skip unless mephistor decorator (#4957)

parlai/utils/testing.py

@@ -62,6 +62,14 @@
     FAIRSEQ_AVAILABLE = False
 
 
+try:
+    import mephisto  # noqa: F401
+
+    MEPHISTO_AVAILABLE = True
+except ImportError:
+    MEPHISTO_AVAILABLE = False
+
+
 def is_this_circleci():
     """
     Return if we are currently running in CircleCI.
@@ -130,6 +138,13 @@ def skipUnlessFairseq(testfn, reason='fairseq not installed'):
     return unittest.skipUnless(FAIRSEQ_AVAILABLE, reason)(testfn)
 
 
+def skipUnlessMephisto(testfn, reason='mephisto not installed'):
+    """
+    Decorate a test to skip unless mephisto is installed.
+    """
+    return unittest.skipUnless(MEPHISTO_AVAILABLE, reason)(testfn)
+
+
 class retry(object):
     """
     Decorator for flaky tests. Test is run up to ntries times, retrying on failure.