1 files changed, 68 insertions, 0 deletions
diff --git a/src/main/java/org/junit/rules/ExternalResource.java b/src/main/java/org/junit/rules/ExternalResource.java
new file mode 100644
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+++ b/src/main/java/org/junit/rules/ExternalResource.java
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+package org.junit.rules;
+
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * A base class for Rules (like TemporaryFolder) that set up an external
+ * resource before a test (a file, socket, server, database connection, etc.),
+ * and guarantee to tear it down afterward:
+ * 
+ * <pre>
+ * public static class UsesExternalResource {
+ * 	Server myServer= new Server();
+ * 
+ * 	&#064;Rule
+ * 	public ExternalResource resource= new ExternalResource() {
+ * 		&#064;Override
+ * 		protected void before() throws Throwable {
+ * 			myServer.connect();
+ * 		};
+ * 
+ * 		&#064;Override
+ * 		protected void after() {
+ * 			myServer.disconnect();
+ * 		};
+ * 	};
+ * 
+ * 	&#064;Test
+ * 	public void testFoo() {
+ * 		new Client().run(myServer);
+ * 	}
+ * }
+ * </pre>
+ */
+public abstract class ExternalResource implements TestRule {
+	public Statement apply(Statement base, Description description) {
+		return statement(base);
+	}
+
+	private Statement statement(final Statement base) {
+		return new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				before();
+				try {
+					base.evaluate();
+				} finally {
+					after();
+				}
+			}
+		};
+	}
+
+	/**
+	 * Override to set up your specific external resource.
+	 * @throws if setup fails (which will disable {@code after}
+	 */
+	protected void before() throws Throwable {
+		// do nothing
+	}
+
+	/**
+	 * Override to tear down your specific external resource.
+	 */
+	protected void after() {
+		// do nothing
+	}
+}