/*
 * 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.runners.direct;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.containsInAnyOrder;
import static org.hamcrest.Matchers.emptyIterable;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.nullValue;
import static org.hamcrest.Matchers.theInstance;
import static org.junit.Assert.assertNull;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;

import org.apache.beam.runners.core.StateNamespace;
import org.apache.beam.runners.core.StateNamespaceForTest;
import org.apache.beam.runners.core.StateNamespaces;
import org.apache.beam.runners.core.StateTag;
import org.apache.beam.runners.core.StateTags;
import org.apache.beam.sdk.coders.CannotProvideCoderException;
import org.apache.beam.sdk.coders.CoderRegistry;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.coders.VarIntCoder;
import org.apache.beam.sdk.state.BagState;
import org.apache.beam.sdk.state.CombiningState;
import org.apache.beam.sdk.state.GroupingState;
import org.apache.beam.sdk.state.MapState;
import org.apache.beam.sdk.state.SetState;
import org.apache.beam.sdk.state.ValueState;
import org.apache.beam.sdk.state.WatermarkHoldState;
import org.apache.beam.sdk.testing.TestPipeline;
import org.apache.beam.sdk.transforms.Combine.CombineFn;
import org.apache.beam.sdk.transforms.Sum;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.transforms.windowing.TimestampCombiner;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.Lists;
import org.joda.time.Instant;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link CopyOnAccessInMemoryStateInternals}. */
@RunWith(JUnit4.class)
public class CopyOnAccessInMemoryStateInternalsTest {

  @Rule public final TestPipeline pipeline = TestPipeline.create();
  @Rule public ExpectedException thrown = ExpectedException.none();
  private String key = "foo";

  @Test
  public void testGetWithEmpty() {
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = internals.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");
    assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));

    BagState<String> reReadStringBag = internals.state(namespace, bagTag);
    assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));
  }

  @Test
  public void testGetWithAbsentInUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = internals.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");
    assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));

    BagState<String> reReadVoidBag = internals.state(namespace, bagTag);
    assertThat(reReadVoidBag.read(), containsInAnyOrder("baz", "bar"));

    BagState<String> underlyingState = underlying.state(namespace, bagTag);
    assertThat(underlyingState.read(), emptyIterable());
  }

  /**
   * Tests that retrieving state with an underlying StateInternals with an existing value returns a
   * value that initially has equal value to the provided state but can be modified without
   * modifying the existing state.
   */
  @Test
  public void testGetWithPresentInUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<ValueState<String>> valueTag = StateTags.value("foo", StringUtf8Coder.of());
    ValueState<String> underlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.read(), nullValue(String.class));

    underlyingValue.write("bar");
    assertThat(underlyingValue.read(), equalTo("bar"));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    ValueState<String> copyOnAccessState = internals.state(namespace, valueTag);
    assertThat(copyOnAccessState.read(), equalTo("bar"));

    copyOnAccessState.write("baz");
    assertThat(copyOnAccessState.read(), equalTo("baz"));
    assertThat(underlyingValue.read(), equalTo("bar"));

    ValueState<String> reReadUnderlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
  }

  @Test
  public void testBagStateWithUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<Integer>> valueTag = StateTags.bag("foo", VarIntCoder.of());
    BagState<Integer> underlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.read(), emptyIterable());

    underlyingValue.add(1);
    assertThat(underlyingValue.read(), containsInAnyOrder(1));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    BagState<Integer> copyOnAccessState = internals.state(namespace, valueTag);
    assertThat(copyOnAccessState.read(), containsInAnyOrder(1));

    copyOnAccessState.add(4);
    assertThat(copyOnAccessState.read(), containsInAnyOrder(4, 1));
    assertThat(underlyingValue.read(), containsInAnyOrder(1));

    BagState<Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
    assertThat(
        Lists.newArrayList(underlyingValue.read()),
        equalTo(Lists.newArrayList(reReadUnderlyingValue.read())));
  }

  @Test
  public void testSetStateWithUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<SetState<Integer>> valueTag = StateTags.set("foo", VarIntCoder.of());
    SetState<Integer> underlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.read(), emptyIterable());

    underlyingValue.add(1);
    assertThat(underlyingValue.read(), containsInAnyOrder(1));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    SetState<Integer> copyOnAccessState = internals.state(namespace, valueTag);
    assertThat(copyOnAccessState.read(), containsInAnyOrder(1));

    copyOnAccessState.add(4);
    assertThat(copyOnAccessState.read(), containsInAnyOrder(4, 1));
    assertThat(underlyingValue.read(), containsInAnyOrder(1));

    SetState<Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
  }

  @Test
  public void testMapStateWithUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<MapState<String, Integer>> valueTag =
        StateTags.map("foo", StringUtf8Coder.of(), VarIntCoder.of());
    MapState<String, Integer> underlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.entries().read(), emptyIterable());

    underlyingValue.put("hello", 1);
    assertThat(underlyingValue.get("hello").read(), equalTo(1));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    MapState<String, Integer> copyOnAccessState = internals.state(namespace, valueTag);
    assertThat(copyOnAccessState.get("hello").read(), equalTo(1));

    copyOnAccessState.put("world", 4);
    assertThat(copyOnAccessState.get("hello").read(), equalTo(1));
    assertThat(copyOnAccessState.get("world").read(), equalTo(4));
    assertThat(underlyingValue.get("hello").read(), equalTo(1));
    assertNull(underlyingValue.get("world").read());

    MapState<String, Integer> reReadUnderlyingValue = underlying.state(namespace, valueTag);
    assertThat(underlyingValue.entries().read(), equalTo(reReadUnderlyingValue.entries().read()));
  }

  @Test
  public void testAccumulatorCombiningStateWithUnderlying() throws CannotProvideCoderException {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CombineFn<Long, long[], Long> sumLongFn = Sum.ofLongs();

    StateNamespace namespace = new StateNamespaceForTest("foo");
    CoderRegistry reg = pipeline.getCoderRegistry();
    StateTag<CombiningState<Long, long[], Long>> stateTag =
        StateTags.combiningValue(
            "summer", sumLongFn.getAccumulatorCoder(reg, reg.getCoder(Long.class)), sumLongFn);
    GroupingState<Long, Long> underlyingValue = underlying.state(namespace, stateTag);
    assertThat(underlyingValue.read(), equalTo(0L));

    underlyingValue.add(1L);
    assertThat(underlyingValue.read(), equalTo(1L));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    GroupingState<Long, Long> copyOnAccessState = internals.state(namespace, stateTag);
    assertThat(copyOnAccessState.read(), equalTo(1L));

    copyOnAccessState.add(4L);
    assertThat(copyOnAccessState.read(), equalTo(5L));
    assertThat(underlyingValue.read(), equalTo(1L));

    GroupingState<Long, Long> reReadUnderlyingValue = underlying.state(namespace, stateTag);
    assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
  }

  @Test
  public void testWatermarkHoldStateWithUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    TimestampCombiner timestampCombiner = TimestampCombiner.EARLIEST;

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<WatermarkHoldState> stateTag =
        StateTags.watermarkStateInternal("wmstate", timestampCombiner);
    WatermarkHoldState underlyingValue = underlying.state(namespace, stateTag);
    assertThat(underlyingValue.read(), nullValue());

    underlyingValue.add(new Instant(250L));
    assertThat(underlyingValue.read(), equalTo(new Instant(250L)));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);
    WatermarkHoldState copyOnAccessState = internals.state(namespace, stateTag);
    assertThat(copyOnAccessState.read(), equalTo(new Instant(250L)));

    copyOnAccessState.add(new Instant(100L));
    assertThat(copyOnAccessState.read(), equalTo(new Instant(100L)));
    assertThat(underlyingValue.read(), equalTo(new Instant(250L)));

    copyOnAccessState.add(new Instant(500L));
    assertThat(copyOnAccessState.read(), equalTo(new Instant(100L)));

    WatermarkHoldState reReadUnderlyingValue = underlying.state(namespace, stateTag);
    assertThat(underlyingValue.read(), equalTo(reReadUnderlyingValue.read()));
  }

  @Test
  public void testCommitWithoutUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = internals.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");
    assertThat(stringBag.read(), containsInAnyOrder("baz", "bar"));

    internals.commit();

    BagState<String> reReadStringBag = internals.state(namespace, bagTag);
    assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));
    assertThat(internals.isEmpty(), is(false));
  }

  @Test
  public void testCommitWithUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = underlying.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");

    internals.commit();
    BagState<String> reReadStringBag = internals.state(namespace, bagTag);
    assertThat(reReadStringBag.read(), containsInAnyOrder("baz", "bar"));

    reReadStringBag.add("spam");

    BagState<String> underlyingState = underlying.state(namespace, bagTag);
    assertThat(underlyingState.read(), containsInAnyOrder("spam", "bar", "baz"));
    assertThat(underlyingState, is(theInstance(stringBag)));
    assertThat(internals.isEmpty(), is(false));
  }

  @Test
  public void testCommitWithClearedInUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> secondUnderlying =
        spy(CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying));
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, secondUnderlying);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = underlying.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");
    stringBag.clear();
    // We should not read through the cleared bag
    secondUnderlying.commit();

    // Should not be visible
    stringBag.add("foo");

    internals.commit();
    BagState<String> internalsStringBag = internals.state(namespace, bagTag);
    assertThat(internalsStringBag.read(), emptyIterable());
    verify(secondUnderlying, never()).state(namespace, bagTag);
    assertThat(internals.isEmpty(), is(false));
  }

  @Test
  public void testCommitWithOverwrittenUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = underlying.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");

    BagState<String> internalsState = internals.state(namespace, bagTag);
    internalsState.add("eggs");
    internalsState.add("ham");
    internalsState.add("0x00ff00");
    internalsState.add("&");

    internals.commit();

    BagState<String> reReadInternalState = internals.state(namespace, bagTag);
    assertThat(
        reReadInternalState.read(),
        containsInAnyOrder("bar", "baz", "0x00ff00", "eggs", "&", "ham"));
    BagState<String> reReadUnderlyingState = underlying.state(namespace, bagTag);
    assertThat(reReadUnderlyingState.read(), containsInAnyOrder("bar", "baz"));
  }

  @Test
  public void testCommitWithAddedUnderlying() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);

    internals.commit();

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = underlying.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");

    BagState<String> internalState = internals.state(namespace, bagTag);
    assertThat(internalState.read(), emptyIterable());

    BagState<String> reReadUnderlyingState = underlying.state(namespace, bagTag);
    assertThat(reReadUnderlyingState.read(), containsInAnyOrder("bar", "baz"));
  }

  @Test
  public void testCommitWithEmptyTableIsEmpty() {
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    internals.commit();

    assertThat(internals.isEmpty(), is(true));
  }

  @Test
  public void testCommitWithOnlyClearedValuesIsEmpty() {
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = internals.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("foo");
    stringBag.clear();

    internals.commit();

    assertThat(internals.isEmpty(), is(true));
  }

  @Test
  public void testCommitWithEmptyNewAndFullUnderlyingIsNotEmpty() {
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, underlying);

    StateNamespace namespace = new StateNamespaceForTest("foo");
    StateTag<BagState<String>> bagTag = StateTags.bag("foo", StringUtf8Coder.of());
    BagState<String> stringBag = underlying.state(namespace, bagTag);
    assertThat(stringBag.read(), emptyIterable());

    stringBag.add("bar");
    stringBag.add("baz");

    internals.commit();
    assertThat(internals.isEmpty(), is(false));
  }

  @Test
  public void testGetEarliestWatermarkHoldAfterCommit() {
    BoundedWindow first =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(2048L);
          }
        };
    BoundedWindow second =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(689743L);
          }
        };
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);

    StateTag<WatermarkHoldState> firstHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState firstHold =
        internals.state(StateNamespaces.window(null, first), firstHoldAddress);
    firstHold.add(new Instant(22L));

    StateTag<WatermarkHoldState> secondHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState secondHold =
        internals.state(StateNamespaces.window(null, second), secondHoldAddress);
    secondHold.add(new Instant(2L));

    internals.commit();
    assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(2L)));
  }

  @Test
  public void testGetEarliestWatermarkHoldWithEarliestInUnderlyingTable() {
    BoundedWindow first =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(2048L);
          }
        };
    BoundedWindow second =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(689743L);
          }
        };
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);
    StateTag<WatermarkHoldState> firstHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState firstHold =
        underlying.state(StateNamespaces.window(null, first), firstHoldAddress);
    firstHold.add(new Instant(22L));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying("foo", underlying.commit());

    StateTag<WatermarkHoldState> secondHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState secondHold =
        internals.state(StateNamespaces.window(null, second), secondHoldAddress);
    secondHold.add(new Instant(244L));

    internals.commit();
    assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(22L)));
  }

  @Test
  public void testGetEarliestWatermarkHoldWithEarliestInNewTable() {
    BoundedWindow first =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(2048L);
          }
        };
    BoundedWindow second =
        new BoundedWindow() {
          @Override
          public Instant maxTimestamp() {
            return new Instant(689743L);
          }
        };
    CopyOnAccessInMemoryStateInternals<String> underlying =
        CopyOnAccessInMemoryStateInternals.withUnderlying("foo", null);
    StateTag<WatermarkHoldState> firstHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState firstHold =
        underlying.state(StateNamespaces.window(null, first), firstHoldAddress);
    firstHold.add(new Instant(224L));

    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying("foo", underlying.commit());

    StateTag<WatermarkHoldState> secondHoldAddress =
        StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST);
    WatermarkHoldState secondHold =
        internals.state(StateNamespaces.window(null, second), secondHoldAddress);
    secondHold.add(new Instant(24L));

    internals.commit();
    assertThat(internals.getEarliestWatermarkHold(), equalTo(new Instant(24L)));
  }

  @Test
  public void testGetEarliestHoldBeforeCommit() {
    CopyOnAccessInMemoryStateInternals<String> internals =
        CopyOnAccessInMemoryStateInternals.withUnderlying(key, null);

    internals
        .state(
            StateNamespaces.global(),
            StateTags.watermarkStateInternal("foo", TimestampCombiner.EARLIEST))
        .add(new Instant(1234L));

    thrown.expect(IllegalStateException.class);
    thrown.expectMessage(CopyOnAccessInMemoryStateInternals.class.getSimpleName());
    thrown.expectMessage("Can't get the earliest watermark hold");
    thrown.expectMessage("before it is committed");

    internals.getEarliestWatermarkHold();
  }
}
