Add a boolean interpretation of CoverageData.

2 files changed, 6 insertions, 2 deletions

diff --git a/coverage/control.py b/coverage/control.py
index ca3660a..7c14e1b 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -772,8 +772,7 @@ class Coverage(object):
                     )
 
         # Find out if we got any data.
-        summary = self.data.summary()
-        if not summary and self._warn_no_data:
+        if not self.data and self._warn_no_data:
             self._warn("No data was collected.")
 
         # Find files that were never executed at all.
diff --git a/coverage/data.py b/coverage/data.py
index 7b9dd7e..c9e9a03 100644
--- a/coverage/data.py
+++ b/coverage/data.py
@@ -230,6 +230,11 @@ class CoverageData(object):
             summ[filename_fn(filename)] = len(lines)
         return summ
 
+    def __nonzero__(self):
+        return bool(self._lines) or bool(self._arcs)
+
+    __bool__ = __nonzero__
+
     def has_arcs(self):
         """Does this data have arcs?"""
         return bool(self._arcs)