1 files changed, 39 insertions, 0 deletions
diff --git a/kotlinx-coroutines-core/common/test/flow/operators/FlattenConcatTest.kt b/kotlinx-coroutines-core/common/test/flow/operators/FlattenConcatTest.kt
new file mode 100644
index 00000000..084af5b9
--- /dev/null
+++ b/kotlinx-coroutines-core/common/test/flow/operators/FlattenConcatTest.kt
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.coroutines.flow
+
+import kotlinx.coroutines.*
+import kotlin.test.*
+
+class FlattenConcatTest : FlatMapBaseTest() {
+
+    override fun <T> Flow<T>.flatMap(mapper: suspend (T) -> Flow<T>): Flow<T> = map(mapper).flattenConcat()
+
+    @Test
+    fun testFlatMapConcurrency() = runTest {
+        var concurrentRequests = 0
+        val flow = (1..100).asFlow().map { value ->
+            flow {
+                ++concurrentRequests
+                emit(value)
+                delay(Long.MAX_VALUE)
+            }
+        }.flattenConcat()
+
+        val consumer = launch {
+            flow.collect { value ->
+                expect(value)
+            }
+        }
+
+        repeat(4) {
+            yield()
+        }
+
+        assertEquals(1, concurrentRequests)
+        consumer.cancelAndJoin()
+        finish(2)
+    }
+}