Add test case for GH-8964

Author: derickr

NEWS

@@ -8,6 +8,8 @@ PHP                                                                        NEWS
 - Date:
   . Fixed bug GH-8730 (DateTime::diff miscalculation is same time zone of
     different type). (Derick)
+  . Fixed bug GH-8964 (DateTime object comparison after applying delta less
+    than 1 second). (Derick)
   . Fixed bug #81263 (Wrong result from DateTimeImmutable::diff). (Derick)
 
 - DBA:

ext/date/tests/bug-gh8964-001.phpt

@@ -0,0 +1,25 @@
+--TEST--
+Test for bug GH-8964: DateTime object comparison after applying delta less than 1 second
+--INI--
+date.timezone=UTC
+--FILE--
+<?php
+$actual = new DateTimeImmutable("2022-07-21 15:00:10");
+$delta    = new \DateInterval(sprintf('PT%dS', 0));
+$delta->f = 0.9;
+
+$expectedLower = $actual->sub($delta);
+$expectedUpper = $actual->add($delta);
+
+echo $expectedLower->format( 'H:i:s.u U' ), "\n";
+echo $actual       ->format( 'H:i:s.u U' ), "\n";
+echo $expectedUpper->format( 'H:i:s.u U' ), "\n";
+
+var_dump($actual < $expectedLower, $actual > $expectedUpper);
+?>
+--EXPECTF--
+15:00:09.100000 1658415609
+15:00:10.000000 1658415610
+15:00:10.900000 1658415610
+bool(false)
+bool(false)

ext/date/tests/bug-gh8964-002.phpt

@@ -0,0 +1,38 @@
+--TEST--
+Test for bug GH-8964: DateTime object comparison after applying delta less than 1 second
+--INI--
+date.timezone=UTC
+--FILE--
+<?php
+for ($seconds = 0; $seconds < 3; $seconds++)
+{
+	$actual   = new DateTimeImmutable("2022-07-21 15:00:10");
+	$delta    = new \DateInterval(sprintf('PT%dS', $seconds));
+	$delta->f = -0.9;
+
+	$expectedLower = $actual->sub($delta);
+	$expectedUpper = $actual->add($delta);
+
+	echo $expectedLower->format( 'H:i:s.u U' ), "\n";
+	echo $actual       ->format( 'H:i:s.u U' ), "\n";
+	echo $expectedUpper->format( 'H:i:s.u U' ), "\n";
+
+	var_dump($actual < $expectedLower, $actual > $expectedUpper);
+}
+?>
+--EXPECTF--
+15:00:10.900000 1658415610
+15:00:10.000000 1658415610
+15:00:09.100000 1658415609
+bool(true)
+bool(true)
+15:00:09.900000 1658415609
+15:00:10.000000 1658415610
+15:00:10.100000 1658415610
+bool(false)
+bool(false)
+15:00:08.900000 1658415608
+15:00:10.000000 1658415610
+15:00:11.100000 1658415611
+bool(false)
+bool(false)