org.hamcrest.number.BigDecimalCloseTo Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of hamcrest Show documentation

Core API and libraries of hamcrest matcher framework.

The newest version!

package org.hamcrest.number;

import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;

import java.math.BigDecimal;
import java.math.MathContext;

public class BigDecimalCloseTo extends TypeSafeMatcher {

  private final BigDecimal delta;
  private final BigDecimal value;

  public BigDecimalCloseTo(BigDecimal value, BigDecimal error) {
      this.delta = error;
      this.value = value;
  }

  @Override
  public boolean matchesSafely(BigDecimal item) {
      return actualDelta(item).compareTo(BigDecimal.ZERO) <= 0;
  }

  @Override
  public void describeMismatchSafely(BigDecimal item, Description mismatchDescription) {
      mismatchDescription.appendValue(item)
              .appendText(" differed by ")
              .appendValue(actualDelta(item))
              .appendText(" more than delta ")
              .appendValue(delta);
  }

  @Override
  public void describeTo(Description description) {
      description.appendText("a numeric value within ")
              .appendValue(delta)
              .appendText(" of ")
              .appendValue(value);
  }

  private BigDecimal actualDelta(BigDecimal item) {
      return item.subtract(value, MathContext.DECIMAL128).abs().subtract(delta, MathContext.DECIMAL128).stripTrailingZeros();
  }

  /**
   * Creates a matcher of {@link java.math.BigDecimal}s that matches when an examined BigDecimal is equal
   * to the specified operand, within a range of +/- error. The comparison for equality
   * is done by BigDecimals {@link java.math.BigDecimal#compareTo(java.math.BigDecimal)} method.
   * For example:
   * assertThat(new BigDecimal("1.03"), is(closeTo(new BigDecimal("1.0"), new BigDecimal("0.03"))))
   *
   * @param operand
   *     the expected value of matching BigDecimals
   * @param error
   *     the delta (+/-) within which matches will be allowed
   * @return The matcher.
   */
  public static Matcher closeTo(BigDecimal operand, BigDecimal error) {
      return new BigDecimalCloseTo(operand, error);
  }

}