CHOP-661: add and use code to listen on next available server port.

In indra/llmessage/tests/testrunner.py, introduce new freeport() function to
try a caller-specified expression (such as instantiating an object that will
listen on a server port) with a range of candidate port numbers until the
expression produces a value instead of EADDRINUSE exception.
Change test_llsdmessage_peer.py and test_llxmlrpc_peer.py to use freeport() to
construct their server class inline BEFORE launching the thread that will run
it, then pass that server's serve_forever method to daemon thread. Also set
os.environ["PORT"] to selected environment variable before running subject
test program.
In indra/llmessage/tests/commtest.h, introduce commtest_data::getport() to
read port number from specified environment variable, throwing exception if
variable not set or non-numeric. Construct default LLHost from getport("PORT")
instead of hardcoded constant.
Change indra/newview/tests/llxmlrpclistener_test.cpp to use commtest_data::
getport("PORT") instead of hardcoded constant. Also use LLSD::with() rather
than older LLSD::insert() syntax.
HOWEVER -- I am irritated to discover that llxmlrpclistener_test IS NOT RUN or
even built by newview/CMakeLists.txt! It's not even commented out -- it's
entirely deleted! I am determined to restore this test. However, as it will
take some fiddling with new link-time dependencies, that will be a separate
commit.

1 files changed, 18 insertions, 8 deletions

diff --git a/indra/llmessage/tests/test_llsdmessage_peer.py b/indra/llmessage/tests/test_llsdmessage_peer.py
index 580ee7f8b4..cea5032111 100644
--- a/indra/llmessage/tests/test_llsdmessage_peer.py
+++ b/indra/llmessage/tests/test_llsdmessage_peer.py
@@ -38,7 +38,7 @@ mydir = os.path.dirname(__file__)       # expected to be .../indra/llmessage/tes
 sys.path.insert(0, os.path.join(mydir, os.pardir, os.pardir, "lib", "python"))
 from indra.util.fastest_elementtree import parse as xml_parse
 from indra.base import llsd
-from testrunner import run, debug
+from testrunner import freeport, run, debug
 
 class TestHTTPRequestHandler(BaseHTTPRequestHandler):
     """This subclass of BaseHTTPRequestHandler is to receive and echo
@@ -97,6 +97,10 @@ class TestHTTPRequestHandler(BaseHTTPRequestHandler):
             self.wfile.write(response)
         else:                           # fail requested
             status = data.get("status", 500)
+            # self.responses maps an int status to a (short, long) pair of
+            # strings. We want the longer string. That's why we pass a string
+            # pair to get(): the [1] will select the second string, whether it
+            # came from self.responses or from our default pair.
             reason = data.get("reason",
                                self.responses.get(status,
                                                   ("fail requested",
@@ -113,11 +117,17 @@ class TestHTTPRequestHandler(BaseHTTPRequestHandler):
         # Suppress error output as well
         pass
 
-class TestHTTPServer(Thread):
-    def run(self):
-        httpd = HTTPServer(('127.0.0.1', 8000), TestHTTPRequestHandler)
-        debug("Starting HTTP server...\n")
-        httpd.serve_forever()
-
 if __name__ == "__main__":
-    sys.exit(run(server=TestHTTPServer(name="httpd"), *sys.argv[1:]))
+    # Instantiate an HTTPServer(TestHTTPRequestHandler) on the first free port
+    # in the specified port range. Doing this inline is better than in a
+    # daemon thread: if it blows up here, we'll get a traceback. If it blew up
+    # in some other thread, the traceback would get eaten and we'd run the
+    # subject test program anyway.
+    httpd, port = freeport(xrange(8000, 8020),
+                           lambda port: HTTPServer(('127.0.0.1', port), TestHTTPRequestHandler))
+    # Pass the selected port number to the subject test program via the
+    # environment. We don't want to impose requirements on the test program's
+    # command-line parsing -- and anyway, for C++ integration tests, that's
+    # performed in TUT code rather than our own.
+    os.environ["PORT"] = str(port)
+    sys.exit(run(server=Thread(name="httpd", target=httpd.serve_forever), *sys.argv[1:]))