diff --git a/src/algorithms/string/knuth-morris-pratt/__test__/knuthMorrisPratt.test.js b/src/algorithms/string/knuth-morris-pratt/__test__/knuthMorrisPratt.test.js
index 5b47e72a..42e6f81c 100644
--- a/src/algorithms/string/knuth-morris-pratt/__test__/knuthMorrisPratt.test.js
+++ b/src/algorithms/string/knuth-morris-pratt/__test__/knuthMorrisPratt.test.js
@@ -2,6 +2,9 @@ import knuthMorrisPratt from '../knuthMorrisPratt';
 
 describe('knuthMorrisPratt', () => {
   it('should find word position in given text', () => {
+    expect(knuthMorrisPratt('', '')).toBe(-1);
+    expect(knuthMorrisPratt('a', '')).toBe(-1);
+    expect(knuthMorrisPratt('a', 'a')).toBe(0);
     expect(knuthMorrisPratt('abcbcglx', 'abca')).toBe(-1);
     expect(knuthMorrisPratt('abcbcglx', 'bcgl')).toBe(3);
     expect(knuthMorrisPratt('abcxabcdabxabcdabcdabcy', 'abcdabcy')).toBe(15);