ref: update tests

Author: sozelfist

src/main/java/com/thealgorithms/dynamicprogramming/LevenshteinDistance.java

@@ -9,6 +9,8 @@
  * edits (insertions, deletions, or substitutions) required to change one string into the other.
  */
 public final class LevenshteinDistance {
+    private LevenshteinDistance() {
+    }
 
     /**
      * Calculates the Levenshtein distance between two strings using a naive dynamic programming approach.

src/test/java/com/thealgorithms/dynamicprogramming/LevenshteinDistanceTests.java

@@ -2,23 +2,44 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.ToIntBiFunction;
 import java.util.stream.Stream;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 
 public class LevenshteinDistanceTests {
-    private static final Object[][] TEST_CASES
-        = {{0, "", ""}, {0, "Hello, World!", "Hello, World!"}, {4, "", "Rust"}, {3, "horse", "ros"}, {6, "tan", "elephant"}, {8, "execute", "intention"}, {0, "", ""}, {0, "Hello, World!", "Hello, World!"}, {4, "", "Rust"}, {3, "horse", "ros"}, {6, "tan", "elephant"}, {8, "execute", "intention"}};
 
     @ParameterizedTest
     @MethodSource("testCases")
-    void testLevenshteinDistance(int expectedDistance, String str1, String str2) {
-        assertEquals(expectedDistance, LevenshteinDistance.naiveLevenshteinDistance(str1, str2));
-        assertEquals(expectedDistance, LevenshteinDistance.optimizedLevenshteinDistance(str1, str2));
+    public void testLevenshteinDistance(final int expected, final String str1, final String str2, final ToIntBiFunction<String, String> dist) {
+        assertEquals(expected, dist.applyAsInt(str1, str2));
+        assertEquals(expected, dist.applyAsInt(str2, str1));
+        assertEquals(0, dist.applyAsInt(str1, str1));
+        assertEquals(0, dist.applyAsInt(str2, str2));
     }
 
     private static Stream<Arguments> testCases() {
-        return Stream.of(TEST_CASES).map(args -> Arguments.of(args[0], args[1], args[2]));
+        final Object[][] testData = {
+            {0, "", ""},
+            {0, "Hello, World!", "Hello, World!"},
+            {4, "", "Rust"},
+            {3, "horse", "ros"},
+            {6, "tan", "elephant"},
+            {8, "execute", "intention"},
+            {1, "a", "b"},
+            {1, "a", "aa"},
+            {1, "a", ""},
+            {1, "a", "ab"},
+            {1, "a", "ba"},
+            {2, "a", "bc"},
+            {2, "a", "cb"},
+        };
+
+        final List<ToIntBiFunction<String, String>> methods = Arrays.asList(LevenshteinDistance::naiveLevenshteinDistance, LevenshteinDistance::optimizedLevenshteinDistance);
+
+        return Stream.of(testData).flatMap(input -> methods.stream().map(method -> Arguments.of(input[0], input[1], input[2], method)));
     }
 }