refactor: ReverseString, test improvements (#5406)

* refactor: ReverseString

* refactor: refactor testing into two methods

* checkstyle: fix formatting

* checkstyle: fix formatting

---------

Co-authored-by: alxkm <[email protected]>

Author: alxkm

src/main/java/com/thealgorithms/strings/ReverseString.java

@@ -7,11 +7,6 @@ public final class ReverseString {
     private ReverseString() {
     }
 
-    public static void main(String[] args) {
-        assert reverse("abc123").equals("321cba");
-        assert reverse2("abc123").equals("321cba");
-    }
-
     /**
      * easiest way to reverses the string str and returns it
      *

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

@@ -2,30 +2,27 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import org.junit.jupiter.api.Test;
+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 ReverseStringTest {
 
-    @Test
-    public void testReverseString() {
-        String input1 = "Hello World";
-        String input2 = "helloworld";
-        String input3 = "123456789";
-        String input4 = "";
-
-        String expectedOutput1 = "dlroW olleH";
-        String expectedOutput2 = "dlrowolleh";
-        String expectedOutput3 = "987654321";
-        String expectedOutput4 = "";
+    private static Stream<Arguments> testCases() {
+        return Stream.of(Arguments.of("Hello World", "dlroW olleH"), Arguments.of("helloworld", "dlrowolleh"), Arguments.of("123456789", "987654321"), Arguments.of("", ""), Arguments.of("A", "A"), Arguments.of("ab", "ba"),
+            Arguments.of("  leading and trailing spaces  ", "  secaps gniliart dna gnidael  "), Arguments.of("!@#$%^&*()", ")(*&^%$#@!"), Arguments.of("MixOf123AndText!", "!txeTdnA321fOxiM"));
+    }
 
-        assertEquals(ReverseString.reverse(input1), expectedOutput1);
-        assertEquals(ReverseString.reverse(input2), expectedOutput2);
-        assertEquals(ReverseString.reverse(input3), expectedOutput3);
-        assertEquals(ReverseString.reverse(input4), expectedOutput4);
+    @ParameterizedTest
+    @MethodSource("testCases")
+    public void testReverseString(String input, String expectedOutput) {
+        assertEquals(expectedOutput, ReverseString.reverse(input));
+    }
 
-        assertEquals(ReverseString.reverse2(input1), expectedOutput1);
-        assertEquals(ReverseString.reverse2(input2), expectedOutput2);
-        assertEquals(ReverseString.reverse2(input3), expectedOutput3);
-        assertEquals(ReverseString.reverse2(input4), expectedOutput4);
+    @ParameterizedTest
+    @MethodSource("testCases")
+    public void testReverseString2(String input, String expectedOutput) {
+        assertEquals(expectedOutput, ReverseString.reverse2(input));
     }
 }