Add docs for new tests

testing/test_junitxml.py

@@ -475,6 +475,7 @@ def test_logxml_changingdir(testdir):
     assert testdir.tmpdir.join("a/x.xml").check()
 
 def test_logxml_makedir(testdir):
+    """--junitxml should automatically create directories for the xml file"""
     testdir.makepyfile("""
         def test_pass():
             pass

testing/test_resultlog.py

@@ -181,6 +181,7 @@ def test_generic(testdir, LineMatcher):
     ])
 
 def test_makedir_for_resultlog(testdir, LineMatcher):
+    """--resultlog should automatically create directories for the log file"""
     testdir.plugins.append("resultlog")
     testdir.makepyfile("""
         import pytest