Add boolean validator (#13)

source/lib/predicates/boolean.ts

@@ -0,0 +1,28 @@
+import { Predicate, Context } from './predicate';
+
+export class BooleanPredicate extends Predicate<boolean> {
+
+	constructor(context?: Context) {
+		super('boolean', context);
+	}
+
+	/**
+	 * Test a boolean to be true.
+	 */
+	get true() {
+		return this.addValidator({
+			message: value => `Expected ${value} to be true`,
+			validator: value => value === true
+		});
+	}
+
+	/**
+	 * Test a boolean to be false.
+	 */
+	get false() {
+		return this.addValidator({
+			message: value => `Expected ${value} to be false`,
+			validator: value => value === false
+		});
+	}
+}

source/ow.ts

@@ -2,6 +2,7 @@ import { ArgumentError } from './lib/argument-error';
 import { Predicate, validatorSymbol } from './lib/predicates/predicate';
 import { StringPredicate } from './lib/predicates/string';
 import { NumberPredicate } from './lib/predicates/number';
+import { BooleanPredicate } from './lib/predicates/boolean';
 
 export interface Ow {
 	(value: any, predicate: Predicate): void;
@@ -13,6 +14,10 @@ export interface Ow {
 	 * Test the value to be a number.
 	 */
 	number: NumberPredicate;
+	/**
+	 * Test the value to be a boolean.
+	 */
+	boolean: BooleanPredicate;
 }
 
 const main = (value: any, predicate: Predicate) => {
@@ -30,6 +35,9 @@ Object.defineProperties(main, {
 	},
 	number: {
 		get: () => new NumberPredicate()
+	},
+	boolean: {
+		get: () => new BooleanPredicate()
 	}
 });
 

source/test/boolean.ts

@@ -0,0 +1,23 @@
+import test from 'ava';
+import * as m from '..';
+
+test('boolean', t => {
+	t.notThrows(() => m(true, m.boolean));
+	t.throws(() => m('12', m.boolean), 'Expected argument to be of type `boolean` but received type `string`');
+});
+
+test('boolean.true', t => {
+	t.notThrows(() => m(true, m.boolean.true));
+	t.notThrows(() => m(Boolean(true), m.boolean.true));
+	t.notThrows(() => m(Boolean(1), m.boolean.true));
+	t.throws(() => m(false, m.boolean.true), 'Expected false to be true');
+	t.throws(() => m(Boolean(0), m.boolean.true), 'Expected false to be true');
+});
+
+test('boolean.false', t => {
+	t.notThrows(() => m(false, m.boolean.false));
+	t.notThrows(() => m(Boolean(false), m.boolean.false));
+	t.notThrows(() => m(Boolean(0), m.boolean.false));
+	t.throws(() => m(true, m.boolean.false), 'Expected true to be false');
+	t.throws(() => m(Boolean(1), m.boolean.false), 'Expected true to be false');
+});

tslint.json

@@ -70,7 +70,7 @@
 		"newline-before-return": true,
 		"new-parens": true,
 		"no-angle-bracket-type-assertion": true,
-		"no-boolean-literal-compare": true,
+		"no-boolean-literal-compare": false,
 		"no-consecutive-blank-lines": true,
 		"no-irregular-whitespace": true,
 		"no-reference-import": true,