More debugging.

Author: nedbat

coverage/data.py

@@ -727,6 +727,8 @@ def combine_parallel_data(data, aliases=None, data_paths=None, strict=False):
 
     files_combined = 0
     for f in files_to_combine:
+        if data._debug and data._debug.should('dataio'):
+            data._debug.write("Combining data file %r" % (f,))
         try:
             new_data = CoverageData(f, debug=data._debug)
             new_data.read()

coverage/sqldata.py

@@ -167,6 +167,12 @@ def __nonzero__(self):
 
     __bool__ = __nonzero__
 
+    def dump(self):                                         # pragma: debugging
+        """Write a dump of the database."""
+        if self._debug:
+            with self._connect() as con:
+                self._debug.write(con.dump())
+
     def _file_id(self, filename, add=False):
         """Get the file id for `filename`.
 
@@ -519,3 +525,7 @@ def executemany(self, sql, data):
         if self.debug:
             self.debug.write("Executing many {!r} with {} rows".format(sql, len(data)))
         return self.con.executemany(sql, data)
+
+    def dump(self):                                         # pragma: debugging
+        """Return a multi-line string, the dump of the database."""
+        return "\n".join(self.con.iterdump())