Add unit tests for SystemTestsCompareTwo

Note that I needed to extract pieces of the SystemTestsCommon __init__ method
into their own methods so that I could stub them out for testing.

Test suite: None
Test baseline: N/A
Test namelist changes: N/A
Test status: N/A

Ran new unit tests with:

[roo2:~/cime/utils/python]$ python -m unittest discover

Note: This fails with python3 due to use of python2 print in compare_env_run

Fixes: None

User interface changes?: No

Code review: None

utils/python/CIME/SystemTests/system_tests_common.py

@@ -27,9 +27,24 @@ def __init__(self, case, expected=None):
         self._caseroot = caseroot
         self._orig_caseroot = caseroot
         self._runstatus = None
+
+        self._init_environment(caseroot)
+        self._init_locked_files(caseroot, expected)
+        self._init_case_setup()
+
+    def _init_environment(self, caseroot):
+        """
+        Do initializations of environment variables that are needed in __init__
+        """
         # Needed for sh scripts
         os.environ["CASEROOT"] = caseroot
 
+    def _init_locked_files(self, caseroot, expected):
+        """
+        If the file LockedFiles/env_run.orig.xml does not exist, copy the current
+        env_run.xml file. If it does exist, restore values changed in a previous
+        run of the test.
+        """
         if os.path.isfile(os.path.join(caseroot, "LockedFiles", "env_run.orig.xml")):
             self.compare_env_run(expected=expected)
         elif os.path.isfile(os.path.join(caseroot, "env_run.xml")):
@@ -41,6 +56,10 @@ def __init__(self, case, expected=None):
             shutil.copy(os.path.join(caseroot,"env_run.xml"),
                         os.path.join(lockedfiles, "env_run.orig.xml"))
 
+    def _init_case_setup(self):
+        """
+        Do initial case setup needed in __init__
+        """
         if self._case.get_value("IS_FIRST_RUN"):
             self._case.set_initial_test_values()
 

utils/python/CIME/SystemTests/system_tests_compare_two.py

@@ -143,6 +143,7 @@ def _pre_build(self):
 
     def build(self, sharedlib_only=False, model_only=False):
         self._pre_build()
+
         if self._needs_two_builds(sharedlib_only = sharedlib_only,
                                   model_only = model_only):
             raise NotImplementedError('Two builds not yet implemented')
@@ -154,6 +155,7 @@ def run(self):
         Runs both phases of the two-phase test and compares their results
         """
 
+        # First run
         self._run_common_setup()
         self._run_one_setup()
         logger.info('Doing first run: ' + self._run_one_description)
@@ -164,6 +166,7 @@ def run(self):
             self._status_run1 = "FAIL"
             return False
 
+        # Second run
         self._run_common_setup()
         self._run_two_setup()
         logger.info('Doing second run: ' + self._run_two_description)
@@ -174,6 +177,7 @@ def run(self):
             self._status_run2 = "FAIL"
             return False
 
+        # Compare results
         success = self._component_compare_test(self._run_one_suffix, self._run_two_suffix)
         if success:
             self._status_compare = "PASS"
@@ -183,6 +187,25 @@ def run(self):
 
         return success
 
+    def get_run_one_status(self):
+        """
+        Returns a string specifying the status of run 1
+        """
+        return self._status_run1
+
+    def get_run_two_status(self):
+        """
+        Returns a string specifying the status of run 2
+        """
+        return self._status_run2
+
+    def get_compare_status(self):
+        """
+        Returns a string specifying the status of the comparison between run 1
+        and run 2
+        """
+        return self._status_compare
+
     # ========================================================================
     # Private methods
     # ========================================================================