Fix quick start test failure (#480)

The tests started failing due to a break in demo_server dependencies.

This change implements the following:
1) Resolve flask import issue - pin dependency to an earlier version.
2) Add more debugging output to the quick start script to be able to
diagnose similar failures from build logs.

demo_server/requirements.txt

@@ -1,4 +1,6 @@
 flask==1.1.2
 flask-restplus==0.13.0
 Flask-SQLAlchemy==2.5.1
+itsdangerous==2.0.1
 Werkzeug==0.16.0
+

restler/end_to_end_tests/test_quick_start.py

@@ -12,6 +12,7 @@ import sys
 import os
 import subprocess
 import shutil
+import glob
 from pathlib import Path
 
 RESTLER_WORKING_DIR = 'restler_working_dir'
@@ -27,6 +28,7 @@ if __name__ == '__main__':
     demo_server_process = subprocess.Popen([sys.executable, demo_server_path],
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.STDOUT)
+
     os.chdir(curr)
 
     swagger_path = Path('demo_server', 'swagger.json')
@@ -41,7 +43,7 @@ if __name__ == '__main__':
         )
         # Kill demo server
         demo_server_process.terminate()
-
+        demo_server_out, _ = demo_server_process.communicate()
         # Check if restler-quick-start succeeded
         if output.stderr:
             raise QuickStartFailedException(f"Failing because stderr was detected after running restler-quick-start:\n{output.stderr!s}")
@@ -51,11 +53,27 @@ if __name__ == '__main__':
             raise QuickStartFailedException(f"Failing because restler-quick-start exited with a non-zero return code: {output.returncode!s}")
 
         stdout = str(output.stdout)
+
         if 'Request coverage (successful / total): 6 / 6' not in stdout or\
         'No bugs were found.' not in stdout or\
         'Task Test succeeded.' not in stdout:
+            print(f"Demo server output: {demo_server_out}")
+
             stdout = stdout.replace('\\r\\n', '\r\n')
-            raise QuickStartFailedException(f"Failing because expected output was not found:\n{stdout}")
+            # Print the engine logs to the console
+            out_file_path = os.path.join(curr, RESTLER_WORKING_DIR, 'Test', 'EngineStdOut.txt')
+            err_file_path = os.path.join(curr, RESTLER_WORKING_DIR, 'Test', 'EngineStdErr.txt')
+            results_dir = os.path.join(curr, RESTLER_WORKING_DIR, 'Test', 'RestlerResults')
+            # Return the newest experiments directory in RestlerResults
+            net_log_dir = max(glob.glob(os.path.join(results_dir, 'experiment*/')), key=os.path.getmtime)
+            net_log_path = glob.glob(os.path.join(net_log_dir, 'logs', f'network.testing.*.1.txt'))[0]
+            with open(out_file_path) as of, open(err_file_path) as ef, open(net_log_path) as nf:
+                out = of.read()
+                err = ef.read()
+                net_log = nf.read()
+
+            raise QuickStartFailedException(f"Failing because expected output was not found:\n{stdout}{out}{err}{net_log}")
     finally:
         # Delete the working directory that was created during restler quick start
         shutil.rmtree(RESTLER_WORKING_DIR)
+