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      1 package org.junit.rules;
      2 
      3 import org.junit.runner.Description;
      4 import org.junit.runners.model.Statement;
      5 
      6 /**
      7  * Verifier is a base class for Rules like ErrorCollector, which can turn
      8  * otherwise passing test methods into failing tests if a verification check is
      9  * failed
     10  *
     11  * <pre>
     12  *     public static class ErrorLogVerifier {
     13  *        private ErrorLog errorLog = new ErrorLog();
     14  *
     15  *        &#064;Rule
     16  *        public Verifier verifier = new Verifier() {
     17  *           &#064;Override public void verify() {
     18  *              assertTrue(errorLog.isEmpty());
     19  *           }
     20  *        }
     21  *
     22  *        &#064;Test public void testThatMightWriteErrorLog() {
     23  *           // ...
     24  *        }
     25  *     }
     26  * </pre>
     27  *
     28  * @since 4.7
     29  */
     30 public abstract class Verifier implements TestRule {
     31     public Statement apply(final Statement base, Description description) {
     32         return new Statement() {
     33             @Override
     34             public void evaluate() throws Throwable {
     35                 base.evaluate();
     36                 verify();
     37             }
     38         };
     39     }
     40 
     41     /**
     42      * Override this to add verification logic. Overrides should throw an
     43      * exception to indicate that verification failed.
     44      */
     45     protected void verify() throws Throwable {
     46     }
     47 }
     48