Add dataView, NaN, and nullOrUndefined predicates (#38)

package.json

@@ -47,7 +47,7 @@
 		"object"
 	],
 	"devDependencies": {
-		"@sindresorhus/is": "^0.6.0",
+		"@sindresorhus/is": "^0.7.0",
 		"@types/highlight.js": "^9.12.2",
 		"@types/node": "^8.0.31",
 		"add-module-exports-webpack-plugin": "^0.1.0",

source/index.ts

@@ -36,6 +36,14 @@ export interface Ow {
 	 * Test the value to be null.
 	 */
 	readonly null: Predicate<null>;
+	/**
+	 * Test the value to be null or undefined.
+	 */
+	readonly nullOrUndefined: Predicate<null | undefined>;
+	/**
+	 * Test the value to be not a number.
+	 */
+	readonly nan: Predicate<number>;
 	/**
 	 * Test the value to be a Symbol.
 	 */
@@ -120,6 +128,10 @@ export interface Ow {
 	 * Test the value to be a ArrayBuffer.
 	 */
 	readonly arrayBuffer: Predicate<ArrayBuffer>;
+	/**
+	 * Test the value to be a DataView.
+	 */
+	readonly dataView: Predicate<DataView>;
 	/**
 	 * Test the value to be Iterable.
 	 */
@@ -151,6 +163,12 @@ Object.defineProperties(main, {
 	null: {
 		get: () => new Predicate('null')
 	},
+	nullOrUndefined: {
+		get: () => new Predicate('nullOrUndefined')
+	},
+	nan: {
+		get: () => new Predicate('nan')
+	},
 	symbol: {
 		get: () => new Predicate('symbol')
 	},
@@ -214,6 +232,9 @@ Object.defineProperties(main, {
 	arrayBuffer: {
 		get: () => new Predicate('arrayBuffer')
 	},
+	dataView: {
+		get: () => new Predicate('dataView')
+	},
 	iterable: {
 		get: () => new Predicate('iterable')
 	}

source/test/data-view.ts

@@ -0,0 +1,8 @@
+import test from 'ava';
+import m from '..';
+
+test('dataView', t => {
+	t.notThrows(() => m(new DataView(new ArrayBuffer(1)), m.dataView));
+	t.throws(() => m(new ArrayBuffer(1) as any, m.dataView), 'Expected argument to be of type `dataView` but received type `ArrayBuffer`');
+	t.throws(() => m(12 as any, m.dataView), 'Expected argument to be of type `dataView` but received type `number`');
+});

source/test/nan.ts

@@ -0,0 +1,10 @@
+import test from 'ava';
+import m from '..';
+
+test('nan', t => {
+	t.notThrows(() => m(NaN, m.nan));
+	t.notThrows(() => m(Number.NaN, m.nan));
+	t.notThrows(() => m(0 / 0, m.nan));
+	t.throws(() => m(12, m.nan), 'Expected argument to be of type `nan` but received type `number`');
+	t.throws(() => m('12' as any, m.nan), 'Expected argument to be of type `nan` but received type `string`');
+});

source/test/null-or-undefined.ts

@@ -0,0 +1,13 @@
+import test from 'ava';
+import m from '..';
+
+test('nullOrUndefined', t => {
+	const x = null;
+	const y = undefined;
+
+	t.notThrows(() => m(null, m.nullOrUndefined));
+	t.notThrows(() => m(undefined, m.nullOrUndefined));
+	t.notThrows(() => m(x, m.nullOrUndefined));
+	t.notThrows(() => m(y, m.nullOrUndefined));
+	t.throws(() => m('foo' as any, m.nullOrUndefined), 'Expected argument to be of type `nullOrUndefined` but received type `string`');
+});