Add patchset retrieval to test API of changes

The returned patchset object doesn't contain many attributes yet. It's
main purpose is currently to retrieve the PatchSet.Id or the commit
SHA-1 of the current patchset.

The introduced patchset-level in the API will also serve as basis for
any actions we want to define on patchsets like the addition of
comments.

Change-Id: I7259099b13873ea5cedff9b5bde613a78bd02e30

java/com/google/gerrit/acceptance/GerritServer.java

@@ -32,6 +32,7 @@ import com.google.gerrit.acceptance.testsuite.account.AccountOperations;
 import com.google.gerrit.acceptance.testsuite.account.AccountOperationsImpl;
 import com.google.gerrit.acceptance.testsuite.change.ChangeOperations;
 import com.google.gerrit.acceptance.testsuite.change.ChangeOperationsImpl;
+import com.google.gerrit.acceptance.testsuite.change.PerPatchsetOperationsImpl;
 import com.google.gerrit.acceptance.testsuite.group.GroupOperations;
 import com.google.gerrit.acceptance.testsuite.group.GroupOperationsImpl;
 import com.google.gerrit.acceptance.testsuite.project.ProjectOperations;
@@ -509,6 +510,7 @@ public class GerritServer implements AutoCloseable {
             bind(ProjectOperations.class).to(ProjectOperationsImpl.class);
             bind(RequestScopeOperations.class).to(RequestScopeOperationsImpl.class);
             bind(ChangeOperations.class).to(ChangeOperationsImpl.class);
+            factory(PerPatchsetOperationsImpl.Factory.class);
             factory(PushOneCommit.Factory.class);
             install(InProcessProtocol.module());
             install(new NoSshModule());

java/com/google/gerrit/acceptance/testsuite/change/ChangeOperations.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.acceptance.testsuite.change;
 
 import com.google.gerrit.entities.Change;
+import com.google.gerrit.entities.PatchSet;
 
 /**
  * An aggregation of operations on changes for test purposes.
@@ -95,5 +96,20 @@ public interface ChangeOperations {
      * @return builder to create a new patchset
      */
     TestPatchsetCreation.Builder newPatchset();
+
+    /**
+     * Starts the fluent chain for querying or modifying a patchset. Please see the methods of
+     * {@link PerPatchsetOperations} for details on possible operations.
+     *
+     * @return an aggregation of operations on a specific patchset
+     */
+    PerPatchsetOperations patchset(PatchSet.Id patchsetId);
+
+    /**
+     * Like {@link #patchset(PatchSet.Id)} but for the current patchset.
+     *
+     * @return an aggregation of operations on a specific patchset
+     */
+    PerPatchsetOperations currentPatchset();
   }
 }

java/com/google/gerrit/acceptance/testsuite/change/ChangeOperationsImpl.java

@@ -79,6 +79,7 @@ public class ChangeOperationsImpl implements ChangeOperations {
   private final BatchUpdate.Factory batchUpdateFactory;
   private final ProjectCache projectCache;
   private final ChangeFinder changeFinder;
+  private final PerPatchsetOperationsImpl.Factory perPatchsetOperationsFactory;
 
   @Inject
   public ChangeOperationsImpl(
@@ -91,7 +92,8 @@ public class ChangeOperationsImpl implements ChangeOperations {
       @GerritPersonIdent PersonIdent serverIdent,
       BatchUpdate.Factory batchUpdateFactory,
       ProjectCache projectCache,
-      ChangeFinder changeFinder) {
+      ChangeFinder changeFinder,
+      PerPatchsetOperationsImpl.Factory perPatchsetOperationsFactory) {
     this.seq = seq;
     this.changeInserterFactory = changeInserterFactory;
     this.patchsetInserterFactory = patchsetInserterFactory;
@@ -102,6 +104,7 @@ public class ChangeOperationsImpl implements ChangeOperations {
     this.batchUpdateFactory = batchUpdateFactory;
     this.projectCache = projectCache;
     this.changeFinder = changeFinder;
+    this.perPatchsetOperationsFactory = perPatchsetOperationsFactory;
   }
 
   @Override
@@ -393,5 +396,17 @@ public class ChangeOperationsImpl implements ChangeOperations {
       patchSetInserter.setMessage(String.format("Uploaded patchset %d.", patchsetId.get()));
       return patchSetInserter;
     }
+
+    @Override
+    public PerPatchsetOperations patchset(PatchSet.Id patchsetId) {
+      return perPatchsetOperationsFactory.create(getChangeNotes(), patchsetId);
+    }
+
+    @Override
+    public PerPatchsetOperations currentPatchset() {
+      ChangeNotes changeNotes = getChangeNotes();
+      return perPatchsetOperationsFactory.create(
+          changeNotes, changeNotes.getChange().currentPatchSetId());
+    }
   }
 }

java/com/google/gerrit/acceptance/testsuite/change/PerPatchsetOperations.java

@@ -0,0 +1,28 @@
+// Copyright (C) 2020 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.acceptance.testsuite.change;
+
+/** An aggregation of methods on a specific patchset. */
+public interface PerPatchsetOperations {
+
+  /**
+   * Retrieves the patchset.
+   *
+   * <p><strong>Note:</strong> This call will fail with an exception if the requested patchset
+   * doesn't exist.
+   *
+   * @return the corresponding {@code TestPatchset}
+   */
+  TestPatchset get();
+}

java/com/google/gerrit/acceptance/testsuite/change/PerPatchsetOperationsImpl.java

@@ -0,0 +1,48 @@
+// Copyright (C) 2020 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.acceptance.testsuite.change;
+
+import com.google.gerrit.entities.PatchSet;
+import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.inject.Inject;
+import com.google.inject.assistedinject.Assisted;
+
+/**
+ * The implementation of {@link PerPatchsetOperations}.
+ *
+ * <p>There is only one implementation of {@link PerPatchsetOperations}. Nevertheless, we keep the
+ * separation between interface and implementation to enhance clarity.
+ */
+public class PerPatchsetOperationsImpl implements PerPatchsetOperations {
+  private final ChangeNotes changeNotes;
+  private final PatchSet.Id patchsetId;
+
+  public interface Factory {
+    PerPatchsetOperationsImpl create(ChangeNotes changeNotes, PatchSet.Id patchsetId);
+  }
+
+  @Inject
+  private PerPatchsetOperationsImpl(
+      @Assisted ChangeNotes changeNotes, @Assisted PatchSet.Id patchsetId) {
+    this.changeNotes = changeNotes;
+    this.patchsetId = patchsetId;
+  }
+
+  @Override
+  public TestPatchset get() {
+    PatchSet patchset = changeNotes.getPatchSets().get(patchsetId);
+    return TestPatchset.builder().patchsetId(patchsetId).commitId(patchset.commitId()).build();
+  }
+}

java/com/google/gerrit/acceptance/testsuite/change/TestPatchset.java

@@ -0,0 +1,43 @@
+// Copyright (C) 2020 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.acceptance.testsuite.change;
+
+import com.google.auto.value.AutoValue;
+import com.google.gerrit.entities.PatchSet;
+import org.eclipse.jgit.lib.ObjectId;
+
+/** Representation of a patchset used for testing purposes. */
+@AutoValue
+public abstract class TestPatchset {
+
+  /** The numeric patchset ID. */
+  public abstract PatchSet.Id patchsetId();
+
+  /** The commit SHA-1 of the patchset. */
+  public abstract ObjectId commitId();
+
+  static Builder builder() {
+    return new AutoValue_TestPatchset.Builder();
+  }
+
+  @AutoValue.Builder
+  abstract static class Builder {
+    abstract Builder patchsetId(PatchSet.Id patchsetId);
+
+    abstract Builder commitId(ObjectId commitId);
+
+    abstract TestPatchset build();
+  }
+}

javatests/com/google/gerrit/acceptance/testsuite/change/ChangeOperationsImplTest.java

@@ -305,6 +305,33 @@ public class ChangeOperationsImplTest extends AbstractDaemonTest {
     assertThat(change.changeId()).isEqualTo("I0123456789012345678901234567890123456789");
   }
 
+  @Test
+  public void currentPatchsetOfExistingChangeCanBeRetrieved() throws Exception {
+    Change.Id changeId = changeOperations.newChange().create();
+
+    TestPatchset patchset = changeOperations.change(changeId).currentPatchset().get();
+
+    ChangeInfo expectedChange = getChangeFromServer(changeId);
+    String expectedCommitId = expectedChange.currentRevision;
+    int expectedPatchsetNumber = expectedChange.revisions.get(expectedCommitId)._number;
+    assertThat(patchset.commitId()).isEqualTo(ObjectId.fromString(expectedCommitId));
+    assertThat(patchset.patchsetId()).isEqualTo(PatchSet.id(changeId, expectedPatchsetNumber));
+  }
+
+  @Test
+  public void earlierPatchsetOfExistingChangeCanBeRetrieved() {
+    Change.Id changeId = changeOperations.newChange().create();
+    PatchSet.Id earlierPatchsetId =
+        changeOperations.change(changeId).currentPatchset().get().patchsetId();
+    PatchSet.Id currentPatchsetId = changeOperations.change(changeId).newPatchset().create();
+
+    TestPatchset earlierPatchset =
+        changeOperations.change(changeId).patchset(earlierPatchsetId).get();
+
+    assertThat(earlierPatchset.patchsetId()).isEqualTo(earlierPatchsetId);
+    assertThat(earlierPatchset.patchsetId()).isNotEqualTo(currentPatchsetId);
+  }
+
   @Test
   public void newPatchsetCanBeCreatedWithoutSpecifyingAnyParameters() throws Exception {
     Change.Id changeId = changeOperations.newChange().create();