Revert "Remove DisableOnDebug (new in 4.12) as it is not support..."

Revert submission 1601635

Reason for revert: b/181123058
Reverted Changes:
I8f5cd1266:Remove support for stuck threads
Ifdb59336d:Remove DisableOnDebug (new in 4.12) as it is not s...
I6abae5aed:Extra generic type information to aid certain java...
I5ec909df6:Upgrade external/junit to 4.13.2

Change-Id: I464bf4512b5e19f37ba69ac42a5e9c22f61bc7d1

2 files changed, 125 insertions, 1 deletions

diff --git a/README.version b/README.version
index d7a4bf1..43903b2 100644
--- a/README.version
+++ b/README.version
@@ -4,4 +4,3 @@ BugComponent: 40416
 
 Local Changes:
     Extra generic type information to aid certain javacs.
-    Remove DisableOnDebug (new in 4.12) as it is not supported on Android
diff --git a/src/main/java/org/junit/rules/DisableOnDebug.java b/src/main/java/org/junit/rules/DisableOnDebug.java
new file mode 100644
index 0000000..3bca103
--- /dev/null
+++ b/src/main/java/org/junit/rules/DisableOnDebug.java
@@ -0,0 +1,125 @@
+package org.junit.rules;
+
+import java.util.List;
+
+import org.junit.internal.management.ManagementFactory;
+import org.junit.internal.management.RuntimeMXBean;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * The {@code DisableOnDebug} Rule allows you to label certain rules to be
+ * disabled when debugging.
+ * <p>
+ * The most illustrative use case is for tests that make use of the
+ * {@link Timeout} rule, when ran in debug mode the test may terminate on
+ * timeout abruptly during debugging. Developers may disable the timeout, or
+ * increase the timeout by making a code change on tests that need debugging and
+ * remember revert the change afterwards or rules such as {@link Timeout} that
+ * may be disabled during debugging may be wrapped in a {@code DisableOnDebug}.
+ * <p>
+ * The important benefit of this feature is that you can disable such rules
+ * without any making any modifications to your test class to remove them during
+ * debugging.
+ * <p>
+ * This does nothing to tackle timeouts or time sensitive code under test when
+ * debugging and may make this less useful in such circumstances.
+ * <p>
+ * Example usage:
+ * 
+ * <pre>
+ * public static class DisableTimeoutOnDebugSampleTest {
+ * 
+ *     &#064;Rule
+ *     public TestRule timeout = new DisableOnDebug(new Timeout(20));
+ * 
+ *     &#064;Test
+ *     public void myTest() {
+ *         int i = 0;
+ *         assertEquals(0, i); // suppose you had a break point here to inspect i
+ *     }
+ * }
+ * </pre>
+ * 
+ * @since 4.12
+ */
+public class DisableOnDebug implements TestRule {
+    private final TestRule rule;
+    private final boolean debugging;
+
+    /**
+     * Create a {@code DisableOnDebug} instance with the timeout specified in
+     * milliseconds.
+     * 
+     * @param rule to disable during debugging
+     */
+    public DisableOnDebug(TestRule rule) {
+        this(rule, ManagementFactory.getRuntimeMXBean()
+                .getInputArguments());
+    }
+
+    /**
+     * Visible for testing purposes only.
+     * 
+     * @param rule the rule to disable during debugging
+     * @param inputArguments
+     *            arguments provided to the Java runtime
+     */
+    DisableOnDebug(TestRule rule, List<String> inputArguments) {
+        this.rule = rule;
+        debugging = isDebugging(inputArguments);
+    }
+
+    /**
+     * @see TestRule#apply(Statement, Description)
+     */
+    public Statement apply(Statement base, Description description) {
+        if (debugging) {
+            return base;
+        } else {
+            return rule.apply(base, description);
+        }
+    }
+
+    /**
+     * Parses arguments passed to the runtime environment for debug flags
+     * <p>
+     * Options specified in:
+     * <ul>
+     * <li>
+     * <a href="http://docs.oracle.com/javase/6/docs/technotes/guides/jpda/conninv.html#Invocation"
+     * >javase-6</a></li>
+     * <li><a href="http://docs.oracle.com/javase/7/docs/technotes/guides/jpda/conninv.html#Invocation"
+     * >javase-7</a></li>
+     * <li><a href="http://docs.oracle.com/javase/8/docs/technotes/guides/jpda/conninv.html#Invocation"
+     * >javase-8</a></li>
+     * 
+     * 
+     * @param arguments
+     *            the arguments passed to the runtime environment, usually this
+     *            will be {@link RuntimeMXBean#getInputArguments()}
+     * @return true if the current JVM was started in debug mode, false
+     *         otherwise.
+     */
+    private static boolean isDebugging(List<String> arguments) {
+        for (final String argument : arguments) {
+            if ("-Xdebug".equals(argument) || argument.startsWith("-agentlib:jdwp")) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns {@code true} if the JVM is in debug mode. This method may be used
+     * by test classes to take additional action to disable code paths that
+     * interfere with debugging if required.
+     * 
+     * @return {@code true} if the current JVM is in debug mode, {@code false}
+     *         otherwise
+     */
+    public boolean isDebugging() {
+        return debugging;
+    }
+
+}