fix: update xychart parser to correctly handle accDescr closing brace and add tests

on-behalf-of: @Mermaid-Chart <hello@mermaidchart.com>

Author: darshanr0107

.changeset/fair-swans-allow.md

@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+fix: Prevent browser hang when using multiline accDescr in XY charts

packages/mermaid/src/diagrams/xychart/parser/xychart.jison

@@ -26,7 +26,7 @@
 "accDescr"\s*":"\s*                         { this.pushState("acc_descr");return 'acc_descr'; }
 <acc_descr>(?!\n|;|#)*[^\n]*              { this.popState(); return "acc_descr_value"; }
 "accDescr"\s*"{"\s*                         { this.pushState("acc_descr_multiline");}
-<acc_descr_multiline>"{"                 { this.popState(); }
+<acc_descr_multiline>"}"                 { this.popState(); }
 <acc_descr_multiline>[^\}]*               { return "acc_descr_multiline_value"; }
 
 "xychart-beta"                            {return 'XYCHART';}

packages/mermaid/src/diagrams/xychart/parser/xychart.jison.spec.ts

@@ -19,6 +19,8 @@ const mockDB: Record<string, Mock<any>> = {
   setYAxisRangeData: vi.fn(),
   setLineData: vi.fn(),
   setBarData: vi.fn(),
+  setAccTitle: vi.fn(),
+  setAccDescription: vi.fn(),
 };
 
 function clearMocks() {
@@ -440,4 +442,43 @@ describe('Testing xychart jison file', () => {
       [45, 99, 12]
     );
   });
+
+  describe('accessibility', () => {
+    it('should handle accTitle', () => {
+      const str = 'xychart\naccTitle: Accessible Title\nx-axis [Q1, Q2]\nline [1, 2]';
+      expect(parserFnConstructor(str)).not.toThrow();
+      expect(mockDB.setAccTitle).toHaveBeenCalledWith('Accessible Title');
+    });
+
+    it('should handle single-line accDescr', () => {
+      const str = 'xychart\naccDescr: This is a description\nx-axis [Q1, Q2]\nline [1, 2]';
+      expect(parserFnConstructor(str)).not.toThrow();
+      expect(mockDB.setAccDescription).toHaveBeenCalledWith('This is a description');
+    });
+
+    it('should handle multiline accDescr', () => {
+      const str = `xychart
+accDescr {
+  This is a multiline
+  description
+}
+x-axis [Q1, Q2]
+line [1, 2]`;
+      expect(parserFnConstructor(str)).not.toThrow();
+      expect(mockDB.setAccDescription).toHaveBeenCalledWith('This is a multiline\n  description');
+    });
+
+    it('should handle both accTitle and accDescr', () => {
+      const str = `xychart
+accTitle: Sales Overview
+accDescr: Revenue report for Q1-Q4
+title "Revenue Report"
+x-axis [Q1, Q2, Q3, Q4]
+line [45, 67, 89, 55]`;
+      expect(parserFnConstructor(str)).not.toThrow();
+      expect(mockDB.setAccTitle).toHaveBeenCalledWith('Sales Overview');
+      expect(mockDB.setAccDescription).toHaveBeenCalledWith('Revenue report for Q1-Q4');
+      expect(mockDB.setDiagramTitle).toHaveBeenCalledWith('Revenue Report');
+    });
+  });
 });