diff --git a/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.js b/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.js
deleted file mode 100644
index 4e9e99c70..000000000
--- a/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// eslint-disable-next-line @typescript-eslint/no-var-requires
-const fs = require('fs');
-
-import { LALRGenerator } from 'jison';
-
-describe('class diagram grammar', function () {
-  it('should introduce no new conflicts', function () {
-    const file = require.resolve('./parser/classDiagram.jison');
-    const grammarSource = fs.readFileSync(file, 'utf8');
-    const grammarParser = new LALRGenerator(grammarSource, {});
-    expect(grammarParser.conflicts < 16).toBe(true);
-  });
-});
diff --git a/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts b/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts
new file mode 100644
index 000000000..eb0c37969
--- /dev/null
+++ b/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts
@@ -0,0 +1,16 @@
+import { readFile } from 'node:fs/promises';
+// @ts-ignore - no types
+import { LALRGenerator } from 'jison';
+import path from 'path';
+
+const getAbsolutePath = (relativePath: string) => {
+  return new URL(path.join(path.dirname(import.meta.url), relativePath)).pathname;
+};
+
+describe('class diagram grammar', function () {
+  it('should have no conflicts', async function () {
+    const grammarSource = await readFile(getAbsolutePath('./parser/classDiagram.jison'), 'utf8');
+    const grammarParser = new LALRGenerator(grammarSource, {});
+    expect(grammarParser.conflicts).toBe(0);
+  });
+});