Merge remote-tracking branch 'origin/2.13' into 2.14

Author: dinomite

release-notes/CREDITS-2.x

@@ -13,6 +13,9 @@ Authors:
 
 Contributors:
 
+Stefan Schmid (schmist@github)
+* #519: Contributed test for #518 (null should deserialize to _the_ Unit instance)
+
 wrongwrong (k163377@github)
 * #456: Refactor KNAI.findImplicitPropertyName()
 * #449: Refactor AnnotatedMethod.hasRequiredMarker()

src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/github/failing/Github518.kt

@@ -0,0 +1,47 @@
+package com.fasterxml.jackson.module.kotlin.test.github.failing
+
+import com.fasterxml.jackson.module.kotlin.KotlinFeature.SingletonSupport
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import com.fasterxml.jackson.module.kotlin.jsonMapper
+import com.fasterxml.jackson.module.kotlin.kotlinModule
+import com.fasterxml.jackson.module.kotlin.readValue
+import com.fasterxml.jackson.module.kotlin.test.expectFailure
+import kotlin.test.assertSame
+import org.junit.Test
+
+/**
+ * An empty object should be deserialized as *the* Unit instance for a nullable Unit reference Type.
+ */
+class TestGithub518 {
+
+    /**
+     * Empty object did not serialize to the singleton Unit before 2.13 as described in
+     * https://github.com/FasterXML/jackson-module-kotlin/issues/196.
+     */
+    @Test
+    fun deserializeEmptyObjectToSingletonUnit() {
+        assertSame(jacksonObjectMapper().readValue<Unit>("{}"), Unit)
+    }
+
+    /**
+     * Empty object does not serialize to the singleton Unit for a nullable reference Type as described in
+     * https://github.com/FasterXML/jackson-module-kotlin/issues/518.
+     */
+    @Test
+    fun deserializeEmptyObjectToSingletonUnitFails() {
+        expectFailure<AssertionError>("GitHub #518 has been fixed!") {
+            assertSame(jacksonObjectMapper().readValue<Unit?>("{}"), Unit)
+        }
+    }
+
+    /**
+     * Empty object serializes to the singleton Unit for a nullable reference if singleton support is enabled. Is this
+     * setting really required to deserialize Unit correctly or should it also work correctly without singleton support
+     * enabled?
+     */
+    @Test
+    fun deserializeEmptyObjectToSingletonUnitWithSingletonSupport() {
+        val objectMapper = jsonMapper { addModule(kotlinModule { configure(SingletonSupport, true) }) }
+        assertSame(objectMapper.readValue<Unit?>("{}"), Unit)
+    }
+}