pg-ext: fix initial client_encoding (#8151)

PR #7747 changed SQL settings to always be a tuple, and missed this one.

The added tests don't fail without this fix, because PostgreSQL is
actually happy with `'\"U\", \"T\", \"F\", \"-\", \"8\"'` as UTF-8; The
assertion in `setting_to_sql()` will fail without the fix.

edb/server/pgcon/pgcon.pyx

@@ -82,6 +82,7 @@ from edb.server import metrics
 from edb.server.protocol cimport frontend
 
 from edb.common import debug
+from edb.common import typeutils
 
 from . import errors as pgerror
 
@@ -3016,6 +3017,7 @@ cdef EdegDBCodecContext DEFAULT_CODEC_CONTEXT = EdegDBCodecContext()
 
 
 cdef setting_to_sql(setting):
+    assert typeutils.is_container(setting)
     return ', '.join(setting_val_to_sql(v) for v in setting)
 
 

edb/server/protocol/pg_ext.pyx

@@ -687,7 +687,7 @@ cdef class PgConnection(frontend.FrontendConnection):
                     f'invalid value for parameter "client_encoding": "{encoding}"',
                 )
             self._dbview._settings = self._dbview._settings.set(
-                "client_encoding", client_encoding
+                "client_encoding", (client_encoding,)
             )
         else:
             client_encoding = "UTF8"
@@ -1804,7 +1804,7 @@ cdef write_arg(
     elif pg_type == ('bool',):
         is_truthy = is_setting_truthy(value)
         if is_truthy == None:
-            buf.write_int32(-1)    
+            buf.write_int32(-1)
         else:
             buf.write_int32(1)
             buf.write_byte(1 if is_truthy else 0)

tests/test_sql_query.py

@@ -1591,21 +1591,43 @@ async def test_sql_query_be_state(self):
             await con.aclose()
 
     async def test_sql_query_client_encoding_1(self):
+        self.assertEqual(
+            self.scon.get_settings().client_encoding.lower(), "utf_8"
+        )
         rv1 = await self.squery_values('select * from "Genre" order by id')
         await self.squery_values("set client_encoding to 'GBK'")
         rv2 = await self.squery_values('select * from "Genre" order by id')
+        self.assertEqual(
+            self.scon.get_settings().client_encoding.lower(), "gbk"
+        )
         self.assertEqual(rv1, rv2)
 
     async def test_sql_query_client_encoding_2(self):
         await self.squery_values("set client_encoding to 'sql-ascii'")
+        self.assertEqual(
+            self.scon.get_settings().client_encoding.lower(), "sql_ascii"
+        )
         await self.squery_values('select * from "Movie"')
         with self.assertRaises(UnicodeDecodeError):
             await self.squery_values('select * from "Genre"')
 
         await self.squery_values("set client_encoding to 'latin1'")
+        self.assertEqual(
+            self.scon.get_settings().client_encoding.lower(), "latin1"
+        )
         with self.assertRaises(asyncpg.UntranslatableCharacterError):
             await self.squery_values('select * from "Genre"')
 
+    async def test_sql_query_client_encoding_3(self):
+        non_english = "奇奇怪怪"
+        rv1 = await self.squery_values('select $1::text', non_english)
+        await self.squery_values("set client_encoding to 'GBK'")
+        rv2 = await self.squery_values('select $1::text', non_english)
+        self.assertEqual(
+            self.scon.get_settings().client_encoding.lower(), "gbk"
+        )
+        self.assertEqual(rv1, rv2)
+
     async def test_sql_query_server_version(self):
         version = await self.scon.fetchval("show server_version")
         self.assertEqual(