Add combine --keep (#1110)

* Add combine --keep

Related to https://github.com/nedbat/coveragepy/issues/1108

* Fix unit tests

* Fix line too long

* Fix line too long

1 files changed, 5 insertions, 2 deletions

diff --git a/coverage/control.py b/coverage/control.py
index 8d129bcb..c952afcd 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -659,7 +659,7 @@ class Coverage(object):
         data = self.get_data()
         data.write()
 
-    def combine(self, data_paths=None, strict=False):
+    def combine(self, data_paths=None, strict=False, keep=False):
         """Combine together a number of similarly-named coverage data files.
 
         All coverage data files whose name starts with `data_file` (from the
@@ -674,6 +674,8 @@ class Coverage(object):
         If `strict` is true, then it is an error to attempt to combine when
         there are no data files to combine.
 
+        If `keep` is true, then combined data files won't be deleted.
+
         .. versionadded:: 4.0
             The `data_paths` parameter.
 
@@ -694,7 +696,8 @@ class Coverage(object):
                 for pattern in paths[1:]:
                     aliases.add(pattern, result)
 
-        combine_parallel_data(self._data, aliases=aliases, data_paths=data_paths, strict=strict)
+        combine_parallel_data(self._data,
+                        aliases=aliases, data_paths=data_paths, strict=strict, keep=keep)
 
     def get_data(self):
         """Get the collected data.