flows-merge (#858)

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* Update core-kotlin-modules/core-kotlin-concurrency-3/src/test/java/com/baeldung/mergemultipleflows/MergeFlowsUnitTest.kt

Co-authored-by: Brandon Ward <[email protected]>

---------

Co-authored-by: Brandon Ward <[email protected]>

Author: kanake10

core-kotlin-modules/core-kotlin-concurrency-3/src/test/java/com/baeldung/mergemultipleflows/MergeFlowsUnitTest.kt

@@ -0,0 +1,75 @@
+package com.baeldung.mergemultipleflows
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.*
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+class FlowMergingTests {
+
+    @Test
+    fun `should merge using the merge function`(): Unit = runBlocking {
+        val flow1 = flowOf(1, 2, 3, 4)
+        val flow2 = flowOf(5, 6, 7, 8)
+        val mergedFlow = merge(flow1, flow2)
+        val result = mergedFlow.toList()
+
+        assertThat(result).containsExactlyInAnyOrder(1, 2, 3, 4, 5, 6, 7, 8)
+    }
+
+    @Test
+    fun `should merge using zip`() = runBlocking {
+        val flow1 = flowOf(1, 2, 3)
+        val flow2 = flowOf("A", "B", "C")
+
+        val result = flow1.zip(flow2) { num, letter ->
+            "$num$letter"
+        }.toList()
+
+        assertEquals(listOf("1A", "2B", "3C"), result)
+    }
+
+
+    @Test
+    fun `should merge using combine`() = runBlocking {
+        val flow1 = flowOf(0)
+        val flow2 = flowOf(1, 2, 3)
+        val result = flow1.combine(flow2) { num1, num2 ->
+            num1 + num2
+        }.toList()
+        assertEquals(listOf(1, 2, 3), result)
+    }
+
+
+
+    @Test
+    fun `should merge using flatmapconcat`() = runBlocking {
+        val flow1 = flowOf(1, 2, 3)
+        val flow2 = flowOf(4, 5, 6)
+        val result = flow1.flatMapConcat { value1 ->
+            flow2.map { value2 -> value1 + value2 }
+        }.toList()
+        assertEquals(listOf(5, 6, 7, 6, 7, 8, 7, 8, 9), result)
+    }
+
+
+    @Test
+    fun `should merge using flatmapmerge`() = runBlocking {
+        val flow1 = flowOf(1, 2, 3)
+        val flow2 = flowOf(4, 5, 6)
+        val result = flow1.flatMapMerge { value1 ->
+            flow2.map { value2 -> value1 + value2 }
+        }.toList()
+        assertEquals(listOf(5, 6, 7, 6, 7, 8, 7, 8, 9), result)
+    }
+
+
+    @Test
+    fun `should merge using runningReduce`() = runBlocking {
+        val result = flowOf(1, 2, 3, 4)
+                .runningReduce { acc, value -> acc + value }
+                .toList()
+        assertEquals(listOf(1, 3, 6, 10), result)
+    }
+}