[BAEL-3750] Breaking YAML Strings Over Multiple Lines

yaml/README.md

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+## YAML
+
+This module contains articles about YAML
+
+### Relevant articles
+
+

yaml/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>yaml</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.yaml</groupId>
+            <artifactId>snakeyaml</artifactId>
+            <version>1.21</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <snakeyaml.version>1.21</snakeyaml.version>
+    </properties>
+
+</project>

yaml/src/test/java/com/baeldung/multiline/MultiLineStringsUnitTest.java

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+package com.baeldung.multiline;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.yaml.snakeyaml.Yaml;
+
+import java.io.File;
+import java.io.InputStream;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class MultiLineStringsUnitTest {
+
+    private Yaml yaml;
+
+    @Before
+    public void setup() {
+        yaml = new Yaml();
+    }
+
+    @Test
+    public void whenLiteral_ThenLineBreaksArePresent() {
+        String key = parseYamlKey("literal.yaml");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenLiteral_ThenEndingBreaksAreReducedToOne() {
+        String key = parseYamlKey("literal2.yaml");
+        assertEquals("\n\nLine1\n\nLine2\n\nLine3\n", key);
+    }
+
+    @Test
+    public void whenFolded_ThenLineBreaksAreReplaced() {
+        String key = parseYamlKey("folded.yaml");
+        assertEquals("Line1 Line2 Line3", key);
+    }
+
+    @Test
+    public void whenFolded_ThenEmptyLinesAreReducedToOne() {
+        String key = parseYamlKey("folded2.yaml");
+        assertEquals("Line1\nLine2\n\nLine3\n", key);
+    }
+
+    @Test
+    public void whenLiteralKeep_ThenLastEmptyLinesArePresent() {
+        String key = parseYamlKey("literal_keep.yaml");
+        assertEquals("Line1\nLine2\nLine3\n\n", key);
+    }
+
+    @Test
+    public void whenLiteralStrip_ThenLastEmptyLinesAreRemoved() {
+        String key = parseYamlKey("literal_strip.yaml");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenFoldedKeep_ThenLastEmptyLinesArePresent() {
+        String key = parseYamlKey("folded_keep.yaml");
+        assertEquals("Line1 Line2 Line3\n\n\n", key);
+    }
+
+    @Test
+    public void whenFoldedStrip_ThenLastEmptyLinesAreRemoved() {
+        String key = parseYamlKey("folded_strip.yaml");
+        assertEquals("Line1 Line2 Line3", key);
+    }
+
+    @Test
+    public void whenDoubleQuotes_ThenExplicitBreaksArePreserved() {
+        String key = parseYamlKey("plain_double_quotes.yaml");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenSingleQuotes_ThenExplicitBreaksAreIgnored() {
+        String key = parseYamlKey("plain_single_quotes.yaml");
+        assertEquals("Line1\\nLine2\nLine3", key);
+    }
+
+    private String parseYamlKey(String fileName) {
+        InputStream inputStream = this.getClass()
+                .getClassLoader()
+                .getResourceAsStream("multi-line" + File.separator + fileName);
+        Map<String, String> parsed = yaml.load(inputStream);
+        return parsed.get("key");
+    }
+
+}

yaml/src/test/resources/multi-line/folded.yaml

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+key: >
+  Line1
+  Line2
+  Line3

yaml/src/test/resources/multi-line/folded2.yaml

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+key: >
+  Line1
+
+  Line2
+
+
+  Line3
+
+

yaml/src/test/resources/multi-line/folded_keep.yaml

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+key: >+
+  Line1
+  Line2
+  Line3
+
+

yaml/src/test/resources/multi-line/folded_strip.yaml

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+key: >-
+  Line1
+  Line2
+  Line3
+
+
+

yaml/src/test/resources/multi-line/literal.yaml

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+key: |
+  Line1
+  Line2
+  Line3

yaml/src/test/resources/multi-line/literal2.yaml

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+key: |
+
+
+  Line1
+
+  Line2
+
+  Line3
+
+

yaml/src/test/resources/multi-line/literal_keep.yaml

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+key: |+
+  Line1
+  Line2
+  Line3
+

yaml/src/test/resources/multi-line/literal_strip.yaml

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+key: |-
+  Line1
+  Line2
+  Line3
+

yaml/src/test/resources/multi-line/plain_double_quotes.yaml

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+key: "Line1\nLine2\nLine3"

yaml/src/test/resources/multi-line/plain_single_quotes.yaml

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+key: 'Line1\nLine2
+
+  Line3'