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.extensions.sql.impl.transform.agg;
  
  import static java.math.BigDecimal.ZERO;
  import static org.apache.beam.sdk.extensions.sql.impl.transform.agg.VarianceAccumulator.newVarianceAccumulator;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotNull;
  
  import java.math.BigDecimal;
  import java.util.Arrays;
  import org.apache.beam.sdk.coders.CoderRegistry;
  import org.apache.beam.sdk.coders.VarIntCoder;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.Parameterized;
  import org.junit.runners.Parameterized.Parameters;
  
  /** Unit tests for {@link VarianceFnTest}. */
  @RunWith(Parameterized.class)
  public class VarianceFnTest {
    private static final BigDecimal FIFTEEN = new BigDecimal(15);
    private static final BigDecimal THREE = new BigDecimal(3);
    private static final BigDecimal FOUR = new BigDecimal(4);
  
    @Parameters(name = "varianceFn {index}")
    public static Iterable<Object[]> varianceFns() {
      return Arrays.asList(
          new Object[][] {
            {
              VarianceFn.newPopulation(BigDecimal::intValue),
              newVarianceAccumulator(FIFTEEN, THREE, ZERO),
              5
            },
            {
              VarianceFn.newSample(BigDecimal::intValue),
              newVarianceAccumulator(FIFTEEN, FOUR, ZERO),
              5
            }
          });
    }
  
    private VarianceFn varianceFn;
    private VarianceAccumulator testAccumulatorInput;
    private int expectedExtractedResult;
  
    public VarianceFnTest(
        VarianceFn varianceFn,
        VarianceAccumulator testAccumulatorInput,
        int expectedExtractedResult) {
  
      this.varianceFn = varianceFn;
      this.testAccumulatorInput = testAccumulatorInput;
      this.expectedExtractedResult = expectedExtractedResult;
    }
  
    @Test
    public void testCreatesEmptyAccumulator() {
      assertEquals(VarianceAccumulator.EMPTY, varianceFn.createAccumulator());
    }
  
    @Test
    public void testReturnsAccumulatorUnchangedForNullInput() {
      VarianceAccumulator accumulator = newVarianceAccumulator(ZERO, BigDecimal.ONE, BigDecimal.TEN);
  
      assertEquals(accumulator, varianceFn.addInput(accumulator, null));
    }
  
    @Test
    public void testAddsInputToAccumulator() {
      VarianceAccumulator expectedAccumulator =
          newVarianceAccumulator(ZERO, BigDecimal.ONE, new BigDecimal(2));
  
      assertEquals(
          expectedAccumulator,
          varianceFn.addInput(varianceFn.createAccumulator(), new BigDecimal(2)));
    }
  
    @Test
    public void testCreatesAccumulatorCoder() {
      assertNotNull(varianceFn.getAccumulatorCoder(CoderRegistry.createDefault(), VarIntCoder.of()));
    }
  
    @Test
    public void testExtractsOutput() {
      assertEquals(expectedExtractedResult, varianceFn.extractOutput(testAccumulatorInput));
    }
  }
  