Comprehensive Test Suite Enhancement for Hamming Distance Algorithm

src/test/java/com/thealgorithms/strings/HammingDistanceTest.java

@@ -1,36 +1,69 @@
-package com.thealgorithms.strings;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.stream.Stream;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+	@@ -14,104 +10,62 @@
 import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
 
 class HammingDistanceTest {
 
-    @ParameterizedTest
-    @CsvSource({"'', '', 0", "'java', 'java', 0", "'karolin', 'kathrin', 3", "'kathrin', 'kerstin', 4", "'00000', '11111', 5", "'10101', '10100', 1"})
-    void testHammingDistance(String s1, String s2, int expected) {
-        assertEquals(expected, HammingDistance.calculateHammingDistance(s1, s2));
-    }
+    @Nested
+    @DisplayName("Valid Input Tests")
+    class ValidInputTests {
 
-    @ParameterizedTest
-    @MethodSource("provideNullInputs")
-    void testHammingDistanceWithNullInputs(String input1, String input2) {
-        assertThrows(IllegalArgumentException.class, () -> HammingDistance.calculateHammingDistance(input1, input2));
+        @ParameterizedTest(name = "Hamming distance between \"{0}\" and \"{1}\" should be {2}")
+        @CsvSource({
+            "'', '', 0",
+            "'java', 'java', 0",
+            "'karolin', 'kathrin', 3",
+            "'kathrin', 'kerstin', 4",
+            "'00000', '11111', 5",
+            "'10101', '10100', 1"
+        })
+        void testHammingDistance(String s1, String s2, int expected) {
+            assertEquals(
+                expected,
+                HammingDistance.calculateHammingDistance(s1, s2),
+                String.format("Expected Hamming distance between '%s' and '%s' is %d", s1, s2, expected)
+            );
+        }
     }
 
-    private static Stream<Arguments> provideNullInputs() {
-        return Stream.of(Arguments.of(null, "abc"), Arguments.of("abc", null), Arguments.of(null, null));
-    }
+    @Nested
+    @DisplayName("Invalid Input Tests")
+    class InvalidInputTests {
+
+        @ParameterizedTest(name = "Hamming distance should throw exception for null inputs: \"{0}\", \"{1}\"")
+        @MethodSource("provideNullInputs")
+        void testHammingDistanceWithNullInputs(String input1, String input2) {
+            IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> HammingDistance.calculateHammingDistance(input1, input2),
+                "Expected IllegalArgumentException for null inputs"
+            );
+            assertEquals("Input strings cannot be null", exception.getMessage());
+        }
+
+        private static Stream<Arguments> provideNullInputs() {
+            return Stream.of(
+                Arguments.of(null, "abc"),
+                Arguments.of("abc", null),
+                Arguments.of(null, null)
+            );
+        }
 
-    @Test
-    void testNotEqualStringLengths() {
-        Exception exception = assertThrows(IllegalArgumentException.class, () -> HammingDistance.calculateHammingDistance("ab", "abc"));
-        assertEquals("String lengths must be equal", exception.getMessage());
+        @Test
+        @DisplayName("Should throw exception for unequal string lengths")
+        void testNotEqualStringLengths() {
+            IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> HammingDistance.calculateHammingDistance("ab", "abc"),
+                "Expected IllegalArgumentException for unequal length strings"
+            );
+            assertEquals("String lengths must be equal", exception.getMessage());
+        }
     }
 }