Add mockito

Author: lewisheadden

util/pom.xml

@@ -58,6 +58,12 @@
             <version>4.12</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>2.13.0</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.github.stefanbirkner</groupId>
             <artifactId>system-rules</artifactId>