Add ValidatorBuilder

src/ValidatorBuilder.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const constructor = Symbol('constructor');
+
+module.exports = class ValidatorBuilder {
+  /**
+   * Class constructor.
+   *
+   * @type {function}
+   *
+   * @throws {TypeError} If given value is not a function.
+   */
+  set classConstructor(value) {
+    if (typeof value !== 'function') {
+      throw new TypeError(`Class constructor must be a class constructor function, got a ${typeof value} instead`);
+    }
+    this[constructor] = value;
+  }
+
+  /**
+   * Build a validator.
+   *
+   * @param {function} validate - The validation function.
+   *
+   * @returns {Validator} A validator.
+   */
+  build(validate) {
+    const validator = new this[constructor]();
+    validator.validationFunction = validate;
+    return validator;
+  }
+};

test/unit/ValidatorBuilder.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const expect = require('../expect');
+const ValidatorBuilder = require('../../src/ValidatorBuilder');
+
+const builder = new ValidatorBuilder();
+class Validator {}
+
+describe('ValidatorBuilder', () => {
+  describe('"classConstructor" setter', () => {
+    it('shoud accept a function', () => {
+      builder.classConstructor = value => value;
+    });
+
+    it('shoud only accept a function', () => {
+      expect(() => { builder.classConstructor = 'foo'; }).to.throw(TypeError);
+    });
+  });
+
+  describe('"build" method', () => {
+    before(() => {
+      builder.classConstructor = Validator;
+    });
+
+    it('shoud return an instance of classContructor', () => {
+      expect(builder.build()).to.be.an.instanceof(Validator);
+    });
+
+    it('shoud pass first argument to validator validationFunction', () => {
+      expect(builder.build(2)).to.have.property('validationFunction', 2);
+    });
+  });
+});