add test case for Github #56

src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/Github56.kt

@@ -0,0 +1,77 @@
+package com.fasterxml.jackson.module.kotlin.test
+
+import com.fasterxml.jackson.annotation.JsonInclude
+import com.fasterxml.jackson.annotation.JsonUnwrapped
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException
+import com.fasterxml.jackson.module.kotlin.*
+import org.junit.Before
+import org.junit.Test
+import kotlin.test.assertEquals
+
+private data class TestGalleryWidget_BAD(
+        val widgetReferenceId: String,
+        @JsonUnwrapped var gallery: TestGallery
+)
+
+private data class TestGalleryWidget_GOOD(val widgetReferenceId: String) {
+    @JsonUnwrapped lateinit var gallery: TestGallery
+}
+
+
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
+private data class TestGallery(
+        val id: String? = null,
+        val headline: String? = null,
+        val intro: String? = null,
+        val role: String? = null,
+        val images: List<TestImage>? = null
+)
+
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
+private data class TestImage(
+        val id: String? = null,
+        val escenicId: String? = null,
+        val caption: String? = null,
+        val copyright: String? = null,
+        val crops: Map<String, String>? = null
+)
+
+class Github56 {
+    lateinit var mapper: ObjectMapper
+
+    private val gallery = TestGallery(
+            id = "id",
+            headline = "headline",
+            intro = "intro",
+            role = "role",
+            images = listOf(
+                    TestImage(id = "testImage1"),
+                    TestImage(id = "testImage2")
+            )
+    )
+    val validJson = """
+         {"widgetReferenceId":"widgetReferenceId","id":"id","headline":"headline","intro":"intro","role":"role","images":[{"id":"testImage1"},{"id":"testImage2"}]}
+    """.trim()
+
+    @Before
+    fun setUp() {
+        mapper = jacksonObjectMapper()
+    }
+
+    @Test
+    fun serializes() {
+        val result = mapper.writeValueAsString(TestGalleryWidget_BAD("widgetReferenceId", gallery))
+        assertEquals(validJson, result)
+    }
+
+    @Test(expected = InvalidDefinitionException::class)
+    fun deserializesWithError() {
+        mapper.readValue<TestGalleryWidget_BAD>(validJson)
+    }
+
+    @Test
+    fun deserializesCorrectly() {
+        mapper.readValue<TestGalleryWidget_GOOD>(validJson)
+    }
+}