String Permutation

A permutation is a way of arranging the objects in such a way so that no 2 different arrangements should have the same placement.

package org.wesome.dsalgo;

public class Permutation {
    static int permutationCount = 0;

    public static int permutation(String chosen, String remaining) {
        int remainingLength = remaining.length();
        if (remainingLength == 0) {
            System.out.println("permutation is = " + chosen);
            permutationCount++;
        } else {
            for (int i = 0; i < remainingLength; i++) {
                permutation(chosen + remaining.charAt(i), remaining.substring(0, i) + remaining.substring(i + 1, remainingLength));
            }
        }
        return permutationCount;
    }
}

package org.wesome.dsalgo;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class PermutationTest {
    @Test
    void permutationTest1() {
        Permutation.permutationCount = 0;
        String string = "wesome.org";
        Assertions.assertEquals(3628800, Permutation.permutation("", string));
    }

    @Test
    void permutationTest2() {
        Permutation.permutationCount = 0;
        String string = "1";
        Assertions.assertEquals(1, Permutation.permutation("", string));
    }

    @Test
    void permutationTest3() {
        Permutation.permutationCount = 0;
        String string = "123";
        Assertions.assertEquals(6, Permutation.permutation("", string));
    }
}

plugins {
    id 'java'
}

group = 'org.wesome'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = JavaVersion.VERSION_1_8

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter:5.6.2'
}

test {
    useJUnitPlatform()
}