From 0ee6991d6851da323bb5dcaf607605450a7e56bf Mon Sep 17 00:00:00 2001
From: "Stuebinger, Bernd" <stuebingerb@mediamarktsaturn.com>
Date: Fri, 28 May 2021 12:10:43 +0200
Subject: [PATCH] Fix issue 34 for coroutines

---
 ...dUpdateOrReplaceOrDeleteCouldReturnNull.kt | 46 +++++++++++++++++++
 .../kmongo/coroutine/CoroutineCollection.kt   |  2 +-
 2 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 kmongo-coroutine-core-tests/src/main/kotlin/org/litote/kmongo/coroutine/issues/Issue34FindOneAndUpdateOrReplaceOrDeleteCouldReturnNull.kt

diff --git a/kmongo-coroutine-core-tests/src/main/kotlin/org/litote/kmongo/coroutine/issues/Issue34FindOneAndUpdateOrReplaceOrDeleteCouldReturnNull.kt b/kmongo-coroutine-core-tests/src/main/kotlin/org/litote/kmongo/coroutine/issues/Issue34FindOneAndUpdateOrReplaceOrDeleteCouldReturnNull.kt
new file mode 100644
index 00000000..02540fe9
--- /dev/null
+++ b/kmongo-coroutine-core-tests/src/main/kotlin/org/litote/kmongo/coroutine/issues/Issue34FindOneAndUpdateOrReplaceOrDeleteCouldReturnNull.kt
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2016/2021 Litote
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.litote.kmongo.coroutine.issues
+
+import kotlinx.coroutines.runBlocking
+import org.junit.Test
+import org.litote.kmongo.MongoOperator.set
+import org.litote.kmongo.coroutine.KMongoReactiveStreamsCoroutineBaseTest
+import org.litote.kmongo.model.Friend
+import kotlin.test.assertNull
+
+/**
+ *
+ */
+class Issue34FindOneAndUpdateOrReplaceOrDeleteCouldReturnNull : KMongoReactiveStreamsCoroutineBaseTest<Friend>() {
+
+    @Test
+    fun findOneAndReplaceCouldReturnNull() = runBlocking {
+        assertNull(col.findOneAndReplace("{}", Friend("test")))
+    }
+
+    @Test
+    fun findOneAndUpdateCouldReturnNull() = runBlocking {
+        assertNull(col.findOneAndUpdate("{}", "{$set:{name:'John'}}"))
+    }
+
+    @Test
+    fun findOneAndDeleteCouldReturnNull() = runBlocking {
+        assertNull(col.findOneAndDelete("{}"))
+    }
+
+}
diff --git a/kmongo-coroutine-core/src/main/kotlin/org/litote/kmongo/coroutine/CoroutineCollection.kt b/kmongo-coroutine-core/src/main/kotlin/org/litote/kmongo/coroutine/CoroutineCollection.kt
index 044818a6..15a765d8 100644
--- a/kmongo-coroutine-core/src/main/kotlin/org/litote/kmongo/coroutine/CoroutineCollection.kt
+++ b/kmongo-coroutine-core/src/main/kotlin/org/litote/kmongo/coroutine/CoroutineCollection.kt
@@ -707,7 +707,7 @@ class CoroutineCollection<T : Any>(val collection: MongoCollection<T>) {
         filter: Bson,
         replacement: T,
         options: FindOneAndReplaceOptions = FindOneAndReplaceOptions()
-    ): T = collection.findOneAndReplace(filter, replacement, options).awaitSingle()
+    ): T? = collection.findOneAndReplace(filter, replacement, options).awaitFirstOrNull()
 
     /**
      * Atomically find a document and replace it.