avocado: Change output plugins to have extra 'output' and 'output_option' attr

In order to be able to tell whether there's more than one
output plugin trying to use the stdout, add the 'output'
and 'output_option' attributes. This changes the current
output plugins to use and set these attributes correctly.

Fix the xunit unittest to take into account the new
attribute names.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/plugins/journal.py

@@ -86,6 +86,14 @@ class TestResultJournal(TestResult):
                                      status))
         self.journal.commit()
 
+    def set_output(self):
+        # Journal does not output to stdout
+        self.output = None
+
+    def set_output_option(self):
+        # Journal does not need an output option
+        self.output_option = None
+
     def start_test(self, test):
         # lazy init because we need the toplevel logdir for the job
         if not self.journal_initialized:

avocado/plugins/jsonresult.py

@@ -28,6 +28,12 @@ class JSONTestResult(TestResult):
     JSON Test Result class.
     """
 
+    def set_output(self):
+        self.output = getattr(self.args, 'json_output', '-')
+
+    def set_output_option(self):
+        self.output_option = '--json'
+
     def start_tests(self):
         """
         Called once before any tests are executed.

avocado/plugins/vm.py

@@ -168,6 +168,12 @@ class VMTestResult(TestResult):
         if self.args.vm_cleanup is True and self.vm.snapshot is not None:
             self.vm.restore_snapshot()
 
+    def set_output(self):
+        self.output = '-'
+
+    def set_output_option(self):
+        self.output_option = "--vm"
+
     def start_tests(self):
         """
         Called once before any tests are executed.

avocado/plugins/xunit.py

@@ -28,8 +28,9 @@ class XmlResult(object):
     Handles the XML details for xUnit output.
     """
 
-    def __init__(self):
+    def __init__(self, output):
         self.xml = ['<?xml version="1.0" encoding="UTF-8"?>']
+        self.output = output
 
     def _escape_attr(self, attrib):
         return quoteattr(attrib)
@@ -37,12 +38,14 @@ class XmlResult(object):
     def _escape_cdata(self, cdata):
         return cdata.replace(']]>', ']]>]]&gt;<![CDATA[')
 
-    def save(self, filename):
+    def save(self, filename=None):
         """
         Save the XML document to a file or standard output.
 
         :param filename: File name to save. Use '-' for standard output.
         """
+        if filename is None:
+            filename = self.output
         xml = '\n'.join(self.xml)
         if filename == '-':
             sys.stdout.write(xml)
@@ -158,8 +161,13 @@ class xUnitTestResult(TestResult):
         :param args: an instance of :class:`argparse.Namespace`.
         """
         TestResult.__init__(self, stream, args)
-        self.filename = getattr(self.args, 'xunit_output', '-')
-        self.xml = XmlResult()
+        self.xml = XmlResult(self.output)
+
+    def set_output(self):
+        self.output = getattr(self.args, 'xunit_output', '-')
+
+    def set_output_option(self):
+        self.output_option = '--xunit'
 
     def start_tests(self):
         """
@@ -199,7 +207,7 @@ class xUnitTestResult(TestResult):
                   'skip': len(self.skipped),
                   'total_time': self.total_time}
         self.xml.end_testsuite(**values)
-        self.xml.save(self.filename)
+        self.xml.save()
 
 
 class XUnit(plugin.Plugin):

avocado/result.py

@@ -108,6 +108,33 @@ class TestResult(object):
         self.failed = []
         self.skipped = []
         self.warned = []
+        # The convention is that a dash denotes stdout.
+        self.output = '-'
+        self.set_output()
+        self.output_option = None
+        self.set_output_option()
+
+    def set_output(self):
+        """
+        Set the value of the output attribute.
+
+        By default, output is the stream (stdout), denoted by '-'.
+
+        Must be implemented by plugins, so avocado knows where the plugin wants
+        to output to, avoiding clashes among different plugins that want to
+        use the stream at the same time.
+        """
+        pass
+
+    def set_output_option(self):
+        """
+        Set the value of the output option (command line).
+
+        Must be implemented by plugins, so avocado prints a friendly
+        message to users who are using more than one plugin to print results
+        to stdout.
+        """
+        pass
 
     def start_tests(self):
         """

selftests/all/unit/avocado/xunit_unittest.py

@@ -14,6 +14,7 @@
 # Copyright: Red Hat Inc. 2014
 # Author: Ruda Moura <rmoura@redhat.com>
 
+import argparse
 import unittest
 import os
 import sys
@@ -30,12 +31,17 @@ from avocado.plugins import xunit
 from avocado import test
 
 
+class ParseXMLError(Exception):
+    pass
+
+
 class xUnitSucceedTest(unittest.TestCase):
 
     def setUp(self):
         self.tmpfile = mkstemp()
-        self.test_result = xunit.xUnitTestResult()
-        self.test_result.filename = self.tmpfile[1]
+        args = argparse.Namespace()
+        args.xunit_output = self.tmpfile[1]
+        self.test_result = xunit.xUnitTestResult(args=args)
         self.test_result.start_tests()
         self.test1 = test.Test()
         self.test1.status = 'PASS'
@@ -50,9 +56,12 @@ class xUnitSucceedTest(unittest.TestCase):
         self.test_result.end_test(self.test1)
         self.test_result.end_tests()
         self.assertTrue(self.test_result.xml)
-        with open(self.test_result.filename) as fp:
+        with open(self.test_result.output) as fp:
             xml = fp.read()
-        dom = minidom.parseString(xml)
+        try:
+            dom = minidom.parseString(xml)
+        except Exception, details:
+            raise ParseXMLError("Error parsing XML: '%s'.\nXML Contents:\n%s" % (details, xml))
         self.assertTrue(dom)
         els = dom.getElementsByTagName('testcase')
         self.assertEqual(len(els), 1)