bpo-44859: Raise more accurate exceptions in `sqlite3` (GH-27695)

* Improve exception compliance with PEP 249
* Raise InterfaceError instead of ProgrammingError for SQLITE_MISUSE.
  If SQLITE_MISUSE is raised, it is a sqlite3 module bug. Users of the
  sqlite3 module are not responsible for using the SQLite C API correctly.
* Don't overwrite BufferError with ValueError when conversion to BLOB fails.
* Raise ProgrammingError instead of Warning if user tries to execute() more
  than one SQL statement.
* Raise ProgrammingError instead of ValueError if an SQL query contains null characters.
* Make sure `_pysqlite_set_result` raises an exception if it returns -1.

1 files changed, 16 insertions, 1 deletions

diff --git a/Lib/test/test_sqlite3/test_userfunctions.py b/Lib/test/test_sqlite3/test_userfunctions.py
index 2588cae..9070c9e 100644
--- a/Lib/test/test_sqlite3/test_userfunctions.py
+++ b/Lib/test/test_sqlite3/test_userfunctions.py
@@ -196,6 +196,8 @@ class FunctionTests(unittest.TestCase):
         self.con.create_function("returnlonglong", 0, func_returnlonglong)
         self.con.create_function("returnnan", 0, lambda: float("nan"))
         self.con.create_function("returntoolargeint", 0, lambda: 1 << 65)
+        self.con.create_function("return_noncont_blob", 0,
+                                 lambda: memoryview(b"blob")[::2])
         self.con.create_function("raiseexception", 0, func_raiseexception)
         self.con.create_function("memoryerror", 0, func_memoryerror)
         self.con.create_function("overflowerror", 0, func_overflowerror)
@@ -340,10 +342,17 @@ class FunctionTests(unittest.TestCase):
                                "select spam(?)", (1 << 65,))
 
     def test_non_contiguous_blob(self):
-        self.assertRaisesRegex(ValueError, "could not convert BLOB to buffer",
+        self.assertRaisesRegex(BufferError,
+                               "underlying buffer is not C-contiguous",
                                self.con.execute, "select spam(?)",
                                (memoryview(b"blob")[::2],))
 
+    @with_tracebacks(BufferError, regex="buffer.*contiguous")
+    def test_return_non_contiguous_blob(self):
+        with self.assertRaises(sqlite.OperationalError):
+            cur = self.con.execute("select return_noncont_blob()")
+            cur.fetchone()
+
     def test_param_surrogates(self):
         self.assertRaisesRegex(UnicodeEncodeError, "surrogates not allowed",
                                self.con.execute, "select spam(?)",
@@ -466,6 +475,12 @@ class FunctionTests(unittest.TestCase):
             with self.assertRaises(sqlite.DataError):
                 cur.execute("select largeblob()")
 
+    def test_func_return_illegal_value(self):
+        self.con.create_function("badreturn", 0, lambda: self)
+        msg = "user-defined function raised exception"
+        self.assertRaisesRegex(sqlite.OperationalError, msg,
+                               self.con.execute, "select badreturn()")
+
 
 class AggregateTests(unittest.TestCase):
     def setUp(self):