Add --quiet option to suppress demos' output

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/scripts/run_demos.py

@@ -1,44 +1,57 @@
 #!/usr/bin/env python3
 """Run the Mbed TLS demo scripts.
 """
+import argparse
 import glob
 import subprocess
 import sys
 
-def run_demo(demo):
+def run_demo(demo, quiet=False):
     """Run the specified demo script. Return True if it succeeds."""
-    returncode = subprocess.call([demo])
+    args = {}
+    if quiet:
+        args['stdout'] = subprocess.DEVNULL
+        args['stderr'] = subprocess.DEVNULL
+    returncode = subprocess.call([demo], **args)
     return returncode == 0
 
-def run_demos(demos):
+def run_demos(demos, quiet=False):
     """Run the specified demos and print summary information about failures.
 
     Return True if all demos passed and False if a demo fails.
     """
     failures = []
     for demo in demos:
-        print('#### {} ####'.format(demo))
-        success = run_demo(demo)
+        if not quiet:
+            print('#### {} ####'.format(demo))
+        success = run_demo(demo, quiet=quiet)
         if not success:
             failures.append(demo)
-            print('{}: FAIL'.format(demo))
-        print('')
+            if not quiet:
+                print('{}: FAIL'.format(demo))
+        if not quiet:
+            print('')
     successes = len(demos) - len(failures)
     print('{}/{} demos passed'.format(successes, len(demos)))
     if failures:
         print('Failures:', *failures)
     return not failures
 
-def run_all_demos():
+def run_all_demos(quiet=False):
     """Run all the available demos.
 
     Return True if all demos passed and False if a demo fails.
     """
     all_demos = glob.glob('programs/*/*_demo.sh')
-    return run_demos(all_demos)
+    return run_demos(all_demos, quiet=quiet)
 
 def main():
-    success = run_all_demos()
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--quiet', '-q',
+                        action='store_true',
+                        help="suppress the output of demos")
+    options = parser.parse_args()
+    success = run_all_demos(quiet=options.quiet)
     sys.exit(0 if success else 1)
 
 if __name__ == '__main__':