SERVER-29642 SERVER-29643 Add Python tests for test lifecycle scripts.

For test_failures.py:
  * Replaces HistoryReport with a TestHistory class that has
    get_history_by_revision() and get_history_by_date() methods. They
    both return a list of ReportEntry tuples that can be used to
    construct a Report instance.
  * Adds Python unit test cases for the Report and ReportEntry classes.
  * Creates Wildcard class as separate concept from Missing class.
  * Enables --sinceDate and --untilDate with a warning that the script
    may not return a complete result set.
  * Adds support for running the script with Python 3.

For update_test_lifecycle.py:
  * Introduces Config namedtuple to represent the test lifecycle model.
  * Adds Python unit tests cases for the update_tags() function.
  * Takes advantage of the partial grouping so that computing summaries
    for (test, task, variant), (test, task), and (test,) combinations do
    not require re-processing the entire result set.

1 files changed, 33 insertions, 6 deletions

diff --git a/buildscripts/ciconfig/tags.py b/buildscripts/ciconfig/tags.py
index dbd090bc9a8..dfab58832fa 100644
--- a/buildscripts/ciconfig/tags.py
+++ b/buildscripts/ciconfig/tags.py
@@ -1,4 +1,5 @@
 """Module to access and modify tag configuration files used by resmoke."""
+
 from __future__ import absolute_import
 from __future__ import print_function
 
@@ -11,7 +12,7 @@ import yaml
 
 # Setup to preserve order in yaml.dump, see https://stackoverflow.com/a/8661021
 def _represent_dict_order(self, data):
-    return self.represent_mapping('tag:yaml.org,2002:map', data.items())
+    return self.represent_mapping("tag:yaml.org,2002:map", data.items())
 
 yaml.add_representer(collections.OrderedDict, _represent_dict_order)
 # End setup
@@ -20,17 +21,38 @@ yaml.add_representer(collections.OrderedDict, _represent_dict_order)
 class TagsConfig(object):
     """Represent a test tag configuration file."""
 
-    def __init__(self, filename, cmp_func=None):
-        """Initialize a TagsConfig from a file.
+    def __init__(self, raw, cmp_func=None):
+        """Initialize a TagsConfig from a dict representing the associations between tests and tags.
 
         'cmp_func' can be used to specify a comparison function that will be used when sorting tags.
         """
-        with open(filename, "r") as fstream:
-            self.raw = yaml.safe_load(fstream)
+
+        self.raw = raw
         self._conf = self.raw["selector"]
         self._conf_copy = copy.deepcopy(self._conf)
         self._cmp_func = cmp_func
 
+    @classmethod
+    def from_file(cls, filename, **kwargs):
+        """Return a TagsConfig from a file containing the associations between tests and tags.
+
+        See TagsConfig.__init__() for the keyword arguments that can be specified.
+        """
+
+        with open(filename, "r") as fstream:
+            raw = yaml.safe_load(fstream)
+
+        return cls(raw, **kwargs)
+
+    @classmethod
+    def from_dict(cls, raw, **kwargs):
+        """Return a TagsConfig from a dict representing the associations between tests and tags.
+
+        See TagsConfig.__init__() for the keyword arguments that can be specified.
+        """
+
+        return cls(copy.deepcopy(raw), **kwargs)
+
     def get_test_kinds(self):
         """List the test kinds."""
         return self._conf.keys()
@@ -75,9 +97,14 @@ class TagsConfig(object):
         """
         with open(filename, "w") as fstream:
             if preamble:
-                print(textwrap.fill(preamble, width=100, initial_indent="# ",
+                print(textwrap.fill(preamble,
+                                    width=100,
+                                    initial_indent="# ",
                                     subsequent_indent="# "),
                       file=fstream)
+
+            # We use yaml.safe_dump() in order avoid having strings being written to the file as
+            # "!!python/unicode ..." and instead have them written as plain 'str' instances.
             yaml.safe_dump(self.raw, fstream, default_flow_style=False)