Support running from JARs in JGitTestUtil

Buck invokes JUnit tests from compiled JARs, not class directories.
When copying a resource back to the filesystem a jar: style URL is
obtained from the ClassLoader.

Change-Id: I28d702484ec13b0b309b87990da867050e4b5ec6

org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/JGitTestUtil.java

@@ -46,8 +46,10 @@
 package org.eclipse.jgit.junit;
 
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
 import java.lang.reflect.Method;
@@ -124,13 +126,44 @@ public abstract class JGitTestUtil {
 			// loaded previously
 			return new File("tst", fileName);
 		}
+		if ("jar".equals(url.getProtocol())) {
+			try {
+				File tmp = File.createTempFile("tmp_", "_" + fileName);
+				copyTestResource(fileName, tmp);
+				return tmp;
+			} catch (IOException err) {
+				throw new RuntimeException("Cannot create temporary file", err);
+			}
+		}
 		try {
 			return new File(url.toURI());
-		} catch(URISyntaxException e) {
+		} catch (IllegalArgumentException e) {
+			throw new IllegalArgumentException(e.getMessage() + " " + url);
+		} catch (URISyntaxException e) {
 			return new File(url.getPath());
 		}
 	}
 
+	public static void copyTestResource(String name, File dest)
+			throws IOException {
+		URL url = cl().getResource(CLASSPATH_TO_RESOURCES + name);
+		if (url == null)
+			throw new FileNotFoundException(name);
+		InputStream in = url.openStream();
+		try {
+			FileOutputStream out = new FileOutputStream(dest);
+			try {
+				byte[] buf = new byte[4096];
+				for (int n; (n = in.read(buf)) > 0;)
+					out.write(buf, 0, n);
+			} finally {
+				out.close();
+			}
+		} finally {
+			in.close();
+		}
+	}
+
 	private static ClassLoader cl() {
 		return JGitTestUtil.class.getClassLoader();
 	}

org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/SampleDataRepositoryTestCase.java

@@ -66,11 +66,11 @@ public abstract class SampleDataRepositoryTestCase extends RepositoryTestCase {
 		};
 		final File packDir = new File(db.getObjectDatabase().getDirectory(), "pack");
 		for (String n : packs) {
-			copyFile(JGitTestUtil.getTestResourceFile(n + ".pack"), new File(packDir, n + ".pack"));
-			copyFile(JGitTestUtil.getTestResourceFile(n + ".idx"), new File(packDir, n + ".idx"));
+			JGitTestUtil.copyTestResource(n + ".pack", new File(packDir, n + ".pack"));
+			JGitTestUtil.copyTestResource(n + ".idx", new File(packDir, n + ".idx"));
 		}
 
-		copyFile(JGitTestUtil.getTestResourceFile("packed-refs"), new File(db
-				.getDirectory(), "packed-refs"));
+		JGitTestUtil.copyTestResource("packed-refs",
+				new File(db.getDirectory(), "packed-refs"));
 	}
 }