[material-ui] Skip generating modularCssLayers CSS var (#46329)

Author: siriwatknp

packages/mui-material/src/styles/extendTheme.test.js

@@ -865,4 +865,11 @@ describe('extendTheme', () => {
       ]);
     });
   });
+
+  it('should not generate vars for modularCssLayers', () => {
+    const theme = extendTheme({
+      modularCssLayers: '@layer mui,utilities;',
+    });
+    expect(theme.vars.modularCssLayers).to.equal(undefined);
+  });
 });

packages/mui-material/src/styles/shouldSkipGeneratingVar.ts

@@ -1,7 +1,7 @@
 export default function shouldSkipGeneratingVar(keys: string[]) {
   return (
     !!keys[0].match(
-      /(cssVarPrefix|colorSchemeSelector|rootSelector|typography|mixins|breakpoints|direction|transitions)/,
+      /(cssVarPrefix|colorSchemeSelector|modularCssLayers|rootSelector|typography|mixins|breakpoints|direction|transitions)/,
     ) ||
     !!keys[0].match(/sxConfig$/) || // ends with sxConfig
     (keys[0] === 'palette' && !!keys[1]?.match(/(mode|contrastThreshold|tonalOffset)/))