diff -r 000000000000 -r 6474c204b198 mobile/android/base/tests/helpers/JavascriptMessageParser.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/tests/helpers/JavascriptMessageParser.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,100 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.tests.helpers;
+
+import org.mozilla.gecko.Assert;
+
+import junit.framework.AssertionFailedError;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Route messages from Javascript's head.js test framework into Java's
+ * Mochitest framework.
+ */
+public final class JavascriptMessageParser {
+
+    /**
+    * The Javascript test harness sends test events to Java.
+    * Each such test event is wrapped in a Robocop:JS event.
+    */
+    public static final String EVENT_TYPE = "Robocop:JS";
+
+    // Messages matching this pattern are handled specially.  Messages not
+    // matching this pattern are still printed. This pattern should be able
+    // to handle having multiple lines in a message.
+    private static final Pattern testMessagePattern =
+        Pattern.compile("TEST-([A-Z\\-]+) \\| (.*?) \\| (.*)", Pattern.DOTALL);
+
+    private final Assert asserter;
+    // Used to help print stack traces neatly.
+    private String lastTestName = "";
+    // Have we seen a message saying the test is finished?
+    private boolean testFinishedMessageSeen = false;
+    private final boolean endOnAssertionFailure;
+
+    /**
+     * Constructs a message parser for test result messages sent from JavaScript. When seeing an
+     * assertion failure, the message parser can use the given {@link org.mozilla.gecko.Assert}
+     * instance to immediately end the test (typically if the underlying JS framework is not able
+     * to end the test itself) or to swallow the Errors - this functionality is determined by the
+     * <code>endOnAssertionFailure</code> parameter.
+     *
+     * @param asserter The Assert instance to which test results should be passed.
+     * @param endOnAssertionFailure
+     *        true if the test should end if we see a JS assertion failure, false otherwise.
+     */
+    public JavascriptMessageParser(final Assert asserter, final boolean endOnAssertionFailure) {
+        this.asserter = asserter;
+        this.endOnAssertionFailure = endOnAssertionFailure;
+    }
+
+    public boolean isTestFinished() {
+        return testFinishedMessageSeen;
+    }
+
+    public void logMessage(final String str) {
+        final Matcher m = testMessagePattern.matcher(str.trim());
+
+        if (m.matches()) {
+            final String type = m.group(1);
+            final String name = m.group(2);
+            final String message = m.group(3);
+
+            if ("INFO".equals(type)) {
+                asserter.info(name, message);
+                testFinishedMessageSeen = testFinishedMessageSeen ||
+                                          "exiting test".equals(message);
+            } else if ("PASS".equals(type)) {
+                asserter.ok(true, name, message);
+            } else if ("UNEXPECTED-FAIL".equals(type)) {
+                try {
+                    asserter.ok(false, name, message);
+                } catch (AssertionFailedError e) {
+                    // Above, we call the assert, allowing it to log.
+                    // Now we can end the test, if applicable.
+                    if (this.endOnAssertionFailure) {
+                        throw e;
+                    }
+                    // Otherwise, swallow the Error. The JS framework we're
+                    // logging messages from is likely capable of ending tests
+                    // when it needs to, and we want to see all of its failures,
+                    // not just the first one!
+                }
+            } else if ("KNOWN-FAIL".equals(type)) {
+                asserter.todo(false, name, message);
+            } else if ("UNEXPECTED-PASS".equals(type)) {
+                asserter.todo(true, name, message);
+            }
+
+            lastTestName = name;
+        } else {
+            // Generally, these extra lines are stack traces from failures,
+            // so we print them with the name of the last test seen.
+            asserter.info(lastTestName, str.trim());
+        }
+    }
+}