content: /*
   * 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 org.apache.beam.sdk.testutils.metrics;
  
  import static org.junit.Assert.assertEquals;
  
  import java.util.Arrays;
  import java.util.List;
  import org.apache.beam.sdk.PipelineResult;
  import org.apache.beam.sdk.metrics.Counter;
  import org.apache.beam.sdk.metrics.Distribution;
  import org.apache.beam.sdk.metrics.Metrics;
  import org.apache.beam.sdk.testing.TestPipeline;
  import org.apache.beam.sdk.transforms.Create;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.MapElements;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.SimpleFunction;
  import org.apache.beam.sdk.values.PCollection;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.JUnit4;
  
  /** Tests for {@link MetricsReader}. */
  @RunWith(JUnit4.class)
  public class MetricsReaderTest {
  
    @Rule public TestPipeline testPipeline = TestPipeline.create();
  
    private static final String NAMESPACE = "Testing";
  
    @Test
    public void testCounterMetricReceivedFromPipelineResult() {
      List<Integer> sampleInputData = Arrays.asList(1, 1, 1, 1, 1);
  
      createTestPipeline(sampleInputData, new MonitorWithCounter());
      PipelineResult result = testPipeline.run();
  
      MetricsReader reader = new MetricsReader(result, NAMESPACE);
  
      assertEquals(5, reader.getCounterMetric("counter"));
    }
  
    @Test
    public void testStartTimeIsTheMinimumFromAllCollectedDistributions() {
      List<Integer> sampleInputData = Arrays.asList(1, 2, 3, 4, 5);
  
      createTestPipelineWithBranches(sampleInputData);
  
      PipelineResult result = testPipeline.run();
      MetricsReader reader = new MetricsReader(result, NAMESPACE, 0);
      assertEquals(1, reader.getStartTimeMetric("timeDist"));
    }
  
    @Test
    public void testEndTimeIsTheMaximumOfAllCollectedDistributions() {
      List<Integer> sampleInputData = Arrays.asList(1, 2, 3, 4, 5);
  
      createTestPipelineWithBranches(sampleInputData);
  
      PipelineResult result = testPipeline.run();
      MetricsReader reader = new MetricsReader(result, NAMESPACE, 0);
      assertEquals(10, reader.getEndTimeMetric("timeDist"));
    }
  
    /**
     * Branching pipelines ensure that multiple metric results of the same name are created. Thanks to
     * that it is possible to test if MetricsReader can collect metrics in such case.
     */
    private void createTestPipelineWithBranches(List<Integer> sampleInputData) {
      PCollection<Integer> inputData = testPipeline.apply(Create.of(sampleInputData));
      inputData.apply("Monitor #1", ParDo.of(new MonitorWithTimeDistribution()));
  
      inputData
          .apply("Multiply input", MapElements.via(new MultiplyElements()))
          .apply("Monitor #2", ParDo.of(new MonitorWithTimeDistribution()));
    }
  
    @Test
    public void doesntThrowIllegalStateExceptionWhenThereIsNoMetricFound() {
      PipelineResult result = testPipeline.run();
      MetricsReader reader = new MetricsReader(result, NAMESPACE);
      reader.getCounterMetric("nonexistent");
    }
  
    @Test
    public void testTimeIsMinusOneIfTimeMetricIsTooFarFromNow() {
      List<Integer> sampleInputData = Arrays.asList(1, 5, 5, 5, 5);
  
      createTestPipeline(sampleInputData, new MonitorWithTimeDistribution());
      PipelineResult result = testPipeline.run();
  
      MetricsReader reader = new MetricsReader(result, NAMESPACE, 900000000001L);
  
      assertEquals(-1, reader.getStartTimeMetric("timeDist"));
      assertEquals(-1, reader.getEndTimeMetric("timeDist"));
    }
  
    private void createTestPipeline(List<Integer> sampleInputData, DoFn<Integer, Integer> monitor) {
      testPipeline.apply(Create.of(sampleInputData)).apply(ParDo.of(monitor));
    }
  
    /** Counts total elements of the input data provided. */
    private static class MonitorWithCounter extends DoFn<Integer, Integer> {
      private final Counter elementCounter = Metrics.counter(NAMESPACE, "counter");
  
      @ProcessElement
      public void processElement(ProcessContext c) {
        elementCounter.inc();
      }
    }
  
    /** Simulates time flow by updating the distribution metric with input collection elements. */
    private static class MonitorWithTimeDistribution extends DoFn<Integer, Integer> {
      private final Distribution timeDistribution = Metrics.distribution(NAMESPACE, "timeDist");
  
      @ProcessElement
      public void processElement(ProcessContext c) {
        timeDistribution.update(c.element().longValue());
      }
    }
  
    private static class MultiplyElements extends SimpleFunction<Integer, Integer> {
      @Override
      public Integer apply(Integer input) {
        return input * 2;
      }
    }
  }
  