[print-array-in-1-line] print array elements in one line (#774)

Author: sk1418

core-kotlin-modules/core-kotlin-arrays-2/src/test/kotlin/com/baeldung/printAllElementsInOneLine/PrintAllElementsInOneLineUnitTest.kt

@@ -0,0 +1,80 @@
+package com.baeldung.printAllElementsInOneLine
+
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import java.io.ByteArrayOutputStream
+import java.io.PrintStream
+import kotlin.test.assertEquals
+
+
+class PrintAllElementsInOneLineUnitTest {
+    val myArray = arrayOf("A", "B", "C", "D", "E", "F")
+    val arrayWithComma = arrayOf("A", "B, C", "D, E", "F")
+
+    val newLine = System.lineSeparator()
+    val stdOut = System.out
+    val myOutput = ByteArrayOutputStream()
+
+    @BeforeEach
+    fun setup() {
+        System.setOut(PrintStream(myOutput))
+    }
+
+    @AfterEach
+    fun restore() {
+        System.setOut(stdOut)
+    }
+
+
+    @Test
+    fun `when using myOutput then we can verify println() result`() {
+        println("Hello, world")
+        assertEquals("Hello, world$newLine", myOutput.toString())
+
+        myOutput.reset()
+
+        println("Kotlin rocks")
+        assertEquals("Kotlin rocks$newLine", myOutput.toString())
+    }
+
+    @Test
+    fun `when converting array to list then all elements are in one line`() {
+        println(myArray.asList())
+        assertEquals("[A, B, C, D, E, F]$newLine", myOutput.toString())
+
+        myOutput.reset()
+
+        println(arrayWithComma.asList())
+        // cannot customize the output format
+        assertEquals("[A, B, C, D, E, F]$newLine", myOutput.toString())
+    }
+
+
+    @Test
+    fun `when using print() then get the expected result`() {
+        myArray.forEachIndexed { idx, e ->
+            print(if (idx == myArray.lastIndex) "$e$newLine" else "$e, ")
+        }
+        assertEquals("A, B, C, D, E, F$newLine", myOutput.toString())
+
+        myOutput.reset()
+
+        arrayWithComma.forEachIndexed { idx, e ->
+            print(if (idx == arrayWithComma.lastIndex) """"$e"$newLine""" else """"$e", """)
+        }
+        assertEquals(""""A", "B, C", "D, E", "F"$newLine""", myOutput.toString())
+    }
+
+    @Test
+    fun `when using joinToString() then get the expected result`() {
+        println(myArray.joinToString { it })
+        assertEquals("A, B, C, D, E, F$newLine", myOutput.toString())
+
+        myOutput.reset()
+
+        println(arrayWithComma.joinToString { """"$it"""" })
+        assertEquals(""""A", "B, C", "D, E", "F"$newLine""", myOutput.toString())
+    }
+
+}