test: cover the last edge cases in sqldata.py

Author: nedbat

coverage/sqldata.py

@@ -1068,7 +1068,7 @@ def __exit__(self, exc_type, exc_value, traceback):
             except Exception as exc:
                 if self.debug:
                     self.debug.write(f"EXCEPTION from __exit__: {exc}")
-                raise
+                raise CoverageException(f"Couldn't end data file {self.filename!r}: {exc}") from exc
 
     def execute(self, sql, parameters=()):
         """Same as :meth:`python:sqlite3.Connection.execute`."""
@@ -1095,7 +1095,7 @@ def execute(self, sql, parameters=()):
                             "Looks like a coverage 4.x data file. " +
                             "Are you mixing versions of coverage?"
                         )
-            except Exception:
+            except Exception:   # pragma: cant happen
                 pass
             if self.debug:
                 self.debug.write(f"EXCEPTION from execute: {msg}")
@@ -1116,7 +1116,7 @@ def execute_one(self, sql, parameters=()):
         elif len(rows) == 1:
             return rows[0]
         else:
-            raise CoverageException(f"Sql {sql!r} shouldn't return {len(rows)} rows")
+            raise AssertionError(f"SQL {sql!r} shouldn't return {len(rows)} rows")
 
     def executemany(self, sql, data):
         """Same as :meth:`python:sqlite3.Connection.executemany`."""
@@ -1125,7 +1125,7 @@ def executemany(self, sql, data):
             self.debug.write(f"Executing many {sql!r} with {len(data)} rows")
         try:
             return self.con.executemany(sql, data)
-        except Exception:
+        except Exception:   # pragma: cant happen
             # In some cases, an error might happen that isn't really an
             # error.  Try again immediately.
             # https://github.com/nedbat/coveragepy/issues/1010

tests/test_data.py

@@ -601,11 +601,21 @@ def test_read_errors(self):
     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")):
+        with pytest.raises(CoverageException, match=r"Couldn't .* '.*[/\\]noperms.dat': "):
             covdata = DebugCoverageData("noperms.dat")
             covdata.read()
 
+    @pytest.mark.parametrize("klass", [CoverageData, DebugCoverageData])
+    def test_error_when_closing(self, klass):
+        msg = r"Couldn't .* '.*[/\\]flaked.dat': \S+"
+        with pytest.raises(CoverageException, match=msg):
+            covdata = klass("flaked.dat")
+            covdata.add_lines(LINES_1)
+            # I don't know how to make a real error, so let's fake one.
+            sqldb = list(covdata._dbs.values())[0]
+            sqldb.close = lambda: 1/0
+            covdata.add_lines(LINES_1)
+
     def test_read_sql_errors(self):
         with sqlite3.connect("wrong_schema.db") as con:
             con.execute("create table coverage_schema (version integer)")