fix(EuiCode): fix code block copy button not including the last character

src/components/code/code_block_copy.spec.tsx

@@ -105,8 +105,6 @@ describe('EuiCodeBlock copy UX', () => {
     cy.realMount(<EuiCodeBlock isCopyable>{questionContent}</EuiCodeBlock>);
 
     cy.get('[data-test-subj="euiCodeBlockCopy"]').realClick();
-    // TODO: Remove incorrect assertion and uncomment correct assertion once bug is fixed
-    assertClipboardContentEquals('hello\n\nworld');
-    // assertClipboardContentEquals(questionContent);
+    assertClipboardContentEquals(questionContent);
   });
 });

src/components/code/code_block_copy.tsx

@@ -11,6 +11,7 @@ import { useInnerText } from '../inner_text';
 import { EuiCopy } from '../copy';
 import { useEuiI18n } from '../i18n';
 import { EuiButtonIcon } from '../button';
+import { NEW_LINE_REGEX_GLOBAL } from './utils';
 
 /**
  * Hook that returns copy-related state/logic/utils
@@ -26,7 +27,14 @@ export const useCopy = ({
 }) => {
   const [innerTextRef, _innerText] = useInnerText('');
   const innerText = useMemo(
-    () => _innerText?.replace(/[\r\n?]{2}|\n\n/g, '\n') || '',
+    () =>
+      _innerText
+        // Normalize line terminations to match native JS format
+        ?.replace(NEW_LINE_REGEX_GLOBAL, '\n')
+        // Reduce two or more consecutive new line characters to a single one
+        // This is needed primarily because of how syntax highlighting
+        // generated DOM elements affect `innerText` output.
+        .replace(/\n{2,}/g, '\n') || '',
     [_innerText]
   );
   const textToCopy = isVirtualized ? `${children}` : innerText; // Virtualized code blocks do not have inner text

src/components/code/utils.tsx

@@ -41,6 +41,22 @@ export type EuiCodeSharedProps = CommonProps &
 export const SUPPORTED_LANGUAGES = listLanguages();
 export const DEFAULT_LANGUAGE = 'text';
 
+/**
+ * Platform-agnostic new line regex that safely matches all standard
+ * line termination conventions:
+ * - LF: Unix-based platforms and JS-native sources like text areas
+ * - CRLF: Windows
+ * - CR: Mac Classic; to support files saved a long time ago
+ */
+export const NEW_LINE_REGEX = /\r\n|\r|\n/;
+
+/**
+ * Platform-agnostic global new line regex that safely matches all standard
+ * line termination conventions.
+ * See [NEW_LINE_REGEX]{@link NEW_LINE_REGEX} for more details.
+ */
+export const NEW_LINE_REGEX_GLOBAL = new RegExp(NEW_LINE_REGEX, 'g');
+
 export const checkSupportedLanguage = (language: string): string => {
   return SUPPORTED_LANGUAGES.includes(language) ? language : DEFAULT_LANGUAGE;
 };
@@ -143,12 +159,12 @@ const addLineData = (
   return nodes.reduce<ExtendedRefractorNode[]>((result, node) => {
     const lineStart = data.lineNumber;
     if (node.type === 'text') {
-      if (!node.value.match(/\r\n?|\n/)) {
+      if (!node.value.match(NEW_LINE_REGEX)) {
         node.lineStart = lineStart;
         node.lineEnd = lineStart;
         result.push(node);
       } else {
-        const lines = node.value.split(/\r\n?|\n/);
+        const lines = node.value.split(NEW_LINE_REGEX);
         lines.forEach((line, i) => {
           const num = i === 0 ? data.lineNumber : ++data.lineNumber;
           result.push({

upcoming_changelogs/6794.md

@@ -0,0 +1,3 @@
+**Bug fixes**
+
+- Fixed `EuiCodeBlock` potentially incorrectly ignoring lines ending with a question mark when using the Copy button.