diff --git a/core/api/src/test/java/org/onlab/onos/net/intent/TestTools.java b/core/api/src/test/java/org/onlab/onos/net/intent/TestTools.java
new file mode 100644
index 0000000..f22585e
--- /dev/null
+++ b/core/api/src/test/java/org/onlab/onos/net/intent/TestTools.java
@@ -0,0 +1,126 @@
+package org.onlab.onos.net.intent;
+
+import static org.junit.Assert.fail;
+
+/**
+ * Set of test tools.
+ */
+public final class TestTools {
+
+    // Disallow construction
+    private TestTools() {
+    }
+
+    /**
+     * Utility method to pause the current thread for the specified number of
+     * milliseconds.
+     *
+     * @param ms number of milliseconds to pause
+     */
+    public static void delay(int ms) {
+        try {
+            Thread.sleep(ms);
+        } catch (InterruptedException e) {
+            fail("unexpected interrupt");
+        }
+    }
+
+    /**
+     * Periodically runs the given runnable, which should contain a series of
+     * test assertions until all the assertions succeed, in which case it will
+     * return, or until the the time expires, in which case it will throw the
+     * first failed assertion error.
+     *
+     * @param start start time, in millis since start of epoch from which the
+     *        duration will be measured
+     * @param delay initial delay (in milliseconds) before the first assertion
+     *        attempt
+     * @param step delay (in milliseconds) between successive assertion
+     *        attempts
+     * @param duration number of milliseconds beyond the given start time,
+     *        after which the failed assertions will be propagated and allowed
+     *        to fail the test
+     * @param assertions runnable housing the test assertions
+     */
+    public static void assertAfter(long start, int delay, int step,
+                                   int duration, Runnable assertions) {
+        delay(delay);
+        while (true) {
+            try {
+                assertions.run();
+                break;
+            } catch (AssertionError e) {
+                if (System.currentTimeMillis() - start > duration) {
+                    throw e;
+                }
+            }
+            delay(step);
+        }
+    }
+
+    /**
+     * Periodically runs the given runnable, which should contain a series of
+     * test assertions until all the assertions succeed, in which case it will
+     * return, or until the the time expires, in which case it will throw the
+     * first failed assertion error.
+     * <p>
+     * The start of the period is the current time.
+     *
+     * @param delay initial delay (in milliseconds) before the first assertion
+     *        attempt
+     * @param step delay (in milliseconds) between successive assertion
+     *        attempts
+     * @param duration number of milliseconds beyond the current time time,
+     *        after which the failed assertions will be propagated and allowed
+     *        to fail the test
+     * @param assertions runnable housing the test assertions
+     */
+    public static void assertAfter(int delay, int step, int duration,
+                                   Runnable assertions) {
+        assertAfter(System.currentTimeMillis(), delay, step, duration,
+                    assertions);
+    }
+
+    /**
+     * Periodically runs the given runnable, which should contain a series of
+     * test assertions until all the assertions succeed, in which case it will
+     * return, or until the the time expires, in which case it will throw the
+     * first failed assertion error.
+     * <p>
+     * The start of the period is the current time and the first assertion
+     * attempt is delayed by the value of {@code step} parameter.
+     *
+     * @param step delay (in milliseconds) between successive assertion
+     *        attempts
+     * @param duration number of milliseconds beyond the current time time,
+     *        after which the failed assertions will be propagated and allowed
+     *        to fail the test
+     * @param assertions runnable housing the test assertions
+     */
+    public static void assertAfter(int step, int duration,
+                                   Runnable assertions) {
+        assertAfter(step, step, duration, assertions);
+    }
+
+    /**
+     * Periodically runs the given runnable, which should contain a series of
+     * test assertions until all the assertions succeed, in which case it will
+     * return, or until the the time expires, in which case it will throw the
+     * first failed assertion error.
+     * <p>
+     * The start of the period is the current time and each successive
+     * assertion attempt is delayed by at least 10 milliseconds unless the
+     * {@code duration} is less than that, in which case the one and only
+     * assertion is made after that delay.
+     *
+     * @param duration number of milliseconds beyond the current time,
+     *        after which the failed assertions will be propagated and allowed
+     *        to fail the test
+     * @param assertions runnable housing the test assertions
+     */
+    public static void assertAfter(int duration, Runnable assertions) {
+        int step = Math.min(duration, Math.max(10, duration / 10));
+        assertAfter(step, duration, assertions);
+    }
+
+}