diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/DiffCommandTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/DiffCommandTest.java
index 4ad01cf6f..4f5b50dcc 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/DiffCommandTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/DiffCommandTest.java
@@ -70,32 +70,33 @@ public class DiffCommandTest extends RepositoryTestCase {
 		File folder = new File(db.getWorkTree(), "folder");
 		folder.mkdir();
 		write(new File(folder, "folder.txt"), "folder");
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("Initial commit").call();
-		write(new File(folder, "folder.txt"), "folder change");
-
-		OutputStream out = new ByteArrayOutputStream();
-		List<DiffEntry> entries = git.diff().setOutputStream(out).call();
-		assertEquals(1, entries.size());
-		assertEquals(ChangeType.MODIFY, entries.get(0)
-				.getChangeType());
-		assertEquals("folder/folder.txt", entries.get(0)
-				.getOldPath());
-		assertEquals("folder/folder.txt", entries.get(0)
-				.getNewPath());
-
-		String actual = out.toString();
-		String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
-				+ "index 0119635..95c4c65 100644\n"
-				+ "--- a/folder/folder.txt\n"
-				+ "+++ b/folder/folder.txt\n"
-				+ "@@ -1 +1 @@\n"
-				+ "-folder\n"
-				+ "\\ No newline at end of file\n"
-				+ "+folder change\n"
-				+ "\\ No newline at end of file\n";
-		assertEquals(expected.toString(), actual);
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("Initial commit").call();
+			write(new File(folder, "folder.txt"), "folder change");
+
+			OutputStream out = new ByteArrayOutputStream();
+			List<DiffEntry> entries = git.diff().setOutputStream(out).call();
+			assertEquals(1, entries.size());
+			assertEquals(ChangeType.MODIFY, entries.get(0)
+					.getChangeType());
+			assertEquals("folder/folder.txt", entries.get(0)
+					.getOldPath());
+			assertEquals("folder/folder.txt", entries.get(0)
+					.getNewPath());
+
+			String actual = out.toString();
+			String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
+					+ "index 0119635..95c4c65 100644\n"
+					+ "--- a/folder/folder.txt\n"
+					+ "+++ b/folder/folder.txt\n"
+					+ "@@ -1 +1 @@\n"
+					+ "-folder\n"
+					+ "\\ No newline at end of file\n"
+					+ "+folder change\n"
+					+ "\\ No newline at end of file\n";
+			assertEquals(expected.toString(), actual);
+		}
 	}
 
 	@Test
@@ -103,33 +104,34 @@ public class DiffCommandTest extends RepositoryTestCase {
 		write(new File(db.getWorkTree(), "test.txt"), "test");
 		File folder = new File(db.getWorkTree(), "folder");
 		folder.mkdir();
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("Initial commit").call();
-		write(new File(folder, "folder.txt"), "folder");
-		git.add().addFilepattern(".").call();
-
-		OutputStream out = new ByteArrayOutputStream();
-		List<DiffEntry> entries = git.diff().setOutputStream(out)
-				.setCached(true).call();
-		assertEquals(1, entries.size());
-		assertEquals(ChangeType.ADD, entries.get(0)
-				.getChangeType());
-		assertEquals("/dev/null", entries.get(0)
-				.getOldPath());
-		assertEquals("folder/folder.txt", entries.get(0)
-				.getNewPath());
-
-		String actual = out.toString();
-		String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
-				+ "new file mode 100644\n"
-				+ "index 0000000..0119635\n"
-				+ "--- /dev/null\n"
-				+ "+++ b/folder/folder.txt\n"
-				+ "@@ -0,0 +1 @@\n"
-				+ "+folder\n"
-				+ "\\ No newline at end of file\n";
-		assertEquals(expected.toString(), actual);
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("Initial commit").call();
+			write(new File(folder, "folder.txt"), "folder");
+			git.add().addFilepattern(".").call();
+
+			OutputStream out = new ByteArrayOutputStream();
+			List<DiffEntry> entries = git.diff().setOutputStream(out)
+					.setCached(true).call();
+			assertEquals(1, entries.size());
+			assertEquals(ChangeType.ADD, entries.get(0)
+					.getChangeType());
+			assertEquals("/dev/null", entries.get(0)
+					.getOldPath());
+			assertEquals("folder/folder.txt", entries.get(0)
+					.getNewPath());
+
+			String actual = out.toString();
+			String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
+					+ "new file mode 100644\n"
+					+ "index 0000000..0119635\n"
+					+ "--- /dev/null\n"
+					+ "+++ b/folder/folder.txt\n"
+					+ "@@ -0,0 +1 @@\n"
+					+ "+folder\n"
+					+ "\\ No newline at end of file\n";
+			assertEquals(expected.toString(), actual);
+		}
 	}
 
 	@Test
@@ -138,107 +140,109 @@ public class DiffCommandTest extends RepositoryTestCase {
 		File folder = new File(db.getWorkTree(), "folder");
 		folder.mkdir();
 		write(new File(folder, "folder.txt"), "folder");
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("Initial commit").call();
-		write(new File(folder, "folder.txt"), "folder change");
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("second commit").call();
-		write(new File(folder, "folder.txt"), "second folder change");
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("third commit").call();
-
-		// bad filter
-		DiffCommand diff = git.diff().setShowNameAndStatusOnly(true)
-				.setPathFilter(PathFilter.create("test.txt"))
-				.setOldTree(getTreeIterator("HEAD^^"))
-				.setNewTree(getTreeIterator("HEAD^"));
-		List<DiffEntry> entries = diff.call();
-		assertEquals(0, entries.size());
-
-		// no filter, two commits
-		OutputStream out = new ByteArrayOutputStream();
-		diff = git.diff().setOutputStream(out)
-				.setOldTree(getTreeIterator("HEAD^^"))
-				.setNewTree(getTreeIterator("HEAD^"));
-		entries = diff.call();
-		assertEquals(1, entries.size());
-		assertEquals(ChangeType.MODIFY, entries.get(0).getChangeType());
-		assertEquals("folder/folder.txt", entries.get(0).getOldPath());
-		assertEquals("folder/folder.txt", entries.get(0).getNewPath());
-
-		String actual = out.toString();
-		String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
-				+ "index 0119635..95c4c65 100644\n"
-				+ "--- a/folder/folder.txt\n"
-				+ "+++ b/folder/folder.txt\n"
-				+ "@@ -1 +1 @@\n"
-				+ "-folder\n"
-				+ "\\ No newline at end of file\n"
-				+ "+folder change\n"
-				+ "\\ No newline at end of file\n";
-		assertEquals(expected.toString(), actual);
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("Initial commit").call();
+			write(new File(folder, "folder.txt"), "folder change");
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("second commit").call();
+			write(new File(folder, "folder.txt"), "second folder change");
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("third commit").call();
+
+			// bad filter
+			DiffCommand diff = git.diff().setShowNameAndStatusOnly(true)
+					.setPathFilter(PathFilter.create("test.txt"))
+					.setOldTree(getTreeIterator("HEAD^^"))
+					.setNewTree(getTreeIterator("HEAD^"));
+			List<DiffEntry> entries = diff.call();
+			assertEquals(0, entries.size());
+
+			// no filter, two commits
+			OutputStream out = new ByteArrayOutputStream();
+			diff = git.diff().setOutputStream(out)
+					.setOldTree(getTreeIterator("HEAD^^"))
+					.setNewTree(getTreeIterator("HEAD^"));
+			entries = diff.call();
+			assertEquals(1, entries.size());
+			assertEquals(ChangeType.MODIFY, entries.get(0).getChangeType());
+			assertEquals("folder/folder.txt", entries.get(0).getOldPath());
+			assertEquals("folder/folder.txt", entries.get(0).getNewPath());
+
+			String actual = out.toString();
+			String expected = "diff --git a/folder/folder.txt b/folder/folder.txt\n"
+					+ "index 0119635..95c4c65 100644\n"
+					+ "--- a/folder/folder.txt\n"
+					+ "+++ b/folder/folder.txt\n"
+					+ "@@ -1 +1 @@\n"
+					+ "-folder\n"
+					+ "\\ No newline at end of file\n"
+					+ "+folder change\n"
+					+ "\\ No newline at end of file\n";
+			assertEquals(expected.toString(), actual);
+		}
 	}
 
 	@Test
 	public void testDiffWithPrefixes() throws Exception {
 		write(new File(db.getWorkTree(), "test.txt"), "test");
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("Initial commit").call();
-		write(new File(db.getWorkTree(), "test.txt"), "test change");
-
-		OutputStream out = new ByteArrayOutputStream();
-		git.diff().setOutputStream(out).setSourcePrefix("old/")
-				.setDestinationPrefix("new/")
-				.call();
-
-		String actual = out.toString();
-		String expected = "diff --git old/test.txt new/test.txt\n"
-				+ "index 30d74d2..4dba797 100644\n" + "--- old/test.txt\n"
-				+ "+++ new/test.txt\n" + "@@ -1 +1 @@\n" + "-test\n"
-				+ "\\ No newline at end of file\n" + "+test change\n"
-				+ "\\ No newline at end of file\n";
-		assertEquals(expected.toString(), actual);
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("Initial commit").call();
+			write(new File(db.getWorkTree(), "test.txt"), "test change");
+
+			OutputStream out = new ByteArrayOutputStream();
+			git.diff().setOutputStream(out).setSourcePrefix("old/")
+					.setDestinationPrefix("new/").call();
+
+			String actual = out.toString();
+			String expected = "diff --git old/test.txt new/test.txt\n"
+					+ "index 30d74d2..4dba797 100644\n" + "--- old/test.txt\n"
+					+ "+++ new/test.txt\n" + "@@ -1 +1 @@\n" + "-test\n"
+					+ "\\ No newline at end of file\n" + "+test change\n"
+					+ "\\ No newline at end of file\n";
+			assertEquals(expected.toString(), actual);
+		}
 	}
 
 	@Test
 	public void testDiffWithNegativeLineCount() throws Exception {
 		write(new File(db.getWorkTree(), "test.txt"),
 				"0\n1\n2\n3\n4\n5\n6\n7\n8\n9");
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		git.commit().setMessage("Initial commit").call();
-		write(new File(db.getWorkTree(), "test.txt"),
-				"0\n1\n2\n3\n4a\n5\n6\n7\n8\n9");
-
-		OutputStream out = new ByteArrayOutputStream();
-		git.diff().setOutputStream(out).setContextLines(1)
-				.call();
-
-		String actual = out.toString();
-		String expected = "diff --git a/test.txt b/test.txt\n"
-				+ "index f55b5c9..c5ec8fd 100644\n" + "--- a/test.txt\n"
-				+ "+++ b/test.txt\n" + "@@ -4,3 +4,3 @@\n" + " 3\n" + "-4\n"
-				+ "+4a\n" + " 5\n";
-		assertEquals(expected.toString(), actual);
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("Initial commit").call();
+			write(new File(db.getWorkTree(), "test.txt"),
+					"0\n1\n2\n3\n4a\n5\n6\n7\n8\n9");
+
+			OutputStream out = new ByteArrayOutputStream();
+			git.diff().setOutputStream(out).setContextLines(1).call();
+
+			String actual = out.toString();
+			String expected = "diff --git a/test.txt b/test.txt\n"
+					+ "index f55b5c9..c5ec8fd 100644\n" + "--- a/test.txt\n"
+					+ "+++ b/test.txt\n" + "@@ -4,3 +4,3 @@\n" + " 3\n" + "-4\n"
+					+ "+4a\n" + " 5\n";
+			assertEquals(expected.toString(), actual);
+		}
 	}
 
 	@Test
 	public void testNoOutputStreamSet() throws Exception {
 		File file = writeTrashFile("test.txt", "a");
 		assertTrue(file.setLastModified(file.lastModified() - 5000));
-		Git git = new Git(db);
-		git.add().addFilepattern(".").call();
-		write(file, "b");
-
-		List<DiffEntry> diffs = git.diff().call();
-		assertNotNull(diffs);
-		assertEquals(1, diffs.size());
-		DiffEntry diff = diffs.get(0);
-		assertEquals(ChangeType.MODIFY, diff.getChangeType());
-		assertEquals("test.txt", diff.getOldPath());
-		assertEquals("test.txt", diff.getNewPath());
+		try (Git git = new Git(db)) {
+			git.add().addFilepattern(".").call();
+			write(file, "b");
+
+			List<DiffEntry> diffs = git.diff().call();
+			assertNotNull(diffs);
+			assertEquals(1, diffs.size());
+			DiffEntry diff = diffs.get(0);
+			assertEquals(ChangeType.MODIFY, diff.getChangeType());
+			assertEquals("test.txt", diff.getOldPath());
+			assertEquals("test.txt", diff.getNewPath());
+		}
 	}
 
 	private AbstractTreeIterator getTreeIterator(String name)
@@ -247,8 +251,9 @@ public class DiffCommandTest extends RepositoryTestCase {
 		if (id == null)
 			throw new IllegalArgumentException(name);
 		final CanonicalTreeParser p = new CanonicalTreeParser();
-		try (ObjectReader or = db.newObjectReader()) {
-			p.reset(or, new RevWalk(db).parseTree(id));
+		try (ObjectReader or = db.newObjectReader();
+				RevWalk rw = new RevWalk(db)) {
+			p.reset(or, rw.parseTree(id));
 			return p;
 		}
 	}