Add a config property to ignore unknown properties for all API calls.

This is especially useful to make sure fields added to the XML API by
BGG do not crash the client.

src/main/kotlin/org/audux/bgg/BggClient.kt

@@ -954,14 +954,17 @@ object BggClient {
  * @property retryMaxDelayMs see kdoc for formula
  * @property retryRandomizationMs see kdoc for formula
  * @property requestTimeoutMillis At which point requests time out/throw an time out Exception.
+ * @property failOnUnknownProperties whether BGGClient should fail when it encounters unknown
+ *   properties or if it should parse what it can for the given api.
  */
 data class BggClientConfiguration(
     var maxConcurrentRequests: Int = 10,
     var maxRetries: Int = 5,
     var retryBase: Double = 2.0,
     var retryMaxDelayMs: Long = 60_000,
     var retryRandomizationMs: Long = 1_000,
-    var requestTimeoutMillis: Long = 15_000
+    var requestTimeoutMillis: Long = 15_000,
+    var failOnUnknownProperties: Boolean = true,
 )
 
 /** Thrown whenever any exception is thrown during a request to BGG. */

src/main/kotlin/org/audux/bgg/InternalBggClient.kt

@@ -87,7 +87,10 @@ internal class InternalBggClient {
         XmlMapper.builder()
             .apply {
                 configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true)
-                configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true)
+                configure(
+                    DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,
+                    BggClient.configuration.failOnUnknownProperties
+                )
 
                 addModule(JacksonXmlModule())
                 addModule(JavaTimeModule())

src/test/kotlin/org/audux/bgg/BggClientTest.kt

@@ -13,11 +13,14 @@ import io.ktor.http.HttpStatusCode
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.CountDownLatch
 import kotlinx.coroutines.runBlocking
+import org.audux.bgg.request.things
 import org.audux.bgg.response.Response
 import org.audux.bgg.util.TestUtils
 import org.audux.bgg.util.TestUtils.delayedResponse
+import org.audux.bgg.util.TestUtils.setupMockEngine
 import org.junit.jupiter.api.AfterEach
 import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.params.ParameterizedTest
@@ -196,6 +199,41 @@ class BggClientTest {
         }
     }
 
+    @Nested
+    inner class UnknownProperty {
+        @Test
+        fun `fails parsing an unknown property`() = runBlocking {
+            BggClient.configure { failOnUnknownProperties = true }
+            BggClient.engine = { setupMockEngine("thing?id=with-unknown-property") }
+
+            val response = BggClient.things(ids = arrayOf(1)).call()
+
+            assertThat(response.data).isNull()
+            assertThat(response.error)
+                .isEqualTo(
+                    "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" +
+                        "<items termsofuse=\"https://boardgamegeek.com/xmlapi/termsofuse\">\n" +
+                        "    <item><unkown>Exception</unkown></item>\n" +
+                        "</items>"
+                )
+
+            BggClient.configure { failOnUnknownProperties = true }
+        }
+
+        @Test
+        fun `parses an item wih an unknown field`() = runBlocking {
+            BggClient.configure { failOnUnknownProperties = false }
+            BggClient.engine = { setupMockEngine("thing?id=with-unknown-property") }
+
+            val response = BggClient.things(ids = arrayOf(1)).call()
+
+            assertThat(response.data).isNotNull()
+            assertThat(response.error).isNull()
+
+            BggClient.configure { failOnUnknownProperties = true }
+        }
+    }
+
     private fun testRetryConfiguration(config: BggClientConfiguration) =
         config.apply {
             retryBase = 1.0

src/test/resources/xml/thing?id=with-unknown-property.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<items termsofuse="https://boardgamegeek.com/xmlapi/termsofuse">
+    <item><unkown>Exception</unkown></item>
+</items>