Return 'just now' for zero-second differences (#500)

When diffForHumans() is called on two identical timestamps, return
"just now" instead of the awkward "0 seconds ago".

This provides a more natural, human-readable output for edge cases
where two times are effectively the same.

Author: dereuromark

src/DifferenceFormatter.php

@@ -96,6 +96,11 @@ public function diffForHumans(
                 $unit = 'second';
                 break;
         }
+
+        if ($count === 0 && $unit === 'second') {
+            return $this->translate->singular('just_now');
+        }
+
         $time = $this->translate->plural($unit, $count, ['count' => $count]);
         if ($absolute) {
             return $time;

src/Translator.php

@@ -40,6 +40,7 @@ class Translator
         'minute_plural' => '{count} minutes',
         'second' => '1 second',
         'second_plural' => '{count} seconds',
+        'just_now' => 'just now',
         'ago' => '{time} ago',
         'from_now' => '{time} from now',
         'after' => '{time} after',

tests/TestCase/Date/DiffTest.php

@@ -350,14 +350,14 @@ public function testDiffForHumansWithNowAbsolute()
     public function testDiffForHumansWithoutDiff()
     {
         $this->wrapWithTestNow(function () {
-            $this->assertSame('0 seconds ago', ChronosDate::parse(Chronos::now())->diffForHumans());
+            $this->assertSame('just now', ChronosDate::parse(Chronos::now())->diffForHumans());
         });
     }
 
     public function testDiffForHumansWithoutDiffAbsolute()
     {
         $this->wrapWithTestNow(function () {
-            $this->assertSame('0 seconds', ChronosDate::parse(Chronos::now())->diffForHumans(null, true));
+            $this->assertSame('just now', ChronosDate::parse(Chronos::now())->diffForHumans(null, true));
         });
     }
 }

tests/TestCase/DateTime/DiffTest.php

@@ -612,14 +612,14 @@ public function testDiffForHumansWithNowAbsolute()
     public function testDiffForHumansWithoutDiff()
     {
         $this->wrapWithTestNow(function () {
-            $this->assertSame('0 seconds ago', Chronos::now()->diffForHumans());
+            $this->assertSame('just now', Chronos::now()->diffForHumans());
         });
     }
 
     public function testDiffForHumansWithoutDiffAbsolute()
     {
         $this->wrapWithTestNow(function () {
-            $this->assertSame('0 seconds', Chronos::now()->diffForHumans(null, true));
+            $this->assertSame('just now', Chronos::now()->diffForHumans(null, true));
         });
     }