Added more test cases

Author: Anubhav-pandey004

src/test/java/com/thealgorithms/slidingwindow/MinimumWindowSubstringTest.java

@@ -19,5 +19,13 @@ public void testMinimumWindowSubstring() {
         assertEquals("BANC", MinimumWindowSubstring.minWindow("ADOBECODEBANC", "ABC")); // "BANC"
         assertEquals("a", MinimumWindowSubstring.minWindow("a", "a")); // "a"
         assertEquals("", MinimumWindowSubstring.minWindow("a", "aa")); // ""
+        assertEquals("", MinimumWindowSubstring.minWindow("ADOBECODEBANC", "XYZ")); 
+        assertEquals("BC", MinimumWindowSubstring.minWindow("ABCDEF", "BC"));
+        assertEquals("CODE", MinimumWindowSubstring.minWindow("ADOBECODEBANC", "CODE")); 
+        assertEquals("q", MinimumWindowSubstring.minWindow("abcdefghijklmnopqrstuvwxyz", "q"));
+        assertEquals("JQTUHzRLPPyjllmvqopolorblqrijdpytjzxxvnyqihohrszawlvetnrgcnrknuandawlfzthoeoeiqsxliroreemjvqfzuimacidfymmpyljzxtwatvqszhtsjsmpgzjozxvcygidhsunqtvlbvamafbjmplrbrehjmvvlxyluuaqgbrmfxrygeylkzlflbfcwqnemigwhrrshdqiwvifoifxsaxfyqnibcwrkffbtjqxjubgrfvexqhocdvyyavdmujnfwwecqkantiaogsrgvwtwwkcczydpevynzvirsppgrdmfhbdtczprkrrvxxlxjcvauaharesmqjxhjwmrrtspsbobgofrnvdzbwiibqhrrqbtxyspnszwpxbqrwtavsmhhqrqkjegvhbeftfbicnhamhwyonlwlzysocyzshhyknbdkelplkkvazqpnzhydraoyiodssA", MinimumWindowSubstring.minWindow("HRULTrctorlsshmgtarxadgosylsmxsorskzqfdkujoJQTUHzRLPPyjllmvqopolorblqrijdpytjzxxvnyqihohrszawlvetnrgcnrknuandawlfzthoeoeiqsxliroreemjvqfzuimacidfymmpyljzxtwatvqszhtsjsmpgzjozxvcygidhsunqtvlbvamafbjmplrbrehjmvvlxyluuaqgbrmfxrygeylkzlflbfcwqnemigwhrrshdqiwvifoifxsaxfyqnibcwrkffbtjqxjubgrfvexqhocdvyyavdmujnfwwecqkantiaogsrgvwtwwkcczydpevynzvirsppgrdmfhbdtczprkrrvxxlxjcvauaharesmqjxhjwmrrtspsbobgofrnvdzbwiibqhrrqbtxyspnszwpxbqrwtavsmhhqrqkjegvhbeftfbicnhamhwyonlwlzysocyzshhyknbdkelplkkvazqpnzhydraoyiodssA", "HRULTPQPJA")); 
+        assertEquals("", MinimumWindowSubstring.minWindow("zzzzzzzzz", "zzzzzzzzzz")); 
+        assertEquals("ABCDEFAAAllBBBBllZ", MinimumWindowSubstring.minWindow("ABCllBBBBBlllllllABCDEFAAAllBBBBllZ", "ABAAACDEFZ")); 
+        assertEquals("abbbbbcdd", MinimumWindowSubstring.minWindow("aaaaaaaaaaaabbbbbcdd", "abcdd")); 
     }
 }