wip: code formatting nits continued

test/isNaN.spec.js

@@ -0,0 +1,37 @@
+import lodashStable from 'lodash';
+import { falsey, args, slice, symbol, realm } from './utils';
+import isNaN from '../src/isNaN';
+
+describe('isNaN', () => {
+    it('should return `true` for NaNs', () => {
+        expect(isNaN(NaN)).toBe(true);
+        expect(isNaN(Object(NaN))).toBe(true);
+    });
+
+    it('should return `false` for non-NaNs', () => {
+        const expected = lodashStable.map(falsey, (value) => value !== value);
+
+        const actual = lodashStable.map(falsey, (value, index) => (index ? isNaN(value) : isNaN()));
+
+        expect(actual).toEqual(expected);
+
+        expect(isNaN(args)).toBe(false);
+        expect(isNaN([1, 2, 3])).toBe(false);
+        expect(isNaN(true)).toBe(false);
+        expect(isNaN(new Date())).toBe(false);
+        expect(isNaN(new Error())).toBe(false);
+        expect(isNaN(slice)).toBe(false);
+        expect(isNaN({ a: 1 })).toBe(false);
+        expect(isNaN(1)).toBe(false);
+        expect(isNaN(Object(1))).toBe(false);
+        expect(isNaN(/x/)).toBe(false);
+        expect(isNaN('a')).toBe(false);
+        expect(isNaN(symbol)).toBe(false);
+    });
+
+    it('should work with `NaN` from another realm', () => {
+        if (realm.object) {
+            expect(isNaN(realm.nan)).toBe(true);
+        }
+    });
+});