Create Core Kotlin IO module

core-kotlin-io/.gitignore

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+/bin/
+
+#ignore gradle
+.gradle/
+
+
+#ignore build and generated files
+build/
+node/
+target/
+out/

core-kotlin-io/README.md

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+## Relevant articles:
+
+- [InputStream to String in Kotlin](https://www.baeldung.com/kotlin-inputstream-to-string)

core-kotlin-io/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin-io</artifactId>
+    <name>core-kotlin-io</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-kotlin</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../parent-kotlin</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit.platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test</artifactId>
+            <version>${kotlin.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <version>${kotlin.version}</version>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>test-compile</id>
+                        <phase>test-compile</phase>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <jvmTarget>1.8</jvmTarget>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <kotlin.version>1.2.71</kotlin.version>
+        <junit.platform.version>1.1.1</junit.platform.version>
+        <junit.vintage.version>5.2.0</junit.vintage.version>
+        <assertj.version>3.10.0</assertj.version>
+    </properties>
+
+</project>

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

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+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-io/src/test/kotlin/com/baeldung/inputstream/InputStreamToStringTest.kt

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+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-io/src/test/resources/inputstream2string.txt

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+Computer programming can be a hassle
+It's like trying to take a defended castle