[tools/perf] Provide mechanism to deal with unsatisfied dependencies

Some external module dependencies, notably numpy and pandas, are
required by some command line perf tools to work properly. And these
are normally satisfied by the vpython environment.

However vpython is not always available, e.g. on ChromeOs, so we
provide a mechanism to safely dismiss the respective import errors
and skip tests that cannot be run due to the lack of these modules.

Doing in this in preparation for the migration of soundwave out
of catapult/experimental and into tools/perf; since that includes
many other tests that also depend on these external modules.

TBR=achuith@chromium.org

Bug: 922030
Bug: 921762
Change-Id: I162e8e232484a5f9c8f919426ad86c6d0ad2e428
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1494887Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Juan Antonio Navarro Pérez <perezju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637648}

tools/perf/cli_tools/flakiness_cli/analysis.py

@@ -4,11 +4,8 @@
 
 import fnmatch
 
-import numpy  # pylint: disable=import-error
-try:
-  import pandas  # pylint: disable=import-error
-except ImportError:
-  pass
+from core.external_modules import numpy
+from core.external_modules import pandas
 
 
 SECONDS_IN_A_DAY = 60 * 60 * 24

tools/perf/cli_tools/flakiness_cli/analysis_unittest.py

@@ -4,13 +4,13 @@
 
 import unittest
 
-from telemetry import decorators
 from cli_tools.flakiness_cli import analysis
 from cli_tools.flakiness_cli import frames
+from core.external_modules import pandas
 
 
+@unittest.skipIf(pandas is None, 'pandas not available')
 class TestAnalysis(unittest.TestCase):
-  @decorators.Disabled('chromeos')  # crbug.com/921762
   def testFilterBy(self):
     builders = frames.pandas.DataFrame.from_records([
       ['chromium.perf', 'my-mac-bot', 'common_tests'],

tools/perf/cli_tools/flakiness_cli/frames.py

@@ -7,10 +7,7 @@
 import datetime
 import os
 
-try:
-  import pandas  # pylint: disable=import-error
-except ImportError:
-  pass
+from core.external_modules import pandas
 
 
 CACHE_DIR = os.path.abspath(os.path.join(

tools/perf/cli_tools/flakiness_cli/frames_unittest.py

@@ -10,12 +10,12 @@ import unittest
 
 import mock
 
-from telemetry import decorators
 from cli_tools.flakiness_cli import frames
+from core.external_modules import pandas
 
 
+@unittest.skipIf(pandas is None, 'pandas not available')
 class TestDataFrames(unittest.TestCase):
-  @decorators.Disabled('chromeos')  # crbug.com/921762
   def testBuildersDataFrame(self):
     sample_data = {
         'masters': [
@@ -109,7 +109,6 @@ class TestDataFrames(unittest.TestCase):
     self.assertItemsEqual(
         list(frames._IterTestResults(tests_dict)), expected)
 
-  @decorators.Disabled('chromeos')  # crbug.com/921762
   def testTestResultsDataFrame(self):
     data = {
         'android-bot': {
@@ -154,7 +153,6 @@ class TestDataFrames(unittest.TestCase):
     self.assertEqual(len(selection), 1)
     self.assertTrue(selection.iloc[0]['result'], 'N')
 
-  @decorators.Disabled('chromeos')  # crbug.com/921762
   def testTestResultsDataFrame_empty(self):
     data = {
         'android-bot': {
@@ -181,7 +179,6 @@ class TestDataFrames(unittest.TestCase):
     with self.assertRaises(AssertionError):
       frames.TestResultsDataFrame(data)
 
-  @decorators.Disabled('chromeos')  # crbug.com/921762
   def testGetWithCache(self):
     def make_frame_1():
       # test_2 was failing.

tools/perf/cli_tools/flakiness_cli/main.py

@@ -7,7 +7,7 @@
 import argparse
 
 from cli_tools.flakiness_cli import analysis
-from cli_tools.flakiness_cli import core
+from cli_tools.flakiness_cli import cached_api
 
 
 def Main():
@@ -32,7 +32,7 @@ def Main():
       ' with flakiness above this level.')
   args = parser.parse_args()
 
-  configs = core.GetBuilders()
+  configs = cached_api.GetBuilders()
   configs = analysis.FilterBy(configs, master=args.master,
                               builder=args.builder, test_type=args.test_type)
   if configs.empty:
@@ -40,7 +40,7 @@ def Main():
 
   dfs = []
   for row in configs.itertuples():
-    df = core.GetTestResults(row.master, row.builder, row.test_type)
+    df = cached_api.GetTestResults(row.master, row.builder, row.test_type)
     df = analysis.FilterBy(df, test_suite=args.test_suite)
     if df.empty:
       continue

tools/perf/core/external_modules.py

+# Copyright 2019 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Allow importing external modules which may be missing in some platforms.
+
+These modules are normally provided by the vpython environment manager. But
+some platforms, e.g. CromeOs, do not have access to this facility.
+
+To be safe, instead of e.g.:
+
+    import pandas
+
+clients should do:
+
+    from core.external_modules import pandas
+
+Tests that require pandas to work can be skipped as follows:
+
+    from core.external_modules import pandas
+
+
+    @unittest.skipIf(pandas is None, 'pandas not available')
+    class TestsForMyModule(unittest.TestCase):
+      def testSomeBehavior(self):
+        # test some behavior that requires pandas module.
+
+Finally, scripts that to work properly require any of these external
+dependencies should call:
+
+    from core import external_modules
+
+    if __name__ == '__main__':
+      external_modules.RequireModules()
+      # the rest of your script here.
+
+to exit early with a suitable error message if the dependencies are not
+satisfied.
+"""
+
+import sys
+
+try:
+  import numpy  # pylint: disable=import-error
+except ImportError:
+  numpy = None
+
+try:
+  import pandas  # pylint: disable=import-error
+except ImportError:
+  pandas = None
+
+
+def RequireModules():
+  if numpy is None or pandas is None:
+    sys.exit(
+        'ERROR: Some required python modules are not available.\n\n'
+        'Make sure to run this script using vpython or ensure that '
+        'module dependencies listed in src/.vpython are satisfied.')

tools/perf/flakiness_cli

@@ -6,8 +6,11 @@
 """This tool provides a command line interface for the flakiness dashboard."""
 
 import sys
+
+from core import external_modules
 from cli_tools import flakiness_cli
 
 
 if __name__ == '__main__':
+  external_modules.RequireModules()
   sys.exit(flakiness_cli.Main())