diff --git a/build.gradle b/build.gradle
index 8093152..9f6cd6e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -19,6 +19,11 @@ dependencies {
     implementation 'co.aikar:acf-paper:0.5.0-SNAPSHOT'
     implementation 'org.bstats:bstats-bukkit:1.7'
     compileOnly 'com.destroystokyo.paper:paper-api:1.16.1-R0.1-SNAPSHOT'
+
+    testCompile 'org.assertj:assertj-core:3.15.0'
+    testCompile 'org.junit.jupiter:junit-jupiter-api:5.6.2'
+    testCompile 'org.junit.jupiter:junit-jupiter-params:5.6.2'
+    testCompile 'org.junit.jupiter:junit-jupiter-engine:5.6.2'
 }
 
 processResources {
@@ -49,4 +54,8 @@ checkstyle {
     maxWarnings = 0
 }
 
+test {
+    useJUnitPlatform()
+}
+
 build.dependsOn shadowJar
\ No newline at end of file
diff --git a/src/main/java/net/frankheijden/serverutils/utils/VersionUtils.java b/src/main/java/net/frankheijden/serverutils/utils/VersionUtils.java
index a25005d..934439e 100644
--- a/src/main/java/net/frankheijden/serverutils/utils/VersionUtils.java
+++ b/src/main/java/net/frankheijden/serverutils/utils/VersionUtils.java
@@ -1,7 +1,11 @@
 package net.frankheijden.serverutils.utils;
 
+import java.util.regex.Pattern;
+
 public class VersionUtils {
 
+    private static final Pattern integerPattern = Pattern.compile("[^0-9]");
+
     /**
      * Compares two versions in X.X.X format.
      * Returns true if version is newer than the old one.
@@ -10,13 +14,14 @@ public class VersionUtils {
      * @return true iff new version is newer than old version.
      */
     public static boolean isNewVersion(String oldVersion, String newVersion) {
+        if (oldVersion == null || newVersion == null) return false;
         String[] oldVersionSplit = oldVersion.split("\\.");
         String[] newVersionSplit = newVersion.split("\\.");
 
         int i = 0;
         while (i < oldVersionSplit.length && i < newVersionSplit.length) {
-            int o = Integer.parseInt(oldVersionSplit[i]);
-            int n = Integer.parseInt(newVersionSplit[i]);
+            int o = extractInteger(oldVersionSplit[i]);
+            int n = extractInteger(newVersionSplit[i]);
             if (i != oldVersionSplit.length - 1 && i != newVersionSplit.length - 1) {
                 if (n < o) return false;
             }
@@ -25,4 +30,8 @@ public class VersionUtils {
         }
         return false;
     }
+
+    private static Integer extractInteger(String str) {
+        return Integer.parseInt(integerPattern.matcher(str).replaceAll(""));
+    }
 }
diff --git a/src/test/java/net/frankheijden/serverutils/utils/ListBuilderTest.java b/src/test/java/net/frankheijden/serverutils/utils/ListBuilderTest.java
new file mode 100644
index 0000000..ec4b78f
--- /dev/null
+++ b/src/test/java/net/frankheijden/serverutils/utils/ListBuilderTest.java
@@ -0,0 +1,67 @@
+package net.frankheijden.serverutils.utils;
+
+import static java.util.Arrays.asList;
+import static java.util.Collections.singletonList;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class ListBuilderTest {
+
+    private final String seperator = ", ";
+    private final String lastSeperator = " and ";
+
+    @Test
+    void testToStringOneElement() {
+        String list = ListBuilder.createStrings(singletonList("Nice"))
+                .seperator(seperator)
+                .lastSeperator(lastSeperator)
+                .toString();
+        assertEquals("Nice", list);
+    }
+
+    @Test
+    void testToStringTwoElements() {
+        String list = ListBuilder.createStrings(asList("Nice", "List"))
+                .seperator(seperator)
+                .lastSeperator(lastSeperator)
+                .toString();
+        assertEquals("Nice and List", list);
+    }
+
+    @Test
+    void testToStringMultipleElements() {
+        String list = ListBuilder.createStrings(asList("Nice", "List", "You", "Having", "There"))
+                .seperator(seperator)
+                .lastSeperator(lastSeperator)
+                .toString();
+        assertEquals("Nice, List, You, Having and There", list);
+    }
+
+    @Test
+    void testToStringCustomFormat() {
+        List<TestObject> objects = asList(
+                new TestObject("pre1", 2),
+                new TestObject("pre2", 3),
+                new TestObject("pre3", 4)
+        );
+
+        String list = ListBuilder.create(objects)
+                .format(obj -> obj.prefix + "-" + obj.value)
+                .seperator("; ")
+                .lastSeperator(" and at last ")
+                .toString();
+        assertEquals("pre1-2; pre2-3 and at last pre3-4", list);
+    }
+
+    private static class TestObject {
+        private final String prefix;
+        private final int value;
+
+        public TestObject(String prefix, int value) {
+            this.prefix = prefix;
+            this.value = value;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/net/frankheijden/serverutils/utils/VersionUtilsTest.java b/src/test/java/net/frankheijden/serverutils/utils/VersionUtilsTest.java
new file mode 100644
index 0000000..1b00f96
--- /dev/null
+++ b/src/test/java/net/frankheijden/serverutils/utils/VersionUtilsTest.java
@@ -0,0 +1,42 @@
+package net.frankheijden.serverutils.utils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.of;
+
+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;
+
+class VersionUtilsTest {
+
+    @ParameterizedTest(name = "old = {0}, new = {1}, expected = {2}")
+    @MethodSource("versionGenerator")
+    void isNewVersion(String oldVersion, String newVersion, boolean expected) {
+        assertThat(VersionUtils.isNewVersion(oldVersion, newVersion)).isEqualTo(expected);
+    }
+
+    private static Stream<Arguments> versionGenerator() {
+        return Stream.of(
+                of("0", "1", true),
+                of("1", "0", false),
+                of("9", "10", true),
+                of("10", "9", false),
+                of("-1", "5", true),
+                of("5", "-1", false),
+                of("10.1", "10.0", false),
+                of("100.0", "120.0", true),
+                of("1.0.0", "1.0.1", true),
+                of("1.0.0", "1.1.0", true),
+                of("1.0.0", "2.0.0", true),
+                of("0.0.1", "0.0.1", false),
+                of("0.0.1", "0.0.0", false),
+                of("0.1.0", "0.0.1", false),
+                of("1.0.0", "0.0.1", false),
+                of("1.1.0", "0.1.1", false),
+                of("1.0.0.0", "1.0.0.1", true),
+                of("1.0.1-DEV", "1.0.2", true)
+        );
+    }
+}
\ No newline at end of file