Add isWithin().of() support to LongSubject.

RELNOTES=Added `isWithin().of()` support to `LongSubject`.
PiperOrigin-RevId: 586097910

core/src/main/java/com/google/common/truth/LongSubject.java

@@ -15,6 +15,11 @@
  */
 package com.google.common.truth;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.truth.MathUtil.equalWithinTolerance;
+import static com.google.common.truth.Fact.fact;
+
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -25,12 +30,111 @@
  * @author Kurt Alfred Kluever
  */
 public class LongSubject extends ComparableSubject<Long> {
+
+  private final @Nullable Long actual;
+
   /**
    * Constructor for use by subclasses. If you want to create an instance of this class itself, call
    * {@link Subject#check(String, Object...) check(...)}{@code .that(actual)}.
    */
   protected LongSubject(FailureMetadata metadata, @Nullable Long actual) {
     super(metadata, actual);
+    this.actual = actual;
+  }
+
+  /**
+   * A partially specified check about an approximate relationship to a {@code long} subject using a
+   * tolerance.
+   *
+   * @since 1.2
+   */
+  public abstract static class TolerantLongComparison {
+
+    // Prevent subclassing outside of this class
+    private TolerantLongComparison() {}
+
+    /**
+     * Fails if the subject was expected to be within the tolerance of the given value but was not
+     * <i>or</i> if it was expected <i>not</i> to be within the tolerance but was. The subject and
+     * tolerance are specified earlier in the fluent call chain.
+     */
+    public abstract void of(long expectedLong);
+
+    /**
+     * @throws UnsupportedOperationException always
+     * @deprecated {@link Object#equals(Object)} is not supported on TolerantLongComparison. If you
+     *     meant to compare longs, use {@link #of(long)} instead.
+     */
+    @Deprecated
+    @Override
+    public boolean equals(@Nullable Object o) {
+      throw new UnsupportedOperationException(
+          "If you meant to compare longs, use .of(long) instead.");
+    }
+
+    /**
+     * @throws UnsupportedOperationException always
+     * @deprecated {@link Object#hashCode()} is not supported on TolerantLongComparison
+     */
+    @Deprecated
+    @Override
+    public int hashCode() {
+      throw new UnsupportedOperationException("Subject.hashCode() is not supported.");
+    }
+  }
+
+  /**
+   * Prepares for a check that the subject is a number within the given tolerance of an expected
+   * value that will be provided in the next call in the fluent chain.
+   *
+   * @param tolerance an inclusive upper bound on the difference between the subject and object
+   *     allowed by the check, which must be a non-negative value.
+   * @since 1.2
+   */
+  public TolerantLongComparison isWithin(long tolerance) {
+    return new TolerantLongComparison() {
+      @Override
+      public void of(long expected) {
+        Long actual = LongSubject.this.actual;
+        checkNotNull(
+            actual, "actual value cannot be null. tolerance=%s expected=%s", tolerance, expected);
+        checkTolerance(tolerance);
+
+        if (!equalWithinTolerance(actual, expected, tolerance)) {
+          failWithoutActual(
+              fact("expected", Long.toString(expected)),
+              butWas(),
+              fact("outside tolerance", Long.toString(tolerance)));
+        }
+      }
+    };
+  }
+
+  /**
+   * Prepares for a check that the subject is a number not within the given tolerance of an expected
+   * value that will be provided in the next call in the fluent chain.
+   *
+   * @param tolerance an exclusive lower bound on the difference between the subject and object
+   *     allowed by the check, which must be a non-negative value.
+   * @since 1.2
+   */
+  public TolerantLongComparison isNotWithin(long tolerance) {
+    return new TolerantLongComparison() {
+      @Override
+      public void of(long expected) {
+        Long actual = LongSubject.this.actual;
+        checkNotNull(
+            actual, "actual value cannot be null. tolerance=%s expected=%s", tolerance, expected);
+        checkTolerance(tolerance);
+
+        if (equalWithinTolerance(actual, expected, tolerance)) {
+          failWithoutActual(
+              fact("expected not to be", Long.toString(expected)),
+              butWas(),
+              fact("within tolerance", Long.toString(tolerance)));
+        }
+      }
+    };
   }
 
   /**
@@ -42,6 +146,11 @@ public final void isEquivalentAccordingToCompareTo(@Nullable Long other) {
     super.isEquivalentAccordingToCompareTo(other);
   }
 
+  /** Ensures that the given tolerance is a non-negative value. */
+  static void checkTolerance(long tolerance) {
+    checkArgument(tolerance >= 0, "tolerance (%s) cannot be negative", tolerance);
+  }
+
   /**
    * Checks that the subject is greater than {@code other}.
    *

core/src/main/java/com/google/common/truth/MathUtil.java

@@ -16,12 +16,30 @@
 
 package com.google.common.truth;
 
+import static java.lang.Math.subtractExact;
+
 import com.google.common.primitives.Doubles;
 
 /** Math utilities to be shared by numeric subjects. */
 final class MathUtil {
   private MathUtil() {}
 
+  /**
+   * Returns true iff {@code left} and {@code right} are values within {@code tolerance} of each
+   * other.
+   */
+  /* package */ static boolean equalWithinTolerance(long left, long right, long tolerance) {
+    try {
+      // subtractExact is always desugared.
+      @SuppressWarnings({"AndroidJdkLibsChecker", "Java7ApiChecker"})
+      long absDiff = Math.abs(subtractExact(left, right));
+      return 0 <= absDiff && absDiff <= Math.abs(tolerance);
+    } catch (ArithmeticException e) {
+      // The numbers are so far apart their difference isn't even a long.
+      return false;
+    }
+  }
+
   /**
    * Returns true iff {@code left} and {@code right} are finite values within {@code tolerance} of
    * each other. Note that both this method and {@link #notEqualWithinTolerance} returns false if

core/src/test/java/com/google/common/truth/LongSubjectTest.java

@@ -15,8 +15,12 @@
  */
 package com.google.common.truth;
 
+import static com.google.common.truth.ExpectFailure.assertThat;
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.fail;
 
+import com.google.common.truth.ExpectFailure.SimpleSubjectBuilderCallback;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -129,6 +133,140 @@ public void isAtMost_int() {
     assertThat(2L).isAtMost(3);
   }
 
+  @Test
+  public void isWithinOf() {
+    assertThat(20000L).isWithin(0L).of(20000L);
+    assertThat(20000L).isWithin(1L).of(20000L);
+    assertThat(20000L).isWithin(10000L).of(20000L);
+    assertThat(20000L).isWithin(10000L).of(30000L);
+    assertThat(Long.MIN_VALUE).isWithin(1L).of(Long.MIN_VALUE + 1);
+    assertThat(Long.MAX_VALUE).isWithin(1L).of(Long.MAX_VALUE - 1);
+    assertThat(Long.MAX_VALUE / 2).isWithin(Long.MAX_VALUE).of(-Long.MAX_VALUE / 2);
+    assertThat(-Long.MAX_VALUE / 2).isWithin(Long.MAX_VALUE).of(Long.MAX_VALUE / 2);
+
+    assertThatIsWithinFails(20000L, 9999L, 30000L);
+    assertThatIsWithinFails(20000L, 10000L, 30001L);
+    assertThatIsWithinFails(Long.MIN_VALUE, 0L, Long.MAX_VALUE);
+    assertThatIsWithinFails(Long.MAX_VALUE, 0L, Long.MIN_VALUE);
+    assertThatIsWithinFails(Long.MIN_VALUE, 1L, Long.MIN_VALUE + 2);
+    assertThatIsWithinFails(Long.MAX_VALUE, 1L, Long.MAX_VALUE - 2);
+    // Don't fall for rollover
+    assertThatIsWithinFails(Long.MIN_VALUE, 1L, Long.MAX_VALUE);
+    assertThatIsWithinFails(Long.MAX_VALUE, 1L, Long.MIN_VALUE);
+  }
+
+  private static void assertThatIsWithinFails(long actual, long tolerance, long expected) {
+    ExpectFailure.SimpleSubjectBuilderCallback<LongSubject, Long> callback =
+        new ExpectFailure.SimpleSubjectBuilderCallback<LongSubject, Long>() {
+          @Override
+          public void invokeAssertion(SimpleSubjectBuilder<LongSubject, Long> expect) {
+            expect.that(actual).isWithin(tolerance).of(expected);
+          }
+        };
+    AssertionError failure = expectFailure(callback);
+    assertThat(failure)
+        .factKeys()
+        .containsExactly("expected", "but was", "outside tolerance")
+        .inOrder();
+    assertThat(failure).factValue("expected").isEqualTo(Long.toString(expected));
+    assertThat(failure).factValue("but was").isEqualTo(Long.toString(actual));
+    assertThat(failure).factValue("outside tolerance").isEqualTo(Long.toString(tolerance));
+  }
+
+  @Test
+  public void isNotWithinOf() {
+    assertThatIsNotWithinFails(20000L, 0L, 20000L);
+    assertThatIsNotWithinFails(20000L, 1L, 20000L);
+    assertThatIsNotWithinFails(20000L, 10000L, 20000L);
+    assertThatIsNotWithinFails(20000L, 10000L, 30000L);
+    assertThatIsNotWithinFails(Long.MIN_VALUE, 1L, Long.MIN_VALUE + 1);
+    assertThatIsNotWithinFails(Long.MAX_VALUE, 1L, Long.MAX_VALUE - 1);
+    assertThatIsNotWithinFails(Long.MAX_VALUE / 2, Long.MAX_VALUE, -Long.MAX_VALUE / 2);
+    assertThatIsNotWithinFails(-Long.MAX_VALUE / 2, Long.MAX_VALUE, Long.MAX_VALUE / 2);
+
+    assertThat(20000L).isNotWithin(9999L).of(30000L);
+    assertThat(20000L).isNotWithin(10000L).of(30001L);
+    assertThat(Long.MIN_VALUE).isNotWithin(0L).of(Long.MAX_VALUE);
+    assertThat(Long.MAX_VALUE).isNotWithin(0L).of(Long.MIN_VALUE);
+    assertThat(Long.MIN_VALUE).isNotWithin(1L).of(Long.MIN_VALUE + 2);
+    assertThat(Long.MAX_VALUE).isNotWithin(1L).of(Long.MAX_VALUE - 2);
+    // Don't fall for rollover
+    assertThat(Long.MIN_VALUE).isNotWithin(1L).of(Long.MAX_VALUE);
+    assertThat(Long.MAX_VALUE).isNotWithin(1L).of(Long.MIN_VALUE);
+  }
+
+  private static void assertThatIsNotWithinFails(long actual, long tolerance, long expected) {
+    ExpectFailure.SimpleSubjectBuilderCallback<LongSubject, Long> callback =
+        new ExpectFailure.SimpleSubjectBuilderCallback<LongSubject, Long>() {
+          @Override
+          public void invokeAssertion(SimpleSubjectBuilder<LongSubject, Long> expect) {
+            expect.that(actual).isNotWithin(tolerance).of(expected);
+          }
+        };
+    AssertionError failure = expectFailure(callback);
+    assertThat(failure).factValue("expected not to be").isEqualTo(Long.toString(expected));
+    assertThat(failure).factValue("within tolerance").isEqualTo(Long.toString(tolerance));
+  }
+
+  @Test
+  public void isWithinIntegers() {
+    assertThat(20000L).isWithin(0).of(20000);
+    assertThat(20000L).isWithin(1).of(20000);
+    assertThat(20000L).isWithin(10000).of(20000);
+    assertThat(20000L).isWithin(10000).of(30000);
+
+    assertThat(20000L).isNotWithin(0).of(200000);
+    assertThat(20000L).isNotWithin(1).of(200000);
+    assertThat(20000L).isNotWithin(10000).of(200000);
+    assertThat(20000L).isNotWithin(10000).of(300000);
+  }
+
+  @Test
+  public void isWithinNegativeTolerance() {
+    isWithinNegativeToleranceThrowsIAE(0L, -10, 5);
+    isWithinNegativeToleranceThrowsIAE(0L, -10, 20);
+    isNotWithinNegativeToleranceThrowsIAE(0L, -10, 5);
+    isNotWithinNegativeToleranceThrowsIAE(0L, -10, 20);
+  }
+
+  private static void isWithinNegativeToleranceThrowsIAE(
+      long actual, long tolerance, long expected) {
+    try {
+      assertThat(actual).isWithin(tolerance).of(expected);
+      fail("Expected IllegalArgumentException to be thrown but wasn't");
+    } catch (IllegalArgumentException iae) {
+      assertThat(iae)
+          .hasMessageThat()
+          .isEqualTo("tolerance (" + tolerance + ") cannot be negative");
+    }
+  }
+
+  private static void isNotWithinNegativeToleranceThrowsIAE(
+      long actual, long tolerance, long expected) {
+    try {
+      assertThat(actual).isNotWithin(tolerance).of(expected);
+      fail("Expected IllegalArgumentException to be thrown but wasn't");
+    } catch (IllegalArgumentException iae) {
+      assertThat(iae)
+          .hasMessageThat()
+          .isEqualTo("tolerance (" + tolerance + ") cannot be negative");
+    }
+  }
+
+  private static final Subject.Factory<LongSubject, Long> LONG_SUBJECT_FACTORY =
+      new Subject.Factory<LongSubject, Long>() {
+        @Override
+        public LongSubject createSubject(FailureMetadata metadata, Long that) {
+          return new LongSubject(metadata, that);
+        }
+      };
+
+  @CanIgnoreReturnValue
+  private static AssertionError expectFailure(
+      SimpleSubjectBuilderCallback<LongSubject, Long> callback) {
+    return ExpectFailure.expectFailureAbout(LONG_SUBJECT_FACTORY, callback);
+  }
+
   private LongSubject expectFailureWhenTestingThat(Long actual) {
     return expectFailure.whenTesting().that(actual);
   }