($otherNullableUserDefinedObject);
+		$this->assertEmpty($nullablePhpDocFinalObject);
+		$this->assertNotEmpty($nullablePhpDocFinalObject);
+		$this->assertEmpty($nullableCountable);
+		$this->assertNotEmpty($nullableCountable);
+		$this->assertEmpty($nullableOpenParent);
+		$this->assertNotEmpty($nullableOpenParent);
+		$this->assertEmpty($nullableThing);
+		$this->assertNotEmpty($nullableThing);
+		$this->assertEmpty($nullableEmptyIterator);
+		$this->assertNotEmpty($nullableEmptyIterator);
+		$this->assertEmpty($nullableFinalCountable);
+		$this->assertNotEmpty($nullableFinalCountable);
+		$this->assertNotEmpty($phpDocInteger);
+		$this->assertEmpty($mixed);
+	}
+
+	public function testNativeNonFalsyString(string $value): void
+	{
+		if ($value === '' || $value === '0') {
+			return;
+		}
+
+		$this->assertNotEmpty($value);
+	}
+
+}