How to use the @angular/cdk/schematics.getProjectTargetOptions function in @angular/cdk

function addThemeStyleToTarget(project: WorkspaceProject, targetName: 'test' | 'build', host: Tree,
                               assetPath: string, workspace: WorkspaceSchema) {
  // Do not update the builder options in case the target does not use the default CLI builder.
  if (!validateDefaultTargetBuilder(project, targetName)) {
    return;
  }

  const targetOptions = getProjectTargetOptions(project, targetName);

  if (!targetOptions.styles) {
    targetOptions.styles = [assetPath];
  } else {
    const existingStyles = targetOptions.styles.map(s => typeof s === 'string' ? s : s.input);

    for (let [index, stylePath] of existingStyles.entries()) {
      // If the given asset is already specified in the styles, we don't need to do anything.
      if (stylePath === assetPath) {
        return;
      }

      // In case a prebuilt theme is already set up, we can safely replace the theme with the new
      // theme file. If a custom theme is set up, we are not able to safely replace the custom
      // theme because these files can contain custom styles, while prebuilt themes are
      // always packaged and considered replaceable.

function addThemeStyleToTarget(project: WorkspaceProject, targetName: 'test' | 'build', host: Tree,
                               assetPath: string, workspace: WorkspaceSchema): void {
  // Do not update the builder options in case the target does not use the default CLI builder.
  if (!validateDefaultTargetBuilder(project, targetName)) {
    return;
  }

  const targetOptions = getProjectTargetOptions(project, targetName);

  if (!targetOptions.styles) {
    targetOptions.styles = [ assetPath ];
  } else {
    const existingStyles = targetOptions.styles.map(s => typeof s === 'string' ? s : s.input);

    for (const [ index, stylePath ] of existingStyles.entries()) {
      // If the given asset is already specified in the styles, we don't need to do anything.
      if (stylePath === assetPath) {
        return;
      }

      // In case a prebuilt theme is already set up, we can safely replace the theme with the new
      // theme file. If a custom theme is set up, we are not able to safely replace the custom
      // theme because these files can contain custom styles, while prebuilt themes are
      // always packaged and considered replaceable.

function addThemeStyleToTarget(project: WorkspaceProject, targetName: 'test' | 'build', host: Tree,
                               assetPath: string, workspace: WorkspaceSchema) {
    // Do not update the builder options in case the target does not use the default CLI builder.
    if (!validateDefaultTargetBuilder(project, targetName)) {
        return;
    }

    const targetOptions = getProjectTargetOptions(project, targetName);

    if (!targetOptions.styles) {
        targetOptions.styles = [assetPath];
    } else {
        const existingStyles = targetOptions.styles.map((s) => typeof s === 'string' ? s : s.input);

        for (const [index, stylePath] of existingStyles.entries()) {
            // If the given asset is already specified in the styles, we don't need to do anything.
            if (stylePath === assetPath) {
                return;
            }

            // In case a prebuilt theme is already set up, we can safely replace the theme with the new
            // theme file. If a custom theme is set up, we are not able to safely replace the custom
            // theme because these files can contain custom styles, while prebuilt themes are
            // always packaged and considered replaceable.

it('should not add a theme file multiple times', () => {
      writeStyleFileToWorkspace(appTree, defaultPrebuiltThemePath);

      const tree = runner.runSchematic('ng-add-setup-project', {}, appTree);
      const workspace = getWorkspace(tree);
      const project = getProjectFromWorkspace(workspace);
      const styles = getProjectTargetOptions(project, 'build').styles;

      expect(styles).toEqual(['projects/material/src/styles.css', defaultPrebuiltThemePath],
          'Expected the "styles.css" file and default prebuilt theme to be the only styles');
    });

function writeStyleFileToWorkspace(tree: Tree, stylePath: string) {
      const workspace = getWorkspace(tree);
      const project = getProjectFromWorkspace(workspace);
      const buildOptions = getProjectTargetOptions(project, 'build');

      if (!buildOptions.styles) {
        buildOptions.styles = [stylePath];
      } else {
        buildOptions.styles.push(stylePath);
      }

      tree.overwrite('/angular.json', JSON.stringify(workspace, null, 2));
    }

function expectProjectStyleFile(project: WorkspaceProject, filePath: string) {
    expect(getProjectTargetOptions(project, 'build').styles).toContain(filePath,
        `Expected "${filePath}" to be added to the project styles in the workspace.`);
  }