Add open(File) and wrap(Repository) to Git

When a new Git instance for an exisiting git repository should be
created there are two use-cases: either the application has already a
Repository instance in hand or the application knows where the
repository resides in the filesystem. Two methods are added to
explicitly support these use-cases: wrap(Repository db) and open(File
gitDir)

Change-Id: I2970e4aa8d4602cb1298f01e5b76bf0f96c492e5
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/GitConstructionTest.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2011, Christian Halstrick <christian.halstrick@sap.com>
+ * 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.api;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import java.io.IOException;
+
+import org.eclipse.jgit.api.ListBranchCommand.ListMode;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.RepositoryTestCase;
+import org.junit.Before;
+import org.junit.Test;
+
+public class GitConstructionTest extends RepositoryTestCase {
+	private Repository bareRepo;
+
+	@Override
+	@Before
+	public void setUp() throws Exception {
+		super.setUp();
+		Git git = new Git(db);
+		git.commit().setMessage("initial commit").call();
+		writeTrashFile("Test.txt", "Hello world");
+		git.add().addFilepattern("Test.txt").call();
+		git.commit().setMessage("Initial commit").call();
+
+		bareRepo = Git.cloneRepository().setBare(true)
+				.setURI(db.getDirectory().toURI().toString()).call()
+				.getRepository();
+	}
+
+	@Test
+	public void testWrap() {
+		Git git = Git.wrap(db);
+		assertEquals(1, git.branchList().call().size());
+
+		git = Git.wrap(bareRepo);
+		assertEquals(1, git.branchList().setListMode(ListMode.ALL).call()
+				.size());
+
+		try {
+			Git.wrap(null);
+			fail("Expected exception has not been thrown");
+		} catch (NullPointerException e) {
+			// should not get here
+		}
+	}
+
+	@Test
+	public void testOpen() throws IOException {
+		Git git = Git.open(db.getDirectory());
+		assertEquals(1, git.branchList().call().size());
+
+		git = Git.open(bareRepo.getDirectory());
+		assertEquals(1, git.branchList().setListMode(ListMode.ALL).call()
+				.size());
+
+		git = Git.open(db.getWorkTree());
+		assertEquals(1, git.branchList().setListMode(ListMode.ALL).call()
+				.size());
+
+		try {
+			Git.open(db.getObjectsDirectory());
+			fail("Expected exception has not been thrown");
+		} catch (RepositoryNotFoundException e) {
+			// should not get here
+		}
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/api/Git.java

@@ -43,7 +43,13 @@
  */
 package org.eclipse.jgit.api;
 
+import java.io.File;
+import java.io.IOException;
+
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.RepositoryBuilder;
+import org.eclipse.jgit.lib.RepositoryCache;
+import org.eclipse.jgit.util.FS;
 
 /**
  * Offers a "GitPorcelain"-like API to interact with a git repository.
@@ -79,6 +85,46 @@ public class Git {
 	/** The git repository this class is interacting with */
 	private final Repository repo;
 
+	/**
+	 * @param dir
+	 *            the repository to open. May be either the GIT_DIR, or the
+	 *            working tree directory that contains {@code .git}.
+	 * @return a {@link Git} object for the existing git repository
+	 * @throws IOException
+	 */
+	public static Git open(File dir) throws IOException {
+		return open(dir, FS.DETECTED);
+	}
+
+	/**
+	 * @param dir
+	 *            the repository to open. May be either the GIT_DIR, or the
+	 *            working tree directory that contains {@code .git}.
+	 * @param fs
+	 *            filesystem abstraction to use when accessing the repository.
+	 * @return a {@link Git} object for the existing git repository
+	 * @throws IOException
+	 */
+	public static Git open(File dir, FS fs) throws IOException {
+		RepositoryCache.FileKey key;
+
+		key = RepositoryCache.FileKey.lenient(dir, fs);
+		return wrap(new RepositoryBuilder()
+				.setFS(fs)
+				.setGitDir(key.getFile())
+				.setMustExist(true).build());
+	}
+
+	/**
+	 * @param repo
+	 *            the git repository this class is interacting with.
+	 *            {@code null} is not allowed
+	 * @return a {@link Git} object for the existing git repository
+	 */
+	public static Git wrap(Repository repo) {
+		return new Git(repo);
+	}
+
 	/**
 	 * Returns a command object to execute a {@code clone} command
 	 *
@@ -88,7 +134,7 @@ public class Git {
 	 * @return a {@link CloneCommand} used to collect all optional parameters
 	 *         and to finally execute the {@code clone} command
 	 */
-	static public CloneCommand cloneRepository() {
+	public static CloneCommand cloneRepository() {
 		return new CloneCommand();
 	}