feat(Promise): created Promise never function

README.md

@@ -281,6 +281,27 @@ deepest(c, 'x'); // {x: null} (a)
 
 ### Promise
 
+#### [Never](https://thalesrc.github.io/js-utils/modules/_promise_never_.html)
+A promise which never resolves
+
+```typescript
+import { never, NEVER } from '@thalesrc/js-utils/promise';
+
+function foo(promise = never()) {
+  promise.then(val => {
+    ...
+  });
+}
+
+// or
+
+function foo(promise = NEVER) {
+  promise.then(val => {
+    ...
+  });
+}
+```
+
 #### [Revert](https://thalesrc.github.io/js-utils/modules/_promise_revert_.html)
 Exchanges resolve state with rejection of a promise
 

package.json

@@ -27,7 +27,8 @@
     "unique id",
     "replace",
     "remove",
-    "deepest"
+    "deepest",
+    "never"
   ],
   "repository": {
     "type": "git",

src/promise/index.ts

@@ -1,3 +1,4 @@
+export * from './never';
+export * from './revert';
 export * from './try-catch';
 export * from './timeout';
-export * from './revert';

src/promise/never.spec.ts

@@ -0,0 +1,42 @@
+import 'jest';
+
+import { never, NEVER } from './never';
+import { timeout } from './timeout';
+
+describe('Never Function', () => {
+  it('should not resolve', done => {
+    const foo = never();
+
+    foo.then(() => {
+      throw new Error();
+    }, () => {
+      throw new Error();
+    });
+
+    timeout(50)
+      .then(() => {
+        done();
+      });
+  });
+
+  it('should return the same `NEVER` instance', () => {
+    const foo = never();
+
+    expect(foo).toBe(NEVER);
+  });
+});
+
+describe('Never Constant', () => {
+  it('should not resolve', done => {
+    NEVER.then(() => {
+      throw new Error();
+    }, () => {
+      throw new Error();
+    });
+
+    timeout(50)
+      .then(() => {
+        done();
+      });
+  });
+});

src/promise/never.ts

@@ -0,0 +1,39 @@
+import { noop } from '../function/noop';
+
+/**
+ * A promise which never resolves
+ *
+ * Example:
+ * ```typescript
+ * import { NEVER } from '@thalesrc/js-utils/promise';
+ *
+ * function foo(promise = NEVER) {
+ *   promise.then(val => {
+ *     ...
+ *   });
+ * }
+ * ```
+ */
+export const NEVER = new Promise(noop);
+
+/**
+ * Creates a promise which never resolves
+ *
+ * Example:
+ * ```typescript
+ * import { never } from '@thalesrc/js-utils/promise';
+ *
+ * function foo(promise) {
+ *   promise = promise || never();
+ *
+ *   promise.then(val => {
+ *     ...
+ *   });
+ * }
+ * ```
+ *
+ * @returns the promise which never resolves
+ */
+export function never(): Promise<unknown> {
+  return NEVER;
+}

src/promise/static/never.spec.ts

@@ -0,0 +1,43 @@
+import 'jest';
+
+import './never';
+
+import { timeout } from '../timeout';
+
+describe('Never Function', () => {
+  it('should not resolve', done => {
+    const foo = Promise.never();
+
+    foo.then(() => {
+      throw new Error();
+    }, () => {
+      throw new Error();
+    });
+
+    timeout(50)
+      .then(() => {
+        done();
+      });
+  });
+
+  it('should return the same `NEVER` instance', () => {
+    const foo = Promise.never();
+
+    expect(foo).toBe(Promise.NEVER);
+  });
+});
+
+describe('Never Constant', () => {
+  it('should not resolve', done => {
+    Promise.NEVER.then(() => {
+      throw new Error();
+    }, () => {
+      throw new Error();
+    });
+
+    timeout(50)
+      .then(() => {
+        done();
+      });
+  });
+});

src/promise/static/never.ts

@@ -0,0 +1,44 @@
+import { never, NEVER } from '../never';
+
+declare global {
+  export interface PromiseConstructor {
+    /**
+     * Creates a promise which never resolves
+     *
+     * Example:
+     * ```typescript
+     * import '@thalesrc/js-utils/promise/static/never';
+     *
+     * function foo(promise) {
+     *   promise = promise || Promise.never();
+     *
+     *   promise.then(val => {
+     *     ...
+     *   });
+     * }
+     * ```
+     *
+     * @returns the promise which never resolves
+     */
+    never: typeof never;
+
+    /**
+     * A promise which never resolves
+     *
+     * Example:
+     * ```typescript
+     * import '@thalesrc/js-utils/promise/static/never';
+     *
+     * function foo(promise = Promise.NEVER) {
+     *   promise.then(val => {
+     *     ...
+     *   });
+     * }
+     * ```
+     */
+    NEVER: typeof NEVER;
+  }
+}
+
+Promise.never = never;
+Promise.NEVER = NEVER;