htmlresult: Graceful disable it if pystache is not installed.

Test for features HTML_REPORT_CAPABLE and HTML_REPORT_SUPPORT to
graceful disable the htmlreport if pystache is not installed.
Signed-off-by: NRudá Moura <rmoura@redhat.com>

avocado/job.py

@@ -40,14 +40,9 @@ from avocado.plugins import jsonresult
 from avocado.plugins import xunit
 from avocado.utils import archive
 from avocado.utils import path
+from avocado.plugins import htmlresult
 
-
-try:
-    from avocado.plugins import htmlresult
-    HTML_REPORT_SUPPORT = True
-except ImportError:
-    HTML_REPORT_SUPPORT = False
-
+HTML_REPORT_SUPPORT = htmlresult.HTML_REPORT_CAPABLE
 _NEW_ISSUE_LINK = 'https://github.com/avocado-framework/avocado/issues/new'
 
 

avocado/plugins/htmlresult.py

@@ -21,7 +21,12 @@ import sys
 import time
 import webbrowser
 
-import pystache
+try:
+    import pystache
+except ImportError:
+    HTML_REPORT_CAPABLE = False
+else:
+    HTML_REPORT_CAPABLE = True
 
 from avocado import runtime
 from avocado.core import exit_codes
@@ -248,6 +253,9 @@ class HTML(plugin.Plugin):
     enabled = True
 
     def configure(self, parser):
+        if HTML_REPORT_CAPABLE is False:
+            self.enabled = False
+            return
         self.parser = parser
         self.parser.runner.add_argument(
             '--html', type=str,