Merge pull request DefinitelyTyped#8574 from chrootsu/lodash-isWeakSet

lodash: added _.isWeakSet

Author: Igorbek

lodash/lodash-tests.ts

@@ -7201,6 +7201,37 @@ module TestIsWeakMap {
     }
 }
 
+// _.isWeakSet
+module TestIsWeakSet {
+    {
+        let value: number|WeakSet<string>;
+
+        if (_.isWeakSet<string>(value)) {
+            let result: WeakSet<string> = value;
+        }
+        else {
+            let result: number = value;
+        }
+    }
+
+    {
+        let result: boolean;
+
+        result = _.isWeakSet(any);
+        result = _(1).isWeakSet();
+        result = _<any>([]).isWeakSet();
+        result = _({}).isWeakSet();
+    }
+
+    {
+        let result: _.LoDashExplicitWrapper<boolean>;
+
+        result = _(1).chain().isWeakSet();
+        result = _<any>([]).chain().isWeakSet();
+        result = _({}).chain().isWeakSet();
+    }
+}
+
 // _.lt
 module TestLt {
     {

lodash/lodash.d.ts

@@ -12292,6 +12292,31 @@ declare module _ {
         isWeakMap(): LoDashExplicitWrapper<boolean>;
     }
 
+    //_.isWeakSet
+    interface LoDashStatic {
+        /**
+         * Checks if value is classified as a WeakSet object.
+         *
+         * @param value The value to check.
+         * @returns Returns true if value is correctly classified, else false.
+         */
+        isWeakSet<T>(value?: any): value is WeakSet<T>;
+    }
+
+    interface LoDashImplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isWeakSet
+         */
+        isWeakSet(): boolean;
+    }
+
+    interface LoDashExplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isWeakSet
+         */
+        isWeakSet(): LoDashExplicitWrapper<boolean>;
+    }
+
     //_.lt
     interface LoDashStatic {
         /**
@@ -18512,4 +18537,5 @@ declare module "lodash" {
 // Backward compatibility with --target es5
 interface Set<T> {}
 interface Map<K, V> {}
+interface WeakSet<T> {}
 interface WeakMap<K, V> {}