ObjectIdMatcher: Custom matcher for sets of ObjectIds

Parsed requests represent object ids (SHA1) in ObjectId instances but tests
use strings for those ids because they are easier to define.

Create a custom matcher that hides the conversion from string to
ObjectId. Note that this reverses the existing code conversion (it was
transforming ObjectIds into string).

This produces more readable code, consistent with the other hamcrest
assertions.

Change-Id: I47ba1d25557d791fe74fb93c740ff7de9923cc00
Signed-off-by: Ivan Frade <ifrade@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/ObjectIdMatcher.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2018, 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 org.eclipse.jgit.transport;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.Sets;
+import org.hamcrest.Description;
+import org.hamcrest.Factory;
+import org.hamcrest.Matcher;
+import org.hamcrest.TypeSafeMatcher;
+
+/**
+ * Multiple tests check that a collection of ObjectIds contain certain SHA1
+ * (written as strings). This matcher hides the ObjectId to string conversion to
+ * make the assertion more readable:
+ *
+ * assertThat(req.getWantsIds(), hasOnlyObjectIds("123123", "234234"));
+ */
+class ObjectIdMatcher extends TypeSafeMatcher<Collection<ObjectId>> {
+
+	private final Set<ObjectId> expectedOids;
+
+	private ObjectIdMatcher(Set<String> oids) {
+		this.expectedOids = oids.stream().map(ObjectId::fromString)
+				.collect(Collectors.toSet());
+	}
+
+	@Override
+	public void describeTo(Description desc) {
+		desc.appendText("Object ids:");
+		desc.appendValueList("<", ",", ">", expectedOids);
+	}
+
+	@Override
+	protected boolean matchesSafely(Collection<ObjectId> resultOids) {
+		return resultOids.containsAll(expectedOids)
+				&& expectedOids.containsAll(resultOids);
+	}
+
+	/**
+	 * Assert that all and only the received {@link ObjectId object ids} are in
+	 * the expected set.
+	 * <p>
+	 * ObjectIds are compared by SHA1.
+	 *
+	 * @param oids
+	 *            Object ids to examine.
+	 * @return true if examined and specified sets contains exactly the same
+	 *         elements.
+	 */
+	@Factory
+	static Matcher<Collection<ObjectId>> hasOnlyObjectIds(
+			String... oids) {
+		return new ObjectIdMatcher(Sets.of(oids));
+	}
+}

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/ProtocolV2ParserTest.java

@@ -48,20 +48,17 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.eclipse.jgit.transport.ObjectIdMatcher.hasOnlyObjectIds;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.util.Collection;
-import java.util.List;
-import java.util.stream.Collectors;
 
 import org.eclipse.jgit.errors.PackProtocolException;
 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.junit.Before;
 import org.junit.Rule;
@@ -139,12 +136,6 @@ public class ProtocolV2ParserTest {
 		return new PacketLineIn(new ByteArrayInputStream(send.toByteArray()));
 	}
 
-	private static List<String> objIdsAsStrings(Collection<ObjectId> objIds) {
-		// TODO(ifrade) Translate this to a matcher, so it would read as
-		// assertThat(req.wantsIds(), hasObjectIds("...", "..."))
-		return objIds.stream().map(ObjectId::name).collect(Collectors.toList());
-	}
-
 	/*
 	 * Succesful fetch with the basic core commands of the protocol.
 	 */
@@ -171,11 +162,11 @@ public class ProtocolV2ParserTest {
 				.contains(GitProtocolConstants.OPTION_INCLUDE_TAG));
 		assertTrue(request.getClientCapabilities()
 				.contains(GitProtocolConstants.CAPABILITY_OFS_DELTA));
-		assertThat(objIdsAsStrings(request.getWantIds()),
-				hasItems("4624442d68ee402a94364191085b77137618633e",
+		assertThat(request.getWantIds(),
+				hasOnlyObjectIds("4624442d68ee402a94364191085b77137618633e",
 						"f900c8326a43303685c46b279b9f70411bff1a4b"));
-		assertThat(objIdsAsStrings(request.getPeerHas()),
-				hasItems("554f6e41067b9e3e565b6988a8294fac1cb78f4b",
+		assertThat(request.getPeerHas(),
+				hasOnlyObjectIds("554f6e41067b9e3e565b6988a8294fac1cb78f4b",
 						"abc760ab9ad72f08209943251b36cb886a578f87"));
 		assertTrue(request.getWantedRefs().isEmpty());
 		assertTrue(request.wasDoneReceived());
@@ -194,8 +185,8 @@ public class ProtocolV2ParserTest {
 				ConfigBuilder.getDefault());
 		FetchV2Request request = parser.parseFetchRequest(pckIn,
 				testRepo.getRepository().getRefDatabase());
-		assertThat(objIdsAsStrings(request.getClientShallowCommits()),
-				hasItems("28274d02c489f4c7e68153056e9061a46f62d7a0",
+		assertThat(request.getClientShallowCommits(),
+				hasOnlyObjectIds("28274d02c489f4c7e68153056e9061a46f62d7a0",
 						"145e683b229dcab9d0e2ccb01b386f9ecc17d29d"));
 		assertTrue(request.getDeepenNotRefs().isEmpty());
 		assertEquals(15, request.getDepth());
@@ -214,8 +205,8 @@ public class ProtocolV2ParserTest {
 				ConfigBuilder.getDefault());
 		FetchV2Request request = parser.parseFetchRequest(pckIn,
 				testRepo.getRepository().getRefDatabase());
-		assertThat(objIdsAsStrings(request.getClientShallowCommits()),
-				hasItems("28274d02c489f4c7e68153056e9061a46f62d7a0",
+		assertThat(request.getClientShallowCommits(),
+				hasOnlyObjectIds("28274d02c489f4c7e68153056e9061a46f62d7a0",
 						"145e683b229dcab9d0e2ccb01b386f9ecc17d29d"));
 		assertThat(request.getDeepenNotRefs(),
 				hasItems("a08595f76159b09d57553e37a5123f1091bb13e7"));
@@ -232,8 +223,8 @@ public class ProtocolV2ParserTest {
 				ConfigBuilder.getDefault());
 		FetchV2Request request = parser.parseFetchRequest(pckIn,
 				testRepo.getRepository().getRefDatabase());
-		assertThat(objIdsAsStrings(request.getClientShallowCommits()),
-				hasItems("28274d02c489f4c7e68153056e9061a46f62d7a0",
+		assertThat(request.getClientShallowCommits(),
+				hasOnlyObjectIds("28274d02c489f4c7e68153056e9061a46f62d7a0",
 						"145e683b229dcab9d0e2ccb01b386f9ecc17d29d"));
 		assertEquals(123123123, request.getDeepenSince());
 	}
@@ -309,9 +300,9 @@ public class ProtocolV2ParserTest {
 		assertThat(request.getWantedRefs().keySet(),
 				hasItems("refs/heads/branchA"));
 		assertEquals(2, request.getWantIds().size());
-		assertThat(objIdsAsStrings(request.getWantIds()),
-				hasItems("e4980cdc48cfa1301493ca94eb70523f6788b819",
-						one.getName()));
+		assertThat(request.getWantIds(), hasOnlyObjectIds(
+				"e4980cdc48cfa1301493ca94eb70523f6788b819",
+				one.getName()));
 	}
 
 	@Test