Fix multipleOf bugs (#114)

* Fix bug when using multipleOf values with decimal places
* Allow resetting multipleOf back to null
* Add tests for multipleOf bugs
* Fix incorrect formatting of multipleOf in error message

- `%d` casts the multipleOf to a whole number even if its a float with decimals
- `%f` would add unnecessary decimals, e.g. `0.01` would become `0.010000`
- `%s` maintains the same number of decimals, e.g. `0.01` stays `0.01`

---------

Co-authored-by: bertramakers <[email protected]>

src/Schema/Type/Number.php

@@ -50,8 +50,16 @@ public function validate(mixed $value, callable $fail): void
             }
         }
 
-        if ($this->multipleOf !== null && $value % $this->multipleOf !== 0) {
-            $fail(sprintf('must be a multiple of %d', $this->multipleOf));
+        // Divide the value by multipleOf instead of using the modulo operator to avoid bugs when using a multipleOf
+        // that has decimal places. (Since the modulo operator converts the multipleOf to int)
+        // Note that dividing two integers returns another integer if the result is a whole number. So to make the
+        // comparison work at all times we need to cast the result to float. Casting both to integer will not work
+        // as intended since then the result of the division would also be rounded.
+        if (
+            $this->multipleOf !== null &&
+            (float) ($value / $this->multipleOf) !== round($value / $this->multipleOf)
+        ) {
+            $fail(sprintf('must be a multiple of %s', $this->multipleOf));
         }
     }
 
@@ -85,7 +93,7 @@ public function maximum(?float $maximum, bool $exclusive = false): static
 
     public function multipleOf(?float $number): static
     {
-        if ($number <= 0) {
+        if ($number !== null && $number <= 0) {
             throw new InvalidArgumentException('multipleOf must be a positive number');
         }
 

tests/unit/NumberTest.php

@@ -40,6 +40,10 @@ public static function validationProvider(): array
             [Number::make()->maximum(10, exclusive: true), 10, false],
             [Number::make()->multipleOf(2), 1, false],
             [Number::make()->multipleOf(2), 2, true],
+            [Number::make()->multipleOf(0.01), 100, true],
+            [Number::make()->multipleOf(0.01), 100.5, true],
+            [Number::make()->multipleOf(0.01), 100.56, true],
+            [Number::make()->multipleOf(0.01), 100.567, false],
         ];
     }
 
@@ -56,4 +60,16 @@ public function test_validation(Type $type, mixed $value, bool $valid)
 
         $type->validate($value, $fail);
     }
+
+    public function test_multipleOf_reset(): void
+    {
+        $number = Number::make()
+            ->multipleOf(2)
+            ->multipleOf(null);
+
+        $fail = $this->createMock(MockedCaller::class);
+        $fail->expects($this->never())->method('__invoke');
+
+        $number->validate(5, $fail);
+    }
 }