Add unit test for FIFOEvictor

Add unit test for client side FIFO Evictor.

pr-link: #13339
change-id: cid-1b039bec331d002a3db73df943e6f741892a4231

core/client/fs/src/test/java/alluxio/client/file/cache/FIFOEvictorTest.java

@@ -0,0 +1,89 @@
+/*
+ * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
+ * (the "License"). You may not use this work except in compliance with the License, which is
+ * available at www.apache.org/licenses/LICENSE-2.0
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied, as more fully set forth in the License.
+ *
+ * See the NOTICE file distributed with this work for information regarding copyright ownership.
+ */
+
+package alluxio.client.file.cache;
+
+import alluxio.ConfigurationTestUtils;
+import alluxio.client.file.cache.evictor.FIFOEvictor;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Tests for the {@link FIFOEvictor} class.
+ */
+public final class FIFOEvictorTest {
+  private FIFOEvictor mEvictor;
+  private final PageId mFirst = new PageId("1L", 2L);
+  private final PageId mSecond = new PageId("3L", 4L);
+  private final PageId mThird = new PageId("5L", 6L);
+  private final PageId mFourth = new PageId("7L", 8L);
+
+  /**
+   * Sets up the instances.
+   */
+  @Before
+  public void before() {
+    mEvictor = new FIFOEvictor(ConfigurationTestUtils.defaults());
+  }
+
+  @Test
+  public void evictPutOrder() {
+    mEvictor.updateOnPut(mFirst);
+    mEvictor.updateOnPut(mSecond);
+    mEvictor.updateOnPut(mThird);
+    mEvictor.updateOnPut(mFourth);
+    Assert.assertEquals(mFirst, mEvictor.evict());
+  }
+
+  @Test
+  public void evictPutAndGetOrder() {
+    mEvictor.updateOnPut(mFirst);
+    mEvictor.updateOnPut(mSecond);
+    mEvictor.updateOnPut(mThird);
+    mEvictor.updateOnPut(mFourth);
+    mEvictor.updateOnGet(mFourth);
+    mEvictor.updateOnGet(mFourth);
+    mEvictor.updateOnGet(mFourth);
+    Assert.assertEquals(mFirst, mEvictor.evict());
+  }
+
+  @Test
+  public void evictAfterDelete() {
+    mEvictor.updateOnPut(mFirst);
+    mEvictor.updateOnPut(mSecond);
+    mEvictor.updateOnPut(mThird);
+    mEvictor.updateOnPut(mFourth);
+    mEvictor.updateOnDelete(mSecond);
+    Assert.assertEquals(mFirst, mEvictor.evict());
+    mEvictor.updateOnDelete(mFirst);
+    Assert.assertEquals(mThird, mEvictor.evict());
+  }
+
+  @Test
+  public void evictEmpty() {
+    Assert.assertNull(mEvictor.evict());
+  }
+
+  @Test
+  public void evictAllGone() {
+    mEvictor.updateOnPut(mFirst);
+    mEvictor.updateOnPut(mSecond);
+    mEvictor.updateOnPut(mThird);
+    mEvictor.updateOnPut(mFourth);
+    mEvictor.updateOnDelete(mFirst);
+    mEvictor.updateOnDelete(mSecond);
+    mEvictor.updateOnDelete(mThird);
+    mEvictor.updateOnDelete(mFourth);
+    Assert.assertNull(mEvictor.evict());
+  }
+}