Update dialect for pg8000 version 1.16.0

The pg8000 dialect has been revised and modernized for the most recent
version of the pg8000 driver for PostgreSQL.  Changes to the dialect
include:

* All data types are now sent as text rather than binary.

* Using adapters, custom types can be plugged in to pg8000.

* Previously, named prepared statements were used for all statements.
  Now unnamed prepared statements are used by default, and named
  prepared statements can be used explicitly by calling the
  Connection.prepare() method, which returns a PreparedStatement
  object.

Pull request courtesy Tony Locke.

Notes by Mike: to get this all working it was needed to break
up JSONIndexType into "str" and "int" subtypes; this will be
needed for any dialect that is dependent on setinputsizes().

also includes @caselit's idea to include query params
in the dbdriver parameter.

Co-authored-by: Mike Bayer <mike_mp@zzzcomputing.com>

Closes: #5451
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5451
Pull-request-sha: 639751ca9c7544801b9ede02e6cbe15a16c59c82

Change-Id: I2869bc52c330916773a41d11d12c297aecc8fcd8

3 files changed, 22 insertions, 40 deletions

diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index fe74be823..f9fabbeed 100644
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -346,12 +346,12 @@ def _expect_raises(except_cls, msg=None, check_context=False):
     assert success, "Callable did not raise an exception"
 
 
-def expect_raises(except_cls):
-    return _expect_raises(except_cls, check_context=True)
+def expect_raises(except_cls, check_context=True):
+    return _expect_raises(except_cls, check_context=check_context)
 
 
-def expect_raises_message(except_cls, msg):
-    return _expect_raises(except_cls, msg=msg, check_context=True)
+def expect_raises_message(except_cls, msg, check_context=True):
+    return _expect_raises(except_cls, msg=msg, check_context=check_context)
 
 
 class AssertsCompiledSQL(object):
diff --git a/lib/sqlalchemy/testing/provision.py b/lib/sqlalchemy/testing/provision.py
index 21bacfca2..094d1ea94 100644
--- a/lib/sqlalchemy/testing/provision.py
+++ b/lib/sqlalchemy/testing/provision.py
@@ -7,6 +7,7 @@ from . import engines
 from .. import exc
 from ..engine import url as sa_url
 from ..util import compat
+from ..util import parse_qsl
 
 log = logging.getLogger(__name__)
 
@@ -85,7 +86,7 @@ def generate_db_urls(db_urls, extra_drivers):
         --dburi postgresql://db1  \
         --dburi postgresql://db2  \
         --dburi postgresql://db2  \
-        --dbdriver=psycopg2 --dbdriver=asyncpg
+        --dbdriver=psycopg2 --dbdriver=asyncpg?async_fallback=true
 
     Noting that the default postgresql driver is psycopg2.  the output
     would be::
@@ -139,21 +140,34 @@ def _generate_driver_urls(url, extra_drivers):
     main_driver = url.get_driver_name()
     extra_drivers.discard(main_driver)
 
-    url = generate_driver_url(url, main_driver)
+    url = generate_driver_url(url, main_driver, {})
     yield str(url)
 
     for drv in list(extra_drivers):
-        new_url = generate_driver_url(url, drv)
+
+        if "?" in drv:
+
+            driver_only, query_str = drv.split("?", 1)
+
+            query = parse_qsl(query_str)
+        else:
+            driver_only = drv
+            query = {}
+
+        new_url = generate_driver_url(url, driver_only, query)
         if new_url:
             extra_drivers.remove(drv)
+
             yield str(new_url)
 
 
 @register.init
-def generate_driver_url(url, driver):
+def generate_driver_url(url, driver, query):
     backend = url.get_backend_name()
     new_url = copy.copy(url)
+    new_url.query = dict(new_url.query)
     new_url.drivername = "%s+%s" % (backend, driver)
+    new_url.query.update(query)
     try:
         new_url.get_dialect()
     except exc.NoSuchModuleError:
diff --git a/lib/sqlalchemy/testing/suite/test_types.py b/lib/sqlalchemy/testing/suite/test_types.py
index 5e6ac1eab..6a390231b 100644
--- a/lib/sqlalchemy/testing/suite/test_types.py
+++ b/lib/sqlalchemy/testing/suite/test_types.py
@@ -34,7 +34,6 @@ from ... import testing
 from ... import Text
 from ... import Time
 from ... import TIMESTAMP
-from ... import type_coerce
 from ... import TypeDecorator
 from ... import Unicode
 from ... import UnicodeText
@@ -1161,37 +1160,6 @@ class JSONStringCastIndexTest(_LiteralRoundTripFixture, fixtures.TablesTest):
             and_(name == "r6", cast(col["b"], String) == '"some value"'), "r6"
         )
 
-    def test_crit_against_int_basic(self):
-        name = self.tables.data_table.c.name
-        col = self.tables.data_table.c["data"]
-
-        self._test_index_criteria(
-            and_(name == "r6", cast(col["a"], String) == "5"), "r6"
-        )
-
-    def _dont_test_crit_against_string_coerce_type(self):
-        name = self.tables.data_table.c.name
-        col = self.tables.data_table.c["data"]
-
-        self._test_index_criteria(
-            and_(
-                name == "r6",
-                cast(col["b"], String) == type_coerce("some value", JSON),
-            ),
-            "r6",
-            test_literal=False,
-        )
-
-    def _dont_test_crit_against_int_coerce_type(self):
-        name = self.tables.data_table.c.name
-        col = self.tables.data_table.c["data"]
-
-        self._test_index_criteria(
-            and_(name == "r6", cast(col["a"], String) == type_coerce(5, JSON)),
-            "r6",
-            test_literal=False,
-        )
-
 
 __all__ = (
     "UnicodeVarcharTest",