Make RectangularRadioButton.options.accessibleName default based on a…

… tandem name, if it is supplied, see phetsims/buoyancy#109

js/Tandem.ts

@@ -11,9 +11,10 @@
 import arrayRemove from '../../phet-core/js/arrayRemove.js';
 import merge from '../../phet-core/js/merge.js';
 import optionize from '../../phet-core/js/optionize.js';
-import PhetioObject from './PhetioObject.js';
+import PhetioObject, { PhetioObjectOptions } from './PhetioObject.js';
 import TandemConstants, { PhetioID } from './TandemConstants.js';
 import tandemNamespace from './tandemNamespace.js';
+import PickOptional from '../../phet-core/js/types/PickOptional.js';
 
 // constants
 // Tandem can't depend on joist, so cannot use packageJSON module
@@ -597,6 +598,32 @@ class Tandem {
    * Use this as the parent tandem for Properties that are related to sim-specific preferences.
    */
   public static readonly PREFERENCES = Tandem.GLOBAL_MODEL.createTandem( 'preferences' );
+
+  /**
+   * Convenience method to get an accessibleName from providedOptions, see tandemNameToAccessibleName
+   */
+  public static toAccessibleName( providedOptions: PickOptional<PhetioObjectOptions, 'tandem'> | undefined, suffix: string ): string | null {
+    if ( providedOptions && providedOptions.tandem && providedOptions.tandem.supplied ) {
+      return Tandem.tandemNameToAccessibleName( providedOptions.tandem.name, suffix );
+    }
+    return null;
+  }
+
+  /**
+   * Tandem names can be used to create accessible names for screen readers. This method will convert a tandem name to
+   * a human-readable name. For example, 'resetAllButton' would become 'Reset All'.
+   */
+  public static tandemNameToAccessibleName( tandemName: string, suffix: string ): string | null {
+    assert && assert( tandemName.toLowerCase().endsWith( suffix.toLowerCase() ), `suffix should be at the end of the tandem name: ${tandemName}` );
+
+    // trim the suffix
+    const withoutSuffix = tandemName.slice( 0, -suffix.length );
+
+    const whitespaceName = withoutSuffix.replace( /([A-Z])/g, ' $1' ).trim();
+
+    // capitalize the first letter of each word, no matter how many words
+    return whitespaceName.replace( /\b\w/g, c => c.toUpperCase() );
+  }
 }
 
 Tandem.addLaunchListener( () => {