diff --git a/javatests/com/google/gitiles/VisibilityCacheTest.java b/javatests/com/google/gitiles/VisibilityCacheTest.java
new file mode 100644
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+++ b/javatests/com/google/gitiles/VisibilityCacheTest.java
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+/*
+ * Copyright (C) 2019, Google LLC.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */ package com.google.gitiles;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Set;
+import org.eclipse.jgit.internal.storage.dfs.DfsRepositoryDescription;
+import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
+import org.eclipse.jgit.junit.TestRepository;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.transport.resolver.ServiceNotAuthorizedException;
+import org.eclipse.jgit.transport.resolver.ServiceNotEnabledException;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class VisibilityCacheTest {
+
+  private InMemoryRepository repo;
+  private GitilesAccess access = new FakeGitilesAccess();
+
+  private RevCommit baseCommit;
+  private RevCommit commit1;
+  private RevCommit commit2;
+  private RevCommit commitA;
+  private RevCommit commitB;
+  private RevCommit commitC;
+
+  private VisibilityCache visibilityCache;
+  private RevWalk walk;
+
+  @Before
+  public void setUp() throws Exception {
+    /**
+     * master (branch not visible)
+     *
+     * <p>commitC | commit2 commitB | | commit1 commitA <--- refs/tags/v0.1 \ / \ / baseCommit
+     */
+    repo = new InMemoryRepository(new DfsRepositoryDescription());
+    TestRepository<InMemoryRepository> git = new TestRepository<>(repo);
+    baseCommit = git.commit().message("baseCommit").create();
+    commit1 = git.commit().parent(baseCommit).message("commit1").create();
+    commit2 = git.commit().parent(commit1).message("commit2").create();
+
+    commitA = git.commit().parent(baseCommit).message("commitA").create();
+    commitB = git.commit().parent(commitA).message("commitB").create();
+    commitC = git.commit().parent(commitB).message("commitC").create();
+
+    git.update("master", commit2);
+    git.update("refs/tags/v0.1", commitA);
+
+    visibilityCache = new VisibilityCache(true);
+    walk = new RevWalk(repo);
+    walk.setRetainBody(false);
+  }
+
+  @After
+  public void tearDown() {
+    repo.close();
+  }
+
+  @Test
+  public void isTip() throws IOException {
+    ObjectId[] known = new ObjectId[0];
+    assertThat(visibilityCache.isVisible(repo, walk, access, commit2.getId(), known)).isTrue();
+  }
+
+  @Test
+  public void reachableFromHeads() throws Exception {
+    ObjectId[] known = new ObjectId[0];
+    assertThat(visibilityCache.isVisible(repo, walk, access, commit1.getId(), known)).isTrue();
+  }
+
+  @Test
+  public void reachableFromTags() throws Exception {
+    ObjectId[] known = new ObjectId[0];
+    assertThat(visibilityCache.isVisible(repo, walk, access, commitA.getId(), known)).isTrue();
+  }
+
+  @Test
+  public void unreachableFromAnyTip() throws Exception {
+    ObjectId[] known = new ObjectId[0];
+    assertThat(visibilityCache.isVisible(repo, walk, access, commitB.getId(), known)).isFalse();
+  }
+
+  @Test
+  public void reachableFromAnotherId() throws Exception {
+    ObjectId[] known = new ObjectId[] {commitC.getId()};
+    assertThat(visibilityCache.isVisible(repo, walk, access, commitB.getId(), known)).isTrue();
+  }
+
+  private static class FakeGitilesAccess implements GitilesAccess {
+    @Override
+    public Map<String, RepositoryDescription> listRepositories(String prefix, Set<String> branches)
+        throws ServiceNotEnabledException, ServiceNotAuthorizedException, IOException {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Object getUserKey() {
+      return "Test";
+    }
+
+    @Override
+    public String getRepositoryName() {
+      return "VisibilityCache-Test";
+    }
+
+    @Override
+    public RepositoryDescription getRepositoryDescription() throws IOException {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Config getConfig() throws IOException {
+      throw new UnsupportedOperationException();
+    }
+  }
+}