const schematicRunner = new SchematicTestRunner(
      collectionName,
      pathToCollectionJson
    );
    const spy = spyOn(schematicRunner.logger, 'info');
    schematicRunner
      .callRule((host: Tree, context: SchematicContext) => {
        context.logger.info('Hello world!');
      , Tree.empty())
      .subscribe(result => {
        expect(spy).toHaveBeenCalledWith('Hello world!');
      });