From d9bc47d0db97ea47ebbe1b775947049792e8aa00 Mon Sep 17 00:00:00 2001
From: Ned Batchelder <ned@nedbatchelder.com>
Date: Tue, 3 Sep 2019 13:36:10 -0400
Subject: Updating with an empty data is ok

With no arc or line data, it used to choose lines arbitrarily, which
would fail if an empty data was updating an arc data.
---
 coverage/sqldata.py | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

(limited to 'coverage/sqldata.py')

diff --git a/coverage/sqldata.py b/coverage/sqldata.py
index babfcb8d..06ccff52 100644
--- a/coverage/sqldata.py
+++ b/coverage/sqldata.py
@@ -411,6 +411,8 @@ class CoverageData(SimpleReprMixin):
                 )
 
     def _choose_lines_or_arcs(self, lines=False, arcs=False):
+        assert lines or arcs
+        assert not (lines and arcs)
         if lines and self._has_arcs:
             raise CoverageException("Can't add lines to existing arc data")
         if arcs and self._has_lines:
@@ -480,6 +482,8 @@ class CoverageData(SimpleReprMixin):
         If `aliases` is provided, it's a `PathAliases` object that is used to
         re-map paths to match the local machine's.
         """
+        if self._debug.should('dataop'):
+            self._debug.write("Updating with data from %r" % (getattr(other_data, '_filename', '???'),))
         if self._has_lines and other_data._has_arcs:
             raise CoverageException("Can't combine arc data with line data")
         if self._has_arcs and other_data._has_lines:
@@ -608,23 +612,27 @@ class CoverageData(SimpleReprMixin):
                 lines[key] = numbits
             cur.close()
 
-            self._choose_lines_or_arcs(arcs=bool(arcs), lines=bool(lines))
+            if arcs:
+                self._choose_lines_or_arcs(arcs=True)
 
-            # Write the combined data.
-            conn.executemany(
-                'insert or ignore into arc '
-                '(file_id, context_id, fromno, tono) values (?, ?, ?, ?)',
-                arc_rows
-            )
-            conn.execute("delete from line_bits")
-            conn.executemany(
-                "insert into line_bits "
-                "(file_id, context_id, numbits) values (?, ?, ?)",
-                [
-                    (file_ids[file], context_ids[context], numbits)
-                    for (file, context), numbits in lines.items()
-                ]
-            )
+                # Write the combined data.
+                conn.executemany(
+                    'insert or ignore into arc '
+                    '(file_id, context_id, fromno, tono) values (?, ?, ?, ?)',
+                    arc_rows
+                )
+
+            if lines:
+                self._choose_lines_or_arcs(lines=True)
+                conn.execute("delete from line_bits")
+                conn.executemany(
+                    "insert into line_bits "
+                    "(file_id, context_id, numbits) values (?, ?, ?)",
+                    [
+                        (file_ids[file], context_ids[context], numbits)
+                        for (file, context), numbits in lines.items()
+                    ]
+                )
             conn.executemany(
                 'insert or ignore into tracer (file_id, tracer) values (?, ?)',
                 ((file_ids[filename], tracer) for filename, tracer in tracer_map.items())
-- 
cgit v1.2.1