Add unit tests for areas plugin

game/plugin/areas/src/AreaActionBuilder.kt

@@ -0,0 +1,42 @@
+package org.apollo.game.plugins.area
+
+/**
+ * A builder for ([Area], [AreaAction]) [Pair]s.
+ */
+class AreaActionBuilder internal constructor(val name: String, val area: Area) {
+
+    private var entrance: AreaListener = { }
+
+    private var inside: AreaListener = { }
+
+    private var exit: AreaListener = { }
+
+    /**
+     * Places the contents of this builder into an ([Area], [AreaAction]) [Pair].
+     */
+    internal fun build(): Pair<Area, AreaAction> {
+        return Pair(area, AreaAction(entrance, inside, exit))
+    }
+
+    /**
+     * The [listener] to execute when a player enters the associated [Area].
+     */
+    fun entrance(listener: AreaListener) {
+        this.entrance = listener
+    }
+
+    /**
+     * The [listener] to execute when a player moves around inside the associated [Area].
+     */
+    fun inside(listener: AreaListener) {
+        this.inside = listener
+    }
+
+    /**
+     * The [listener] to execute when a player moves exits the associated [Area].
+     */
+    fun exit(listener: AreaListener) {
+        this.exit = listener
+    }
+
+}