Merge pull request #6674 from CROSP/inputstream-to-string-in-kotlin

BAEL-2654 InputStream to String in Kotlin

core-kotlin-2/src/main/kotlin/com/baeldung/inputstream/InputStreamExtension.kt

@@ -0,0 +1,18 @@
+package com.baeldung.inputstream
+
+import java.io.InputStream
+
+fun InputStream.readUpToChar(stopChar: Char): String {
+    val stringBuilder = StringBuilder()
+    var currentChar = this.read().toChar()
+    while (currentChar != stopChar) {
+        stringBuilder.append(currentChar)
+        currentChar = this.read().toChar()
+        if (this.available() <= 0) {
+            stringBuilder.append(currentChar)
+            break
+        }
+    }
+    return stringBuilder.toString()
+}
+

core-kotlin-2/src/test/kotlin/com/baeldung/inputstream/InputStreamToStringTest.kt

@@ -0,0 +1,71 @@
+package com.baeldung.inputstream
+
+import kotlinx.io.core.use
+import org.junit.Test
+import java.io.BufferedReader
+import java.io.File
+import kotlin.test.assertEquals
+
+class InputStreamToStringTest {
+    private val fileName = "src/test/resources/inputstream2string.txt"
+    private val fileFullContent = "Computer programming can be a hassle\r\n" +
+            "It's like trying to take a defended castle"
+
+    @Test
+    fun whenReadFileWithBufferedReader_thenFullFileContentIsReadAsString() {
+        val file = File(fileName)
+        val inputStream = file.inputStream()
+        val content = inputStream.bufferedReader().use(BufferedReader::readText)
+        assertEquals(fileFullContent, content)
+    }
+    @Test
+    fun whenReadFileWithBufferedReaderReadText_thenFullFileContentIsReadAsString() {
+        val file = File(fileName)
+        val inputStream = file.inputStream()
+        val reader = BufferedReader(inputStream.reader())
+        var content: String
+        try {
+            content = reader.readText()
+        } finally {
+            reader.close()
+        }
+        assertEquals(fileFullContent, content)
+    }
+    @Test
+    fun whenReadFileWithBufferedReaderManually_thenFullFileContentIsReadAsString() {
+        val file = File(fileName)
+        val inputStream = file.inputStream()
+        val reader = BufferedReader(inputStream.reader())
+        val content = StringBuilder()
+        try {
+            var line = reader.readLine()
+            while (line != null) {
+                content.append(line)
+                line = reader.readLine()
+            }
+        } finally {
+            reader.close()
+        }
+        assertEquals(fileFullContent.replace("\r\n", ""), content.toString())
+
+    }
+
+    @Test
+    fun whenReadFileUpToStopChar_thenPartBeforeStopCharIsReadAsString() {
+        val file = File(fileName)
+        val inputStream = file.inputStream()
+        val content = inputStream.use { it.readUpToChar(' ') }
+        assertEquals("Computer", content)
+    }
+
+    @Test
+    fun whenReadFileWithoutContainingStopChar_thenFullFileContentIsReadAsString() {
+        val file = File(fileName)
+        val inputStream = file.inputStream()
+        val content = inputStream.use { it.readUpToChar('-') }
+        assertEquals(fileFullContent, content)
+    }
+
+
+}
+

core-kotlin-2/src/test/resources/inputstream2string.txt

@@ -0,0 +1,2 @@
+Computer programming can be a hassle
+It's like trying to take a defended castle