plugins.diff: Allow to strip ids from test names

The test name combines $test_id-$test_name;$variant_id, which prevents
from comparing apples to oranges, but for some jobs we know the
$test_name itself identifies the test well enough and by stripping the
$test_id we can easily compare even tests with different number of
tests.

Example with ids (stock):

    -1-passtest.py:PassTest.test: PASS
    +1-failtest.py:FailTest.test: FAIL
    +2-passtest.py:PassTest.test: PASS

The same without ids (--diff-strip-id):

    +failtest.py:FailTest.test: FAIL
    passtest.py:PassTest.test: PASS

and it gets more useful with multiple inserted tests.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/plugins/diff.py

@@ -84,6 +84,10 @@ class Diff(CLICmd):
                             '(no)config,(no)sysinfo (defaults to all '
                             'enabled).')
 
+        parser.add_argument('--diff-strip-id', action='store_true',
+                            help="Strip the 'id' from 'id-name;variant' when "
+                            "comparing test results.")
+
         parser.add_argument('--paginator',
                             choices=('on', 'off'), default='on',
                             help='Turn the paginator on/off. '
@@ -97,6 +101,12 @@ class Diff(CLICmd):
                         'in the standard output.'
 
     def run(self, args):
+        def _get_name(test):
+            return str(test['id'])
+
+        def _get_name_no_id(test):
+            return str(test['id']).split('-', 1)[1]
+
         job1_dir, job1_id = self._setup_job(args.jobids[0])
         job2_dir, job2_id = self._setup_job(args.jobids[1])
 
@@ -145,13 +155,19 @@ class Diff(CLICmd):
 
         if 'results' in args.diff_filter:
             results1 = []
+            if args.diff_strip_id:
+                get_name = _get_name_no_id
+            else:
+                get_name = _get_name
             for test in job1_data['tests']:
-                test_result = '%s: %s\n' % (str(test['id']),
+                test_result = '%s: %s\n' % (get_name(test),
                                             str(test['status']))
+                if args.diff_strip_id:
+                    test
                 results1.append(test_result)
             results2 = []
             for test in job2_data['tests']:
-                test_result = '%s: %s\n' % (str(test['id']),
+                test_result = '%s: %s\n' % (get_name(test),
                                             str(test['status']))
                 results2.append(test_result)