[PATCH] D25168: [lit] Compare to None using identity, not equality

[Brian Gesiak via llvm-commits]

modocache created this revision.
modocache added reviewers: ddunbar, echristo, beanz.
modocache added a subscriber: llvm-commits.
Herald added a subscriber: mehdi_amini.

In Python, `None` is a singleton, so checking whether a variable is
`None` may be done with `is` or `is not`. This has a slight advantage
over equiality comparisons `== None` and `!= None`, since `__eq__` may
be overridden in Python to produce sometimes unexpected results.

Using `is None` and `is not None` is also recommended practice in
https://www.python.org/dev/peps/pep-0008:

> Comparisons to singletons like `None` should always be done with `is` or

  `is not`, never the equality operators.


https://reviews.llvm.org/D25168

Files:
  utils/lit/lit/TestRunner.py
  utils/lit/lit/main.py


Index: utils/lit/lit/main.py
===================================================================
--- utils/lit/lit/main.py
+++ utils/lit/lit/main.py
@@ -309,7 +309,7 @@
         userParams[name] = val
 
     # Decide what the requested maximum indvidual test time should be
-    if opts.maxIndividualTestTime != None:
+    if opts.maxIndividualTestTime is not None:
         maxIndividualTestTime = opts.maxIndividualTestTime
     else:
         # Default is zero
@@ -340,7 +340,7 @@
     # After test discovery the configuration might have changed
     # the maxIndividualTestTime. If we explicitly set this on the
     # command line then override what was set in the test configuration
-    if opts.maxIndividualTestTime != None:
+    if opts.maxIndividualTestTime is not None:
         if opts.maxIndividualTestTime != litConfig.maxIndividualTestTime:
             litConfig.note(('The test suite configuration requested an individual'
                 ' test timeout of {0} seconds but a timeout of {1} seconds was'
Index: utils/lit/lit/TestRunner.py
===================================================================
--- utils/lit/lit/TestRunner.py
+++ utils/lit/lit/TestRunner.py
@@ -406,7 +406,7 @@
                             data = f.read()
                     except:
                         data = None
-                    if data != None:
+                    if data is not None:
                         output_files.append((name, path, data))
             
         results.append(ShellCommandResult(
@@ -786,16 +786,16 @@
     if exitCode == 0:
         status = Test.PASS
     else:
-        if timeoutInfo == None:
+        if timeoutInfo is None:
             status = Test.FAIL
         else:
             status = Test.TIMEOUT
 
     # Form the output log.
     output = """Script:\n--\n%s\n--\nExit Code: %d\n""" % (
         '\n'.join(script), exitCode)
 
-    if timeoutInfo != None:
+    if timeoutInfo is not None:
         output += """Timeout: %s\n""" % (timeoutInfo,)
     output += "\n"
 


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