Add support for type checking Container and KeyedContainer. (#8)

* Update IsType.php

* tests `KeyedContainer` and `Container` types

Author: azjezz

src/Constraint/IsType.php

@@ -41,6 +41,8 @@ public static function getTypes(): ImmMap<string, self::TPredicate> {
       'vec' => ($x ==> ($x is vec<_>)),
       'dict' => ($x ==> ($x is dict<_, _>)),
       'keyset' => ($x ==> ($x is keyset<_>)),
+      'Container' => ($x ==> ($x is Container<_>)),
+      'KeyedContainer' => ($x ==> ($x is KeyedContainer<_, _>)),
     };
   }
 

tests/ExpectObjTest.php

@@ -52,6 +52,10 @@ public function testBasicSuccesses(): void {
     expect(vec[])->toNotBeType('array');
     expect(dict[])->toBeType('dict');
     expect(keyset[])->toBeType('keyset');
+    expect(Set {})->toBeType('Container');
+    // vec[] is keyed by int type.
+    expect(vec[])->toBeType('KeyedContainer');
+    expect(dict[])->toBeType('KeyedContainer');
     expect(array(1, 2, 3))->toContain(2);
     expect(array(1, 2, 3))->toNotContain(7);