package org.junit.runner;
   
   import org.junit.runners.Suite;
   import org.junit.runners.model.InitializationError;
   import org.junit.runners.model.RunnerBuilder;
   
   /**
    * Represents a strategy for computing runners and suites.
    * WARNING: this class is very likely to undergo serious changes in version 4.8 and
   * beyond.
   *
   * @since 4.6
   */
  public class Computer {
      /**
       * Returns a new default computer, which runs tests in serial order
       */
      public static Computer serial() {
          return new Computer();
      }
  
      /**
       * Create a suite for {@code classes}, building Runners with {@code builder}.
       * Throws an InitializationError if Runner construction fails
       */
      public Runner getSuite(final RunnerBuilder builder,
              Class<?>[] classes) throws InitializationError {
          return new Suite(new RunnerBuilder() {
              @Override
              public Runner runnerForClass(Class<?> testClass) throws Throwable {
                  return getRunner(builder, testClass);
              }
          }, classes);
      }
  
      /**
       * Create a single-class runner for {@code testClass}, using {@code builder}
       */
      protected Runner getRunner(RunnerBuilder builder, Class<?> testClass) throws Throwable {
          return builder.runnerForClass(testClass);
      }
  }