Add basic tests for VersionedMetaData updates

Change-Id: I96e0b5d09f37375276ba67a94cbcc78879f465bf

javatests/com/google/gerrit/server/git/VersionedMetaDataTest.java

@@ -0,0 +1,200 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed 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 com.google.gerrit.server.git;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Streams;
+import com.google.gerrit.common.TimeUtil;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
+import com.google.gerrit.testing.TestTimeUtil;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Optional;
+import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.internal.storage.dfs.DfsRepositoryDescription;
+import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
+import org.eclipse.jgit.lib.CommitBuilder;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.lib.PersonIdent;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevSort;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class VersionedMetaDataTest {
+  // If you're considering fleshing out this test and making it more comprehensive, please consider
+  // instead coming up with a replacement interface for
+  // VersionedMetaData/BatchMetaDataUpdate/MetaDataUpdate that is easier to use correctly.
+
+  private static final TimeZone TZ = TimeZone.getTimeZone("America/Los_Angeles");
+
+  private Project.NameKey project;
+  private Repository repo;
+
+  @Before
+  public void setUp() {
+    TestTimeUtil.resetWithClockStep(1, TimeUnit.SECONDS);
+    project = new Project.NameKey("repo");
+    repo = new InMemoryRepository(new DfsRepositoryDescription(project.get()));
+  }
+
+  @After
+  public void tearDown() {
+    TestTimeUtil.useSystemTime();
+  }
+
+  @Test
+  public void singleUpdate() throws Exception {
+    MyMetaData d = load(0);
+    d.setIncrement(3);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(3, "Increment conf.value by 3");
+  }
+
+  @Test
+  public void noOpNoSetter() throws Exception {
+    MyMetaData d = load(0);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(0);
+  }
+
+  @Test
+  public void noOpWithSetter() throws Exception {
+    MyMetaData d = load(0);
+    d.setIncrement(0);
+    d.commit(newMetaDataUpdate());
+    // First commit is actually not a no-op because it creates an empty config file.
+    assertMyMetaData(0, "Increment conf.value by 0");
+
+    d = load(0);
+    d.setIncrement(0);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(0, "Increment conf.value by 0");
+  }
+
+  @Test
+  public void multipleSeparateUpdatesWithSameObject() throws Exception {
+    MyMetaData d = load(0);
+    d.setIncrement(1);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(1, "Increment conf.value by 1");
+    d.setIncrement(2);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(3, "Increment conf.value by 1", "Increment conf.value by 2");
+  }
+
+  @Test
+  public void multipleSeparateUpdatesWithDifferentObject() throws Exception {
+    MyMetaData d = load(0);
+    d.setIncrement(1);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(1, "Increment conf.value by 1");
+
+    d = load(1);
+    d.setIncrement(2);
+    d.commit(newMetaDataUpdate());
+    assertMyMetaData(3, "Increment conf.value by 1", "Increment conf.value by 2");
+  }
+
+  private MyMetaData load(int expectedValue) throws Exception {
+    MyMetaData d = new MyMetaData();
+    d.load(repo);
+    assertThat(d.getValue()).isEqualTo(expectedValue);
+    return d;
+  }
+
+  private MetaDataUpdate newMetaDataUpdate() {
+    MetaDataUpdate u = new MetaDataUpdate(GitReferenceUpdated.DISABLED, project, repo, null);
+    PersonIdent author = new PersonIdent("J. Author", "author@example.com", TimeUtil.nowTs(), TZ);
+    u.getCommitBuilder().setAuthor(author);
+    u.getCommitBuilder()
+        .setCommitter(
+            new PersonIdent(
+                "M. Committer", "committer@example.com", author.getWhen(), author.getTimeZone()));
+    return u;
+  }
+
+  private void assertMyMetaData(int expectedValue, String... expectedLog) throws Exception {
+    MyMetaData d = load(expectedValue);
+    assertThat(log(d)).containsExactlyElementsIn(Arrays.asList(expectedLog)).inOrder();
+  }
+
+  private ImmutableList<String> log(MyMetaData d) throws Exception {
+    try (RevWalk rw = new RevWalk(repo)) {
+      Ref ref = repo.exactRef(d.getRefName());
+      if (ref == null) {
+        return ImmutableList.of();
+      }
+      rw.sort(RevSort.REVERSE);
+      rw.setRetainBody(true);
+      rw.markStart(rw.parseCommit(ref.getObjectId()));
+      return Streams.stream(rw).map(RevCommit::getFullMessage).collect(toImmutableList());
+    }
+  }
+
+  private static class MyMetaData extends VersionedMetaData {
+    private static final String CONFIG_FILE = "my.config";
+    private static final String SECTION = "conf";
+    private static final String NAME = "value";
+
+    @Override
+    protected String getRefName() {
+      return "refs/my/config";
+    }
+
+    private int curr;
+    private Optional<Integer> increment = Optional.empty();
+
+    @Override
+    protected void onLoad() throws IOException, ConfigInvalidException {
+      Config cfg = readConfig(CONFIG_FILE);
+      curr = cfg.getInt(SECTION, null, NAME, 0);
+    }
+
+    int getValue() {
+      return curr;
+    }
+
+    void setIncrement(int increment) {
+      checkArgument(increment >= 0, "increment must be positive: %s", increment);
+      this.increment = Optional.of(increment);
+    }
+
+    @Override
+    protected boolean onSave(CommitBuilder cb) throws IOException, ConfigInvalidException {
+      // Two ways to produce a no-op: don't call setIncrement, and call setIncrement(0);
+      if (!increment.isPresent()) {
+        return false;
+      }
+      Config cfg = readConfig(CONFIG_FILE);
+      cfg.setInt(SECTION, null, NAME, cfg.getInt(SECTION, null, NAME, 0) + increment.get());
+      cb.setMessage(String.format("Increment %s.%s by %d", SECTION, NAME, increment.get()));
+      saveConfig(CONFIG_FILE, cfg);
+      increment = Optional.empty();
+      return true;
+    }
+  }
+}