Add tests

Author: VincentLanglet

tests/PHPStan/Analyser/nsrt/bug-1452.php

@@ -0,0 +1,9 @@
+<?php declare(strict_types = 1);
+
+namespace Bug1452;
+
+use function PHPStan\Testing\assertType;
+
+$dateInterval = (new \DateTimeImmutable('now -60 minutes'))->diff(new \DateTimeImmutable('now'));
+
+assertType('lowercase-string&non-empty-string&numeric-string&uppercase-string', $dateInterval->format('%a'));

tests/PHPStan/Rules/Operators/InvalidBinaryOperationRuleTest.php

@@ -795,6 +795,13 @@ public function testBenevolentUnion(): void
 		]);
 	}
 
+	public function testBug1452(): void
+	{
+		$this->checkImplicitMixed = true;
+
+		$this->analyse([__DIR__ . '/data/bug-1452.php'], []);
+	}
+
 	public function testBug7863(): void
 	{
 		$this->checkImplicitMixed = true;

tests/PHPStan/Rules/Operators/data/bug-1452.php

@@ -0,0 +1,7 @@
+<?php declare(strict_types = 1);
+
+namespace Bug1452;
+
+$dateInterval = (new \DateTimeImmutable('now -60 minutes'))->diff(new \DateTimeImmutable('now'));
+
+echo $dateInterval->format('%a') * 60;