Only use one class name generator to avoid side effects

- Remove duplicate CSSBaseline from test app wrapper

Signed-off-by: Philipp Hugenroth <philipph@spotify.com>

packages/theme/src/unified/MuiClassNameSetup.ts

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2022 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { unstable_ClassNameGenerator as ClassNameGenerator } from '@mui/material/className';
+
+/**
+ * This API is introduced in @mui/material (v5.0.5) as a replacement of deprecated createGenerateClassName & only affects v5 MUI components from `@mui/*`
+ */
+ClassNameGenerator.configure(componentName => {
+  return `v5-${componentName}`;
+});

packages/theme/src/unified/UnifiedThemeProvider.tsx

@@ -15,31 +15,16 @@
  */
 
 import React, { ReactNode } from 'react';
-import {
-  Theme as Mui4Theme,
-  StylesProvider,
-  ThemeProvider,
-} from '@material-ui/core/styles';
+import './MuiClassNameSetup';
+import { ThemeProvider } from '@material-ui/core/styles';
 import {
   StyledEngineProvider,
-  Theme as Mui5Theme,
   ThemeProvider as Mui5Provider,
 } from '@mui/material/styles';
-import {
-  StylesProvider as Mui5StylesProvider,
-  createGenerateClassName,
-} from '@mui/styles';
 import Mui5CssBaseline from '@mui/material/CssBaseline';
 import { UnifiedTheme } from './types';
 import { CssBaseline } from '@material-ui/core';
 
-const generateV4ClassName = createGenerateClassName({
-  seed: 'm4',
-});
-const generateV5ClassName = createGenerateClassName({
-  seed: 'm5',
-});
-
 /**
  * Props for {@link UnifiedThemeProvider}.
  *
@@ -85,25 +70,14 @@ export function UnifiedThemeProvider(
   );
 
   if (v4Theme) {
-    /* const styles = maybeLoadMui4Styles();
-    if (!styles) {
-      throw new Error('Failed to load MUI 4 styles package');
-    }
-    const { StylesProvider, ThemeProvider } = styles; */
-    result = (
-      <StylesProvider generateClassName={generateV4ClassName} injectFirst>
-        <ThemeProvider theme={v4Theme as Mui4Theme}>{result}</ThemeProvider>
-      </StylesProvider>
-    );
+    result = <ThemeProvider theme={v4Theme}>{result}</ThemeProvider>;
   }
 
   if (v5Theme) {
     result = (
-      <Mui5StylesProvider generateClassName={generateV5ClassName}>
-        <StyledEngineProvider injectFirst>
-          <Mui5Provider theme={v5Theme as Mui5Theme}>{result}</Mui5Provider>
-        </StyledEngineProvider>
-      </Mui5StylesProvider>
+      <StyledEngineProvider injectFirst>
+        <Mui5Provider theme={v5Theme}>{result}</Mui5Provider>
+      </StyledEngineProvider>
     );
   }