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robinstrobinst
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Merge pull request #433 from stupar73/gfm-task-list-item-markdown-render
Add support for Markdown rendering for GFM task list items
2 parents 37df896 + 63b623a commit 76978a0

6 files changed

Lines changed: 158 additions & 9 deletions

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‎CHANGELOG.md‎

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## [Unreleased]
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### Added
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- Allow customizing HTML attributes for alert title `<p>` tag via `AttributeProvider`
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- Support rendering GFM task list items to Markdown
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## [0.28.0] - 2026-03-31
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### Added

‎commonmark-ext-task-list-items/src/main/java/org/commonmark/ext/task/list/items/TaskListItemsExtension.java‎

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package org.commonmark.ext.task.list.items;
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import java.util.Set;
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import org.commonmark.Extension;
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import org.commonmark.ext.task.list.items.internal.TaskListItemHtmlNodeRenderer;
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import org.commonmark.ext.task.list.items.internal.TaskListItemMarkdownNodeRenderer;
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import org.commonmark.ext.task.list.items.internal.TaskListItemPostProcessor;
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import org.commonmark.parser.Parser;
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import org.commonmark.renderer.NodeRenderer;
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import org.commonmark.renderer.html.HtmlRenderer;
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import org.commonmark.renderer.markdown.MarkdownNodeRendererContext;
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import org.commonmark.renderer.markdown.MarkdownNodeRendererFactory;
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import org.commonmark.renderer.markdown.MarkdownRenderer;
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/**
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* Extension for adding task list items.
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*
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* @since 0.15.0
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*/
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public class TaskListItemsExtension implements Parser.ParserExtension, HtmlRenderer.HtmlRendererExtension {
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public class TaskListItemsExtension implements Parser.ParserExtension, HtmlRenderer.HtmlRendererExtension,
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MarkdownRenderer.MarkdownRendererExtension {
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private TaskListItemsExtension() {
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}
@@ -34,4 +41,19 @@ public void extend(Parser.Builder parserBuilder) {
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public void extend(HtmlRenderer.Builder rendererBuilder) {
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rendererBuilder.nodeRendererFactory(TaskListItemHtmlNodeRenderer::new);
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}
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@Override
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public void extend(MarkdownRenderer.Builder rendererBuilder) {
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rendererBuilder.nodeRendererFactory(new MarkdownNodeRendererFactory() {
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@Override
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public NodeRenderer create(MarkdownNodeRendererContext context) {
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return new TaskListItemMarkdownNodeRenderer(context);
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}
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@Override
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public Set<Character> getSpecialCharacters() {
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return Set.of();
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}
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});
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}
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}

‎commonmark-ext-task-list-items/src/main/java/org/commonmark/ext/task/list/items/internal/TaskListItemHtmlNodeRenderer.java‎

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import org.commonmark.ext.task.list.items.TaskListItemMarker;
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import org.commonmark.node.Node;
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import org.commonmark.renderer.NodeRenderer;
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import org.commonmark.renderer.html.HtmlNodeRendererContext;
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import org.commonmark.renderer.html.HtmlWriter;
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import java.util.LinkedHashMap;
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import java.util.Map;
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import java.util.Set;
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public class TaskListItemHtmlNodeRenderer implements NodeRenderer {
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public class TaskListItemHtmlNodeRenderer extends TaskListItemNodeRenderer {
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private final HtmlNodeRendererContext context;
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private final HtmlWriter html;
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this.html = context.getWriter();
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}
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@Override
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public Set<Class<? extends Node>> getNodeTypes() {
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return Set.of(TaskListItemMarker.class);
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}
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@Override
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public void render(Node node) {
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if (node instanceof TaskListItemMarker) {

‎commonmark-ext-task-list-items/src/main/java/org/commonmark/ext/task/list/items/internal/TaskListItemMarkdownNodeRenderer.java‎

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package org.commonmark.ext.task.list.items.internal;
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import org.commonmark.ext.task.list.items.TaskListItemMarker;
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import org.commonmark.node.Node;
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import org.commonmark.renderer.markdown.MarkdownNodeRendererContext;
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import org.commonmark.renderer.markdown.MarkdownWriter;
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public class TaskListItemMarkdownNodeRenderer extends TaskListItemNodeRenderer {
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private final MarkdownNodeRendererContext context;
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private final MarkdownWriter writer;
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public TaskListItemMarkdownNodeRenderer(MarkdownNodeRendererContext context) {
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this.context = context;
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this.writer = context.getWriter();
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}
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@Override
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public void render(Node node) {
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if (node instanceof TaskListItemMarker) {
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var taskListItemNode = (TaskListItemMarker) node;
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var checkboxFill = taskListItemNode.isChecked() ? "x" : " ";
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writer.raw("[" + checkboxFill + "] ");
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renderChildren(node);
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}
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}
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private void renderChildren(Node parent) {
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Node node = parent.getFirstChild();
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while (node != null) {
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Node next = node.getNext();
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context.render(node);
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node = next;
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}
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}
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}

‎commonmark-ext-task-list-items/src/main/java/org/commonmark/ext/task/list/items/internal/TaskListItemNodeRenderer.java‎

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package org.commonmark.ext.task.list.items.internal;
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import java.util.Set;
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import org.commonmark.ext.task.list.items.TaskListItemMarker;
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import org.commonmark.node.Node;
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import org.commonmark.renderer.NodeRenderer;
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public abstract class TaskListItemNodeRenderer implements NodeRenderer {
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@Override
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public Set<Class<? extends Node>> getNodeTypes() {
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return Set.of(TaskListItemMarker.class);
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}
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}

‎commonmark-ext-task-list-items/src/test/java/org/commonmark/ext/task/list/items/TaskListItemMarkdownRendererTest.java‎

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package org.commonmark.ext.task.list.items;
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import java.util.Set;
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import org.commonmark.Extension;
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import org.commonmark.node.BulletList;
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import org.commonmark.node.Document;
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import org.commonmark.node.ListItem;
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import org.commonmark.node.Node;
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import org.commonmark.node.Paragraph;
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import org.commonmark.node.Text;
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import org.commonmark.parser.Parser;
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import org.commonmark.renderer.markdown.MarkdownRenderer;
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import org.junit.jupiter.api.Test;
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import static org.assertj.core.api.Assertions.assertThat;
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public class TaskListItemMarkdownRendererTest {
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private static final Set<Extension> EXTENSIONS = Set.of(TaskListItemsExtension.create());
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private static final Parser PARSER = Parser.builder().extensions(EXTENSIONS).build();
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private static final MarkdownRenderer RENDERER = MarkdownRenderer.builder().extensions(EXTENSIONS).build();
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@Test
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public void testCheckedRoundTrip() {
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assertRoundTrip("- [x] I am checked\n");
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}
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@Test
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public void testUncheckedRoundTrip() {
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assertRoundTrip("- [ ] I am unchecked\n");
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}
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@Test
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public void testMixedRoundTrip() {
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assertRoundTrip("- [x] I am checked\n- [ ] I am unchecked\n");
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}
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@Test
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public void testNestedRoundTrip() {
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assertRoundTrip("- [ ] I am unchecked\n - [x] I am a checked child\n");
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}
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@Test
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public void testFormattingRoundTrip() {
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assertRoundTrip("- [x] I am **boldly** checked\n- [ ] I am *italicly* unchecked\n");
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}
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@Test
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public void testNonTaskListItemRoundTrip() {
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assertRoundTrip("- [x] I am checked\n- [ ] I am unchecked\n- I am not a task item\n");
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}
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@Test
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public void testOrderedListRoundTrip() {
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assertRoundTrip("1. [x] I am checked\n2. [ ] I am unchecked\n");
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}
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@Test
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public void testProgrammaticallyBuilt() {
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var doc = new Document();
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var list = new BulletList();
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var item = new ListItem();
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var taskMarker = new TaskListItemMarker(false);
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var para = new Paragraph();
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var text = new Text("I am a task");
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para.appendChild(text);
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item.appendChild(taskMarker);
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item.appendChild(para);
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list.appendChild(item);
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doc.appendChild(list);
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assertRenderedEquals(doc, "- [ ] I am a task\n");
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}
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private void assertRoundTrip(String input) {
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String rendered = RENDERER.render(PARSER.parse(input));
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assertThat(rendered).isEqualTo(input);
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}
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private void assertRenderedEquals(Node inputNode, String expectedOutput) {
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var renderedOutput = RENDERER.render(inputNode);
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assertThat(renderedOutput).isEqualTo(expectedOutput);
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}
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}

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