TASK: Union test that all members are deduplicated

Author: mhsdesign

src/TypeSystem/Type/UnionType/UnionType.php

@@ -25,12 +25,15 @@
 use PackageFactory\ComponentEngine\TypeSystem\Type\NullType\NullType;
 use PackageFactory\ComponentEngine\TypeSystem\TypeInterface;
 
-final class UnionType implements TypeInterface
+/**
+ * @implements \IteratorAggregate<int, TypeInterface>
+ */
+final class UnionType implements TypeInterface, \IteratorAggregate, \Countable
 {
     /**
      * @var TypeInterface[]
      */
-    private array $members;
+    private readonly array $members;
 
     private function __construct(TypeInterface ...$members)
     {
@@ -57,7 +60,7 @@ public static function of(TypeInterface ...$members): TypeInterface
             return $uniqueMembers[0];
         }
 
-        return new self(...$members);
+        return new self(...$uniqueMembers);
     }
 
     public function isNullable(): bool
@@ -107,4 +110,15 @@ public function is(TypeInterface $other): bool
             return false;
         }
     }
+
+    /** @return \ArrayIterator<int, TypeInterface> */
+    public function getIterator(): \ArrayIterator
+    {
+        return new \ArrayIterator($this->members);
+    }
+
+    public function count(): int
+    {
+        return count($this->members);
+    }
 }

test/Unit/TypeSystem/Type/UnionType/UnionTypeTest.php

@@ -87,6 +87,27 @@ public function isReturnsTrueIfGivenTypeIsCongruentUnionTypeWithRedundantMembers
         $this->assertTrue($unionType->is($otherUnionType));
     }
 
+    /**
+     * @test
+     */
+    public function unionOnlyHoldsDeduplicatedMembers(): void
+    {
+        $unionType = UnionType::of(NumberType::get(), StringType::get());
+        $otherUnionType = UnionType::of(NumberType::get(), StringType::get(), NumberType::get(), StringType::get());
+
+        $this->assertTrue($unionType->is($otherUnionType));
+
+        $this->assertInstanceOf(UnionType::class, $unionType);
+        $this->assertInstanceOf(UnionType::class, $otherUnionType);
+
+        $this->assertCount(count($unionType), $otherUnionType);
+
+        $this->assertEqualsCanonicalizing(
+            $unionType->getIterator()->getArrayCopy(),
+            $otherUnionType->getIterator()->getArrayCopy()
+        );
+    }
+
     /**
      * @test
      */
@@ -97,4 +118,4 @@ public function isReturnsFalseIfGivenTypeIsNotCongruent(): void
         $this->assertFalse($unionType->is(NumberType::get()));
         $this->assertFalse($unionType->is(StringType::get()));
     }
-}
+}