add functional test

test/functional/interface_rpc.py

@@ -8,6 +8,8 @@
 from test_framework.authproxy import JSONRPCException
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_greater_than_or_equal
+from threading import Thread
+import subprocess
 
 def expect_http_status(expected_http_status, expected_rpc_code,
                        fcn, *args):
@@ -18,6 +20,20 @@ def expect_http_status(expected_http_status, expected_rpc_code,
         assert_equal(exc.error["code"], expected_rpc_code)
         assert_equal(exc.http_status, expected_http_status)
 
+got_exceeded_error = False
+def test_work_queue_getblock(node):
+    global got_exceeded_error
+    for _ in range(400):
+        if got_exceeded_error:
+            break
+        try:
+            node.cli('getrpcinfo').send_cli()
+        except subprocess.CalledProcessError as e:
+            if e.output != 'error: Server response: Work queue depth exceeded\n':
+                raise AssertionError("Unexpected cli error: :{}:".format(e.output))
+            got_exceeded_error = True
+            break
+
 class RPCInterfaceTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
@@ -67,10 +83,26 @@ def test_http_status_codes(self):
         expect_http_status(404, -32601, self.nodes[0].invalidmethod)
         expect_http_status(500, -8, self.nodes[0].getblockhash, 42)
 
+    def test_work_queue_exceeded(self):
+        global got_exceeded_error
+        self.restart_node(0,['-rpcworkqueue=1'])
+        threads = []
+        for _ in range(5):
+            t = Thread(target=test_work_queue_getblock, args=(self.nodes[0], ))
+            t.start()
+            threads.append(t)
+            if got_exceeded_error:
+                break
+        for t in threads:
+            t.join()
+        # This likely just means more threads are needed.
+        assert(got_exceeded_error)
+
     def run_test(self):
         self.test_getrpcinfo()
         self.test_batch_request()
         self.test_http_status_codes()
+        self.test_work_queue_exceeded()
 
 
 if __name__ == '__main__':