@material-ui/core/es/styles/createTypography.spec.js

React components that implement Google's Material Design.

import { createMuiTheme } from '@material-ui/core/styles';
{
  // properties of the variants can be "unset"
  const theme = createMuiTheme({
    typography: {
      allVariants: {
        fontStyle: undefined
      }
    }
  }); // $ExpectType string | undefined

  const maybeFontStyle = theme.typography.body1.fontStyle;
}