glytching / junit-extensions

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package io.github.glytching.junit.extension.benchmark;

import org.junit.jupiter.api.extension.AfterTestExecutionCallback;

import org.junit.jupiter.api.extension.BeforeTestExecutionCallback;

import org.junit.jupiter.api.extension.ExtensionContext;

import java.lang.reflect.Method;

import java.util.concurrent.TimeUnit;

import static io.github.glytching.junit.extension.util.ExtensionUtil.getStore;

/**

 * The benchmark extension publishes elapsed time to the execution listener. By default, this

 * produces output like so:

 *

 * <pre>

 * timestamp = 2018-08-30T16:28:47.701, Elapsed time in MICROSECONDS for canBenchmark = 13213

 * </pre>

 *

 * Your own implementation of the {@code EngineExecutionListener} could adopt a different template

 * for the event string or it could collect and aggregate results for all tests in a test case or it

 * could write results to somewhere other than the console etc.

 *

 * <p>By default, elapsed times are reported in {@link TimeUnit#MILLISECONDS} but you can use {@link

 * org.junit.jupiter.api.extension.RegisterExtension} to choose a different {@link TimeUnit}.

 *

 * <p>Usage example:

 *

 * <pre>

 * @ExtendWith(BenchmarkExtension.class)

 * public class MyTest {

 *

 *  @Test

 *  public void aTest() {

 *      // ...

 *  }

 * }

 * </pre>

 *

 * <pre>

 * public class MyTest {

 *

 *  // report elapsed times in a non default time unit

 *  @@RegisterExtension

 *  static BenchmarkExtension benchmarkExtension = new BenchmarkExtension(TimeUnit.MICROSECONDS);

 *

 *  @Test

 *  public void aTest() {

 *      // ...

 *  }

 * }

 * </pre>

 *

 * @since 2.4.0

 */

public class BenchmarkExtension implements BeforeTestExecutionCallback, AfterTestExecutionCallback {

  public static final String REPORT_EVENT_FORMAT = "Elapsed time in %s for %s";

  private final TimeUnit timeUnit;

  /** Constructs an instance of this class which will report using the default time unit. */

  @SuppressWarnings("unused")

  public BenchmarkExtension() {

    this(TimeUnit.MILLISECONDS);

  }

  /**

   * Constructs an instance of this class which will report using the given {@code timeUnit}.

   *

   * @param timeUnit the time unit in which benchmarks will be reported

   */

  public BenchmarkExtension(TimeUnit timeUnit) {

    this.timeUnit = timeUnit;

  }

  /**

   * Store a {@link StopWatch} instance against the test method name for use in {@link

   * #afterTestExecution(ExtensionContext)}.

   *

   * @param extensionContext the <em>context</em> in which the current test or container is being

   *     executed

   * @throws Exception

   */

  /**

   * Gather the elapsed time, using {@link StopWatch} stored by {@link

   * #beforeTestExecution(ExtensionContext)}.

   *

   * @param extensionContext the <em>context</em> in which the current test or container is being

   *     executed

   * @throws Exception

   */

  @Override

  public void afterTestExecution(ExtensionContext extensionContext) throws Exception {

    Method testMethod = extensionContext.getRequiredTestMethod();

    // get the StopWatch from the context for the current test invocation and report on it

    long duration =

        getStore(extensionContext, this.getClass())

            .get(testMethod, StopWatch.class)

            .duration(timeUnit);

    extensionContext.publishReportEntry(

        String.format(REPORT_EVENT_FORMAT, timeUnit.name(), testMethod.getName()),

        Long.toString(duration));

  }

}