Refactor - adding different scala object detecting

src/main/scala/com/fasterxml/jackson/module/scala/deser/ScalaObjectDeserializerModule.scala

@@ -1,31 +1,27 @@
 package com.fasterxml.jackson.module.scala.deser
 
 import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind._
 import com.fasterxml.jackson.databind.deser.Deserializers
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer
-import com.fasterxml.jackson.databind._
 import com.fasterxml.jackson.module.scala.JacksonModule
-import com.fasterxml.jackson.module.scala.util.ClassW
+import com.fasterxml.jackson.module.scala.util.ScalaObject
 
 import scala.languageFeature.postfixOps
-import scala.util.control.NonFatal
 
-private class ScalaObjectDeserializer(clazz: Class[_]) extends StdDeserializer[Any](classOf[Any]) {
-  override def deserialize(p: JsonParser, ctxt: DeserializationContext): Any = {
-    try {
-      clazz.getField("MODULE$").get(null)
-    } catch {
-      case NonFatal(_) => null
-    }
-  }
+private class ScalaObjectDeserializer(scalaObject: Any) extends StdDeserializer[Any](classOf[Any]) {
+  override def deserialize(p: JsonParser, ctxt: DeserializationContext): Any = scalaObject
 }
 
 private object ScalaObjectDeserializerResolver extends Deserializers.Base {
   override def findBeanDeserializer(javaType: JavaType, config: DeserializationConfig, beanDesc: BeanDescription): JsonDeserializer[_] = {
     val clazz = javaType.getRawClass
-    if (ClassW(clazz).isScalaObject)
-      new ScalaObjectDeserializer(clazz)
-    else null
+
+    Option(clazz)
+      .collect {
+        case ScalaObject(value) => new ScalaObjectDeserializer(value)
+      }
+      .orNull
   }
 }
 

src/main/scala/com/fasterxml/jackson/module/scala/util/ScalaObject.scala

@@ -0,0 +1,29 @@
+package com.fasterxml.jackson.module.scala.util
+
+import java.lang.reflect.Field
+
+object ScalaObject {
+
+  private val MODULE_FIELD_NAME = "MODULE$"
+
+  private def getStaticField(field: Field): Option[Any] =
+    try Some(field.get(null))
+    catch {
+      case _: NullPointerException | _: IllegalAccessException => None
+    }
+
+  private def moduleFieldOption(clazz: Class[_]): Option[Field] =
+    try Some(clazz.getDeclaredField(MODULE_FIELD_NAME))
+    catch {
+      case _: NoSuchFieldException => None
+    }
+
+  private def moduleFieldValue(clazz: Class[_]): Option[Any] = for {
+    moduleField <- moduleFieldOption(clazz)
+    value <- getStaticField(moduleField)
+  } yield value
+
+  def unapply(clazz: Class[_]): Option[Any] =
+    if (clazz.getSimpleName.endsWith("$")) moduleFieldValue(clazz)
+    else None
+}

src/test/scala-2.+/com/fasterxml/jackson/module/scala/util/ScalaObjectTest.scala

@@ -0,0 +1,53 @@
+package com.fasterxml.jackson.module.scala.util
+
+import org.scalatest.matchers.should.Matchers.{contain, convertToAnyShouldWrapper, empty}
+import org.scalatest.wordspec.AnyWordSpecLike
+
+object TestObject
+
+case object TestCaseObject
+
+class TestClass
+
+class TestClassWithModuleField {
+  val MODULE$: TestClassWithModuleField = this
+}
+
+class TestClass$
+
+class TestClassWithModuleField$ {
+  val MODULE$: TestClassWithModuleField$ = this
+}
+
+class ScalaObjectTest extends AnyWordSpecLike {
+
+  "ScalaObject" must {
+    "return Some(TestObject) for unapply(TestObject.getClass)" in {
+      ScalaObject.unapply(TestObject.getClass) should contain(TestObject)
+    }
+
+    "return Some(TestCaseObject) for unapply(TestCaseObject.getClass)" in {
+      ScalaObject.unapply(TestCaseObject.getClass) should contain(TestCaseObject)
+    }
+
+    "return None for unapply(testClassInstance.getClass)" in {
+      val testClassInstance = new TestClass
+      ScalaObject.unapply(testClassInstance.getClass) shouldBe empty
+    }
+
+    "return None for unapply(testClassWithModuleFieldInstance.getClass)" in {
+      val testClassWithModuleFieldInstance = new TestClassWithModuleField
+      ScalaObject.unapply(testClassWithModuleFieldInstance.getClass) shouldBe empty
+    }
+
+    "return None for unapply(testClassWithADollarInstance.getClass)" in {
+      val testClassWithADollarInstance = new TestClass$
+      ScalaObject.unapply(testClassWithADollarInstance.getClass) shouldBe empty
+    }
+
+    "return None for unapply(testClassWithModuleFieldAndADollarInstance.getClass)" in {
+      val testClassWithModuleFieldAndADollarInstance = new TestClassWithModuleField$
+      ScalaObject.unapply(testClassWithModuleFieldAndADollarInstance.getClass) shouldBe empty
+    }
+  }
+}