Start unit testing the arc measurement. In arcs, -1 means enter or exit.

1 files changed, 4 insertions, 0 deletions

diff --git a/coverage/data.py b/coverage/data.py
index 26dc5aa..0c1fc3a 100644
--- a/coverage/data.py
+++ b/coverage/data.py
@@ -198,6 +198,10 @@ class CoverageData:
         """
         return self.lines.get(filename) or {}
 
+    def executed_arcs(self, filename):
+        """A map containing all the arcs executed in `filename`."""
+        return self.arcs.get(filename) or {}
+
     def summary(self, fullpath=False):
         """Return a dict summarizing the coverage data.