Merge 7043954 into 4307438

README.md

@@ -54,6 +54,7 @@ API
 * [tech](#tech)
 * [layer](#layer)
 * [id](#id)
+* [isBemCell(cell)](#isbemcellcell)
 
 ### constructor(obj)
 
@@ -129,6 +130,26 @@ const cell = new BemCell({
 cell.id; // ➜ "button__text@desktop.css"
 ```
 
+### isBemCell(cell)
+
+Determines whether specified cell is instance of BemCell.
+
+Parameter | Type            | Description
+----------|-----------------|-----------------------
+`cell`    | `BemCell`       | The cell to check.
+
+```js
+const BemCell = require('@bem/cell');
+const BemEntityName = require('@bem/entity-name');
+
+const cell = new BemCell({
+    entity: new BemEntityName({ block: 'button', elem: 'text' })
+});
+
+BemCell.isBemCell(cell); // true
+BemCell.isBemCell({}); // false
+```
+
 License
 -------
 

index.js

@@ -104,4 +104,25 @@ module.exports = class BemCell {
 
         return this._id;
     }
+
+    /**
+     * Determines whether specified cell is instance of BemCell.
+     *
+     * @param {BemCell} cell - the cell to check.
+     *
+     * @returns {boolean} A Boolean indicating whether or not specified entity is instance of BemCell.
+     * @example
+     * const BemCell = require('@bem/cell');
+     * const BemEntityName = require('@bem/entity-name');
+     *
+     * const cell = new BemCell({
+     *     entity: new BemEntityName({ block: 'button', elem: 'text' })
+     * });
+     *
+     * BemCell.isBemCell(cell); // true
+     * BemCell.isBemCell({}); // false
+     */
+    static isBemCell(cell) {
+        return cell && this.name === cell.constructor.name;
+    }
 };

test/is-bem-cell.test.js

@@ -0,0 +1,21 @@
+const test = require('ava');
+const BemEntityName = require('@bem/entity-name');
+
+const BemCell = require('../index');
+
+test('should check valid entities', t => {
+    const cell = new BemCell({
+        entity: new BemEntityName({ block: 'block' })
+    });
+
+    t.true(BemCell.isBemCell(cell));
+});
+
+test('should not pass invalid blocks', t => {
+    t.falsy(BemCell.isBemCell({}));
+    t.falsy(BemCell.isBemCell([]));
+});
+
+test('should not pass null', t => {
+    t.falsy(BemCell.isBemCell(null));
+});