Enhancement: Implement Specification::never()

CHANGELOG.md

@@ -15,6 +15,7 @@ For a full diff see [`3.1.0...3.0.0`][2.1.0...3.0.0].
 ## Added
 
 - Added `Specification::closure()` ([#56]), by [@localheinz]
+- Added `Specification::never()` ([#57]), by [@localheinz]
 
 ## [`3.0.0`][3.0.0]
 
@@ -87,5 +88,6 @@ For a full diff see [`a5ba52c...1.0.0`][a5ba52c...1.0.0].
 [#48]: https://github.com/ergebnis/json-pointer/pull/48
 [#53]: https://github.com/ergebnis/json-pointer/pull/53
 [#56]: https://github.com/ergebnis/json-pointer/pull/56
+[#57]: https://github.com/ergebnis/json-pointer/pull/57
 
 [@localheinz]: https://github.com/localheinz

README.md

@@ -243,6 +243,20 @@ $specification = Pointer\Specification::equals(Pointer\JsonPointer::fromJsonStri
 $specification->isSatisfiedBy(Pointer\JsonPointer::fromJsonString('/foo'));     // false
 $specification->isSatisfiedBy(Pointer\JsonPointer::fromJsonString('/foo/bar')); // true
 ```
+You can create a `Specification` that is never satisfied by a `JsonPointer`:
+
+```php
+<?php
+
+declare(strict_types=1);
+
+use Ergebnis\Json\Pointer;
+
+$specification = Pointer\Specification::never();
+
+$specification->isSatisfiedBy(Pointer\JsonPointer::fromJsonString('/foo'));     // false
+$specification->isSatisfiedBy(Pointer\JsonPointer::fromJsonString('/foo/bar')); // false
+```
 
 You can compose `Specification`s to find out if a `JsonPointer` satisfies any of them:
 
@@ -258,6 +272,7 @@ $specification = Pointer\Specification::anyOf(
         return $jsonPointer->toJsonString() === '/foo/bar';
     }),
     Pointer\Specification::equals(Pointer\JsonPointer::fromJsonString('/foo/baz')),
+    Pointer\Specification::never(),
 );
 
 $specification->isSatisfiedBy(Pointer\JsonPointer::fromJsonString('/foo'));     // false

src/Specification.php

@@ -62,4 +62,11 @@ public static function equals(JsonPointer $other): self
             return $jsonPointer->equals($other);
         });
     }
+
+    public static function never(): self
+    {
+        return new self(static function (): bool {
+            return false;
+        });
+    }
 }

test/Unit/SpecificationTest.php

@@ -108,4 +108,13 @@ public function testEqualsIsSatisfiedByJsonPointerWhenJsonPointerEqualsOther():
 
         self::assertTrue($specification->isSatisfiedBy($jsonPointer));
     }
+
+    public function testNeverIsNotSSatisfiedByAnyJsonPointer(): void
+    {
+        $jsonPointer = JsonPointer::fromJsonString('/foo/bar');
+
+        $specification = Specification::never();
+
+        self::assertFalse($specification->isSatisfiedBy($jsonPointer));
+    }
 }