fix: raise CoverageException for SQLite connection errors

Author: nedbat

coverage/sqldata.py

@@ -1032,7 +1032,11 @@ def _connect(self):
         # is not a problem.
         if self.debug:
             self.debug.write(f"Connecting to {self.filename!r}")
-        self.con = sqlite3.connect(self.filename, check_same_thread=False)
+        try:
+            self.con = sqlite3.connect(self.filename, check_same_thread=False)
+        except sqlite3.Error as exc:
+            raise CoverageException(f"Couldn't use data file {self.filename!r}: {exc}") from exc
+
         self.con.create_function("REGEXP", 2, _regexp)
 
         # This pragma makes writing faster. It disables rollbacks, but we never need them.

tests/test_data.py

@@ -598,6 +598,14 @@ def test_read_errors(self):
             covdata.read()
         assert not covdata
 
+    def test_hard_read_error(self):
+        self.make_file("noperms.dat", "go away")
+        os.chmod("noperms.dat", 0)
+        msg = r"Couldn't .* '.*[/\\]{}': \S+"
+        with pytest.raises(CoverageException, match=msg.format("noperms.dat")):
+            covdata = DebugCoverageData("noperms.dat")
+            covdata.read()
+
     def test_read_sql_errors(self):
         with sqlite3.connect("wrong_schema.db") as con:
             con.execute("create table coverage_schema (version integer)")