typescript(option): test: wrote tests for isNone

Signed-off-by: prescientmoon <git@moonythm.dev>

typescript/option/src/helpers/isNone.test.ts

@@ -0,0 +1,22 @@
+import { expect } from 'chai'
+import { isNone } from './isNone'
+import { None } from '../types'
+import { someX } from '../../test/constants'
+
+describe('The isNone helper', () => {
+    it('should return false when given Some', () => {
+        // act
+        const result = isNone(someX)
+
+        // assert
+        expect(result).to.equal(false)
+    })
+
+    it('should return true when given None', () => {
+        // act
+        const result = isNone(None)
+
+        // assert
+        expect(result).to.equal(true)
+    })
+})