TesterRequirements requirements = buildTesterRequirements(Tester.class);

    assertThat(requirements.getPresentFeatures()).isEmpty();
    assertThat(requirements.getAbsentFeatures()).isEmpty();
  }

  public void testBuildTesterRequirements_class_empty() throws Exception {
    @Require
    class Tester {}

    TesterRequirements requirements = buildTesterRequirements(Tester.class);

    TesterRequirements requirements = buildTesterRequirements(Tester.class);

    assertThat(requirements.getPresentFeatures()).isEmpty();
    assertThat(requirements.getAbsentFeatures()).isEmpty();
  }

  public void testBuildTesterRequirements_class_empty() throws Exception {
    @Require
    class Tester {}

    TesterRequirements requirements = buildTesterRequirements(Tester.class);

    synchronized (classTesterRequirementsCache) {
      TesterRequirements requirements = classTesterRequirementsCache.get(testerClass);
      if (requirements == null) {
        requirements = buildTesterRequirements(testerClass);
        classTesterRequirementsCache.put(testerClass, requirements);
      }
      return requirements;
    }
  }

  /**
   * Get the full set of requirements for a tester class.

    synchronized (classTesterRequirementsCache) {
      TesterRequirements requirements = classTesterRequirementsCache.get(testerClass);
      if (requirements == null) {
        requirements = buildTesterRequirements(testerClass);
        classTesterRequirementsCache.put(testerClass, requirements);
      }
      return requirements;
    }
  }

  /**
   * Get the full set of requirements for a tester class.