From 4609833da146beafe839682d7558edf9f64c96fc Mon Sep 17 00:00:00 2001
From: Fahim Faisaal <fahimfaisal.soikot@gmail.com>
Date: Thu, 17 Feb 2022 10:31:34 +0600
Subject: [PATCH] test: add four new test cases

---
 String/test/Lower.test.js | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/String/test/Lower.test.js b/String/test/Lower.test.js
index 0fbaaa5d6..527a8a07d 100644
--- a/String/test/Lower.test.js
+++ b/String/test/Lower.test.js
@@ -1,9 +1,19 @@
 import { lower } from '../Lower'
 
-describe('Lower', () => {
-  it('return uppercase strings', () => {
-    expect(lower('hello')).toBe('hello')
-    expect(lower('WORLD')).toBe('world')
-    expect(lower('hello_WORLD')).toBe('hello_world')
+describe('Testing the Lower function', () => {
+  it('Test 1: Check by invalid type', () => {
+    expect(() => lower(345)).toThrowError();
+    expect(() => lower(true)).toThrowError();
+    expect(() => lower(null)).toThrowError();
+  })
+
+  it('Test 2: Check by uppercase string', () => {
+    expect(lower('WORLD')).toBe('world');
+    expect(lower('Hello_WORLD')).toBe('hello_world');
+  })
+
+  it('Test 3: Check by lowercase string', () => {
+    expect(lower('hello')).toBe('hello');
+    expect(lower('hello_world')).toBe('hello_world');
   })
 })