Fixed Test v2

Author: sgindeed

src/test/java/com/thealgorithms/divideandconquer/DeterministicQuickSelectTest.java

@@ -1,6 +1,7 @@
 package com.thealgorithms.divideandconquer;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import org.junit.jupiter.api.Test;
 
@@ -9,41 +10,50 @@ class DeterministicQuickSelectTest {
     @Test
     void testSelectKthSmallestBasic() {
         int[] arr = {7, 10, 4, 3, 20, 15};
-        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 1)); // smallest
+
+        // Test all valid k values
+        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 1));
         assertEquals(4, DeterministicQuickSelect.select(arr.clone(), 2));
         assertEquals(7, DeterministicQuickSelect.select(arr.clone(), 3));
         assertEquals(10, DeterministicQuickSelect.select(arr.clone(), 4));
         assertEquals(15, DeterministicQuickSelect.select(arr.clone(), 5));
-        assertEquals(20, DeterministicQuickSelect.select(arr.clone(), 6)); // largest
+        assertEquals(20, DeterministicQuickSelect.select(arr.clone(), 6));
     }
 
     @Test
-    void testSelectSingleElement() {
+    void testSingleElement() {
         int[] arr = {42};
-        assertEquals(42, DeterministicQuickSelect.select(arr, 1));
+        assertEquals(42, DeterministicQuickSelect.select(arr.clone(), 1));
     }
 
     @Test
-    void testSelectWithDuplicates() {
-        int[] arr = {5, 3, 8, 5, 2, 3};
-        assertEquals(2, DeterministicQuickSelect.select(arr.clone(), 1));
-        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 2));
-        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 3));
-        assertEquals(5, DeterministicQuickSelect.select(arr.clone(), 4));
-        assertEquals(5, DeterministicQuickSelect.select(arr.clone(), 5));
-        assertEquals(8, DeterministicQuickSelect.select(arr.clone(), 6));
+    void testInvalidK() {
+        int[] arr = {1, 2, 3};
+        // k = 0 and k > length should throw IllegalArgumentException
+        assertThrows(IllegalArgumentException.class, () -> DeterministicQuickSelect.select(arr.clone(), 0));
+        assertThrows(IllegalArgumentException.class, () -> DeterministicQuickSelect.select(arr.clone(), 4));
     }
 
     @Test
-    void testSelectEmptyArray() {
-        int[] arr = {};
-        assertThrows(IllegalArgumentException.class, () -> DeterministicQuickSelect.select(arr, 1));
+    void testUnsortedArray() {
+        int[] arr = {12, 3, 5, 7, 4, 19, 26};
+        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 1));
+        assertEquals(4, DeterministicQuickSelect.select(arr.clone(), 2));
+        assertEquals(5, DeterministicQuickSelect.select(arr.clone(), 3));
+        assertEquals(7, DeterministicQuickSelect.select(arr.clone(), 4));
+        assertEquals(12, DeterministicQuickSelect.select(arr.clone(), 5));
+        assertEquals(19, DeterministicQuickSelect.select(arr.clone(), 6));
+        assertEquals(26, DeterministicQuickSelect.select(arr.clone(), 7));
     }
 
     @Test
-    void testSelectInvalidK() {
-        int[] arr = {1, 2, 3};
-        assertThrows(IllegalArgumentException.class, () -> DeterministicQuickSelect.select(arr, 0)); // k < 1
-        assertThrows(IllegalArgumentException.class, () -> DeterministicQuickSelect.select(arr, 4)); // k > length
+    void testArrayWithDuplicates() {
+        int[] arr = {4, 2, 5, 2, 3, 4};
+        assertEquals(2, DeterministicQuickSelect.select(arr.clone(), 1));
+        assertEquals(2, DeterministicQuickSelect.select(arr.clone(), 2));
+        assertEquals(3, DeterministicQuickSelect.select(arr.clone(), 3));
+        assertEquals(4, DeterministicQuickSelect.select(arr.clone(), 4));
+        assertEquals(4, DeterministicQuickSelect.select(arr.clone(), 5));
+        assertEquals(5, DeterministicQuickSelect.select(arr.clone(), 6));
     }
 }