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diff --git a/indra/test/chained_callback.h b/indra/test/chained_callback.h
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+/**
+ * @file   chained_callback.h
+ * @author Nat Goodspeed
+ * @date   2020-01-03
+ * @brief  Subclass of tut::callback used for chaining callbacks.
+ * 
+ * $LicenseInfo:firstyear=2020&license=viewerlgpl$
+ * Copyright (c) 2020, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_CHAINED_CALLBACK_H)
+#define LL_CHAINED_CALLBACK_H
+
+#include "lltut.h"
+
+/**
+ * Derive your TUT callback from chained_callback instead of tut::callback to
+ * ensure that multiple such callbacks can coexist in a given test executable.
+ * The relevant callback method will be called for each callback instance in
+ * reverse order of the instance's link() methods being called: the most
+ * recently link()ed callback will be called first, then the previous, and so
+ * forth.
+ *
+ * Obviously, for this to work, all relevant callbacks must be derived from
+ * chained_callback instead of tut::callback. Given that, control should reach
+ * each of them regardless of their construction order. The chain is
+ * guaranteed to stop because the first link() call will link to test_runner's
+ * default_callback, which is simply an instance of the callback() base class.
+ *
+ * The rule for deriving from chained_callback is that you may override any of
+ * its virtual methods, but your override must at some point call the
+ * corresponding chained_callback method.
+ */
+class chained_callback: public tut::callback
+{
+public:
+    /**
+     * Instead of calling tut::test_runner::set_callback(&your_callback), call
+     * your_callback.link();
+     * This uses the canonical instance of tut::test_runner.
+     */
+    void link()
+    {
+        link(tut::runner.get());
+    }
+
+    /**
+     * If for some reason you have a different instance of test_runner...
+     */
+    void link(tut::test_runner& runner)
+    {
+        // Since test_runner's constructor sets a default callback,
+        // get_callback() will always return a reference to a valid callback
+        // instance.
+        mPrev = &runner.get_callback();
+        runner.set_callback(this);
+    }
+
+    /**
+     * Called when new test run started.
+     */
+    virtual void run_started()
+    {
+        mPrev->run_started();
+    }
+
+    /**
+     * Called when a group started
+     * @param name Name of the group
+     */
+    virtual void group_started(const std::string& name)
+    {
+        mPrev->group_started(name);
+    }
+
+    /**
+     * Called when a test finished.
+     * @param tr Test results.
+     */
+    virtual void test_completed(const tut::test_result& tr)
+    {
+        mPrev->test_completed(tr);
+    }
+
+    /**
+     * Called when a group is completed
+     * @param name Name of the group
+     */
+    virtual void group_completed(const std::string& name)
+    {
+        mPrev->group_completed(name);
+    }
+
+    /**
+     * Called when all tests in run completed.
+     */
+    virtual void run_completed()
+    {
+        mPrev->run_completed();
+    }
+
+private:
+    tut::callback* mPrev;
+};
+
+#endif /* ! defined(LL_CHAINED_CALLBACK_H) */