From 1dac2263372df2b85db5d029a45721fa158a5c9d Mon Sep 17 00:00:00 2001
From: xiubuzhe <xiubuzhe@sina.com>
Date: Sun, 8 Oct 2023 20:59:00 +0800
Subject: first add files

---
 lib/sqlalchemy/testing/requirements.py | 1518 ++++++++++++++++++++++++++++++++
 1 file changed, 1518 insertions(+)
 create mode 100644 lib/sqlalchemy/testing/requirements.py

(limited to 'lib/sqlalchemy/testing/requirements.py')

diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
new file mode 100644
index 0000000..857d1fd
--- /dev/null
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -0,0 +1,1518 @@
+# testing/requirements.py
+# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+
+"""Global database feature support policy.
+
+Provides decorators to mark tests requiring specific feature support from the
+target database.
+
+External dialect test suites should subclass SuiteRequirements
+to provide specific inclusion/exclusions.
+
+"""
+
+import platform
+import sys
+
+from . import exclusions
+from . import only_on
+from .. import util
+from ..pool import QueuePool
+
+
+class Requirements(object):
+    pass
+
+
+class SuiteRequirements(Requirements):
+    @property
+    def create_table(self):
+        """target platform can emit basic CreateTable DDL."""
+
+        return exclusions.open()
+
+    @property
+    def drop_table(self):
+        """target platform can emit basic DropTable DDL."""
+
+        return exclusions.open()
+
+    @property
+    def table_ddl_if_exists(self):
+        """target platform supports IF NOT EXISTS / IF EXISTS for tables."""
+
+        return exclusions.closed()
+
+    @property
+    def index_ddl_if_exists(self):
+        """target platform supports IF NOT EXISTS / IF EXISTS for indexes."""
+
+        return exclusions.closed()
+
+    @property
+    def foreign_keys(self):
+        """Target database must support foreign keys."""
+
+        return exclusions.open()
+
+    @property
+    def table_value_constructor(self):
+        """Database / dialect supports a query like::
+
+             SELECT * FROM VALUES ( (c1, c2), (c1, c2), ...)
+             AS some_table(col1, col2)
+
+        SQLAlchemy generates this with the :func:`_sql.values` function.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def standard_cursor_sql(self):
+        """Target database passes SQL-92 style statements to cursor.execute()
+        when a statement like select() or insert() is run.
+
+        A very small portion of dialect-level tests will ensure that certain
+        conditions are present in SQL strings, and these tests use very basic
+        SQL that will work on any SQL-like platform in order to assert results.
+
+        It's normally a given for any pep-249 DBAPI that a statement like
+        "SELECT id, name FROM table WHERE some_table.id=5" will work.
+        However, there are dialects that don't actually produce SQL Strings
+        and instead may work with symbolic objects instead, or dialects that
+        aren't working with SQL, so for those this requirement can be marked
+        as excluded.
+
+        """
+
+        return exclusions.open()
+
+    @property
+    def on_update_cascade(self):
+        """target database must support ON UPDATE..CASCADE behavior in
+        foreign keys."""
+
+        return exclusions.open()
+
+    @property
+    def non_updating_cascade(self):
+        """target database must *not* support ON UPDATE..CASCADE behavior in
+        foreign keys."""
+        return exclusions.closed()
+
+    @property
+    def deferrable_fks(self):
+        return exclusions.closed()
+
+    @property
+    def on_update_or_deferrable_fks(self):
+        # TODO: exclusions should be composable,
+        # somehow only_if([x, y]) isn't working here, negation/conjunctions
+        # getting confused.
+        return exclusions.only_if(
+            lambda: self.on_update_cascade.enabled
+            or self.deferrable_fks.enabled
+        )
+
+    @property
+    def queue_pool(self):
+        """target database is using QueuePool"""
+
+        def go(config):
+            return isinstance(config.db.pool, QueuePool)
+
+        return exclusions.only_if(go)
+
+    @property
+    def self_referential_foreign_keys(self):
+        """Target database must support self-referential foreign keys."""
+
+        return exclusions.open()
+
+    @property
+    def foreign_key_ddl(self):
+        """Target database must support the DDL phrases for FOREIGN KEY."""
+
+        return exclusions.open()
+
+    @property
+    def named_constraints(self):
+        """target database must support names for constraints."""
+
+        return exclusions.open()
+
+    @property
+    def implicitly_named_constraints(self):
+        """target database must apply names to unnamed constraints."""
+
+        return exclusions.open()
+
+    @property
+    def subqueries(self):
+        """Target database must support subqueries."""
+
+        return exclusions.open()
+
+    @property
+    def offset(self):
+        """target database can render OFFSET, or an equivalent, in a
+        SELECT.
+        """
+
+        return exclusions.open()
+
+    @property
+    def bound_limit_offset(self):
+        """target database can render LIMIT and/or OFFSET using a bound
+        parameter
+        """
+
+        return exclusions.open()
+
+    @property
+    def sql_expression_limit_offset(self):
+        """target database can render LIMIT and/or OFFSET with a complete
+        SQL expression, such as one that uses the addition operator.
+        parameter
+        """
+
+        return exclusions.open()
+
+    @property
+    def parens_in_union_contained_select_w_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when LIMIT/OFFSET is specifically present.
+
+        E.g. (SELECT ...) UNION (SELECT ..)
+
+        This is known to fail on SQLite.
+
+        """
+        return exclusions.open()
+
+    @property
+    def parens_in_union_contained_select_wo_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when OFFSET/LIMIT is specifically not present.
+
+        E.g. (SELECT ... LIMIT ..) UNION (SELECT .. OFFSET ..)
+
+        This is known to fail on SQLite.  It also fails on Oracle
+        because without LIMIT/OFFSET, there is currently no step that
+        creates an additional subquery.
+
+        """
+        return exclusions.open()
+
+    @property
+    def boolean_col_expressions(self):
+        """Target database must support boolean expressions as columns"""
+
+        return exclusions.closed()
+
+    @property
+    def nullable_booleans(self):
+        """Target database allows boolean columns to store NULL."""
+
+        return exclusions.open()
+
+    @property
+    def nullsordering(self):
+        """Target backends that support nulls ordering."""
+
+        return exclusions.closed()
+
+    @property
+    def standalone_binds(self):
+        """target database/driver supports bound parameters as column
+        expressions without being in the context of a typed column.
+        """
+        return exclusions.closed()
+
+    @property
+    def standalone_null_binds_whereclause(self):
+        """target database/driver supports bound parameters with NULL in the
+        WHERE clause, in situations where it has to be typed.
+
+        """
+        return exclusions.open()
+
+    @property
+    def intersect(self):
+        """Target database must support INTERSECT or equivalent."""
+        return exclusions.closed()
+
+    @property
+    def except_(self):
+        """Target database must support EXCEPT or equivalent (i.e. MINUS)."""
+        return exclusions.closed()
+
+    @property
+    def window_functions(self):
+        """Target database must support window functions."""
+        return exclusions.closed()
+
+    @property
+    def ctes(self):
+        """Target database supports CTEs"""
+
+        return exclusions.closed()
+
+    @property
+    def ctes_with_update_delete(self):
+        """target database supports CTES that ride on top of a normal UPDATE
+        or DELETE statement which refers to the CTE in a correlated subquery.
+
+        """
+
+        return exclusions.closed()
+
+    @property
+    def ctes_on_dml(self):
+        """target database supports CTES which consist of INSERT, UPDATE
+        or DELETE *within* the CTE, e.g. WITH x AS (UPDATE....)"""
+
+        return exclusions.closed()
+
+    @property
+    def autoincrement_insert(self):
+        """target platform generates new surrogate integer primary key values
+        when insert() is executed, excluding the pk column."""
+
+        return exclusions.open()
+
+    @property
+    def fetch_rows_post_commit(self):
+        """target platform will allow cursor.fetchone() to proceed after a
+        COMMIT.
+
+        Typically this refers to an INSERT statement with RETURNING which
+        is invoked within "autocommit".   If the row can be returned
+        after the autocommit, then this rule can be open.
+
+        """
+
+        return exclusions.open()
+
+    @property
+    def group_by_complex_expression(self):
+        """target platform supports SQL expressions in GROUP BY
+
+        e.g.
+
+        SELECT x + y AS somelabel FROM table GROUP BY x + y
+
+        """
+
+        return exclusions.open()
+
+    @property
+    def sane_rowcount(self):
+        return exclusions.skip_if(
+            lambda config: not config.db.dialect.supports_sane_rowcount,
+            "driver doesn't support 'sane' rowcount",
+        )
+
+    @property
+    def sane_multi_rowcount(self):
+        return exclusions.fails_if(
+            lambda config: not config.db.dialect.supports_sane_multi_rowcount,
+            "driver %(driver)s %(doesnt_support)s 'sane' multi row count",
+        )
+
+    @property
+    def sane_rowcount_w_returning(self):
+        return exclusions.fails_if(
+            lambda config: not (
+                config.db.dialect.supports_sane_rowcount_returning
+            ),
+            "driver doesn't support 'sane' rowcount when returning is on",
+        )
+
+    @property
+    def empty_inserts(self):
+        """target platform supports INSERT with no values, i.e.
+        INSERT DEFAULT VALUES or equivalent."""
+
+        return exclusions.only_if(
+            lambda config: config.db.dialect.supports_empty_insert
+            or config.db.dialect.supports_default_values
+            or config.db.dialect.supports_default_metavalue,
+            "empty inserts not supported",
+        )
+
+    @property
+    def empty_inserts_executemany(self):
+        """target platform supports INSERT with no values, i.e.
+        INSERT DEFAULT VALUES or equivalent, within executemany()"""
+
+        return self.empty_inserts
+
+    @property
+    def insert_from_select(self):
+        """target platform supports INSERT from a SELECT."""
+
+        return exclusions.open()
+
+    @property
+    def full_returning(self):
+        """target platform supports RETURNING completely, including
+        multiple rows returned.
+
+        """
+
+        return exclusions.only_if(
+            lambda config: config.db.dialect.full_returning,
+            "%(database)s %(does_support)s 'RETURNING of multiple rows'",
+        )
+
+    @property
+    def insert_executemany_returning(self):
+        """target platform supports RETURNING when INSERT is used with
+        executemany(), e.g. multiple parameter sets, indicating
+        as many rows come back as do parameter sets were passed.
+
+        """
+
+        return exclusions.only_if(
+            lambda config: config.db.dialect.insert_executemany_returning,
+            "%(database)s %(does_support)s 'RETURNING of "
+            "multiple rows with INSERT executemany'",
+        )
+
+    @property
+    def returning(self):
+        """target platform supports RETURNING for at least one row.
+
+        .. seealso::
+
+            :attr:`.Requirements.full_returning`
+
+        """
+
+        return exclusions.only_if(
+            lambda config: config.db.dialect.implicit_returning,
+            "%(database)s %(does_support)s 'RETURNING of a single row'",
+        )
+
+    @property
+    def tuple_in(self):
+        """Target platform supports the syntax
+        "(x, y) IN ((x1, y1), (x2, y2), ...)"
+        """
+
+        return exclusions.closed()
+
+    @property
+    def tuple_in_w_empty(self):
+        """Target platform tuple IN w/ empty set"""
+        return self.tuple_in
+
+    @property
+    def duplicate_names_in_cursor_description(self):
+        """target platform supports a SELECT statement that has
+        the same name repeated more than once in the columns list."""
+
+        return exclusions.open()
+
+    @property
+    def denormalized_names(self):
+        """Target database must have 'denormalized', i.e.
+        UPPERCASE as case insensitive names."""
+
+        return exclusions.skip_if(
+            lambda config: not config.db.dialect.requires_name_normalize,
+            "Backend does not require denormalized names.",
+        )
+
+    @property
+    def multivalues_inserts(self):
+        """target database must support multiple VALUES clauses in an
+        INSERT statement."""
+
+        return exclusions.skip_if(
+            lambda config: not config.db.dialect.supports_multivalues_insert,
+            "Backend does not support multirow inserts.",
+        )
+
+    @property
+    def implements_get_lastrowid(self):
+        """target dialect implements the executioncontext.get_lastrowid()
+        method without reliance on RETURNING.
+
+        """
+        return exclusions.open()
+
+    @property
+    def emulated_lastrowid(self):
+        """target dialect retrieves cursor.lastrowid, or fetches
+        from a database-side function after an insert() construct executes,
+        within the get_lastrowid() method.
+
+        Only dialects that "pre-execute", or need RETURNING to get last
+        inserted id, would return closed/fail/skip for this.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def emulated_lastrowid_even_with_sequences(self):
+        """target dialect retrieves cursor.lastrowid or an equivalent
+        after an insert() construct executes, even if the table has a
+        Sequence on it.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def dbapi_lastrowid(self):
+        """target platform includes a 'lastrowid' accessor on the DBAPI
+        cursor object.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def views(self):
+        """Target database must support VIEWs."""
+
+        return exclusions.closed()
+
+    @property
+    def schemas(self):
+        """Target database must support external schemas, and have one
+        named 'test_schema'."""
+
+        return only_on(lambda config: config.db.dialect.supports_schemas)
+
+    @property
+    def cross_schema_fk_reflection(self):
+        """target system must support reflection of inter-schema
+        foreign keys"""
+        return exclusions.closed()
+
+    @property
+    def foreign_key_constraint_name_reflection(self):
+        """Target supports refleciton of FOREIGN KEY constraints and
+        will return the name of the constraint that was used in the
+        "CONSTRAINT <name> FOREIGN KEY" DDL.
+
+        MySQL prior to version 8 and MariaDB prior to version 10.5
+        don't support this.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def implicit_default_schema(self):
+        """target system has a strong concept of 'default' schema that can
+        be referred to implicitly.
+
+        basically, PostgreSQL.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def default_schema_name_switch(self):
+        """target dialect implements provisioning module including
+        set_default_schema_on_connection"""
+
+        return exclusions.closed()
+
+    @property
+    def server_side_cursors(self):
+        """Target dialect must support server side cursors."""
+
+        return exclusions.only_if(
+            [lambda config: config.db.dialect.supports_server_side_cursors],
+            "no server side cursors support",
+        )
+
+    @property
+    def sequences(self):
+        """Target database must support SEQUENCEs."""
+
+        return exclusions.only_if(
+            [lambda config: config.db.dialect.supports_sequences],
+            "no sequence support",
+        )
+
+    @property
+    def no_sequences(self):
+        """the opposite of "sequences", DB does not support sequences at
+        all."""
+
+        return exclusions.NotPredicate(self.sequences)
+
+    @property
+    def sequences_optional(self):
+        """Target database supports sequences, but also optionally
+        as a means of generating new PK values."""
+
+        return exclusions.only_if(
+            [
+                lambda config: config.db.dialect.supports_sequences
+                and config.db.dialect.sequences_optional
+            ],
+            "no sequence support, or sequences not optional",
+        )
+
+    @property
+    def supports_lastrowid(self):
+        """target database / driver supports cursor.lastrowid as a means
+        of retrieving the last inserted primary key value.
+
+        note that if the target DB supports sequences also, this is still
+        assumed to work.  This is a new use case brought on by MariaDB 10.3.
+
+        """
+        return exclusions.only_if(
+            [lambda config: config.db.dialect.postfetch_lastrowid]
+        )
+
+    @property
+    def no_lastrowid_support(self):
+        """the opposite of supports_lastrowid"""
+        return exclusions.only_if(
+            [lambda config: not config.db.dialect.postfetch_lastrowid]
+        )
+
+    @property
+    def reflects_pk_names(self):
+        return exclusions.closed()
+
+    @property
+    def table_reflection(self):
+        """target database has general support for table reflection"""
+        return exclusions.open()
+
+    @property
+    def reflect_tables_no_columns(self):
+        """target database supports creation and reflection of tables with no
+        columns, or at least tables that seem to have no columns."""
+
+        return exclusions.closed()
+
+    @property
+    def comment_reflection(self):
+        return exclusions.closed()
+
+    @property
+    def view_column_reflection(self):
+        """target database must support retrieval of the columns in a view,
+        similarly to how a table is inspected.
+
+        This does not include the full CREATE VIEW definition.
+
+        """
+        return self.views
+
+    @property
+    def view_reflection(self):
+        """target database must support inspection of the full CREATE VIEW
+        definition."""
+        return self.views
+
+    @property
+    def schema_reflection(self):
+        return self.schemas
+
+    @property
+    def primary_key_constraint_reflection(self):
+        return exclusions.open()
+
+    @property
+    def foreign_key_constraint_reflection(self):
+        return exclusions.open()
+
+    @property
+    def foreign_key_constraint_option_reflection_ondelete(self):
+        return exclusions.closed()
+
+    @property
+    def fk_constraint_option_reflection_ondelete_restrict(self):
+        return exclusions.closed()
+
+    @property
+    def fk_constraint_option_reflection_ondelete_noaction(self):
+        return exclusions.closed()
+
+    @property
+    def foreign_key_constraint_option_reflection_onupdate(self):
+        return exclusions.closed()
+
+    @property
+    def fk_constraint_option_reflection_onupdate_restrict(self):
+        return exclusions.closed()
+
+    @property
+    def temp_table_reflection(self):
+        return exclusions.open()
+
+    @property
+    def temp_table_reflect_indexes(self):
+        return self.temp_table_reflection
+
+    @property
+    def temp_table_names(self):
+        """target dialect supports listing of temporary table names"""
+        return exclusions.closed()
+
+    @property
+    def temporary_tables(self):
+        """target database supports temporary tables"""
+        return exclusions.open()
+
+    @property
+    def temporary_views(self):
+        """target database supports temporary views"""
+        return exclusions.closed()
+
+    @property
+    def index_reflection(self):
+        return exclusions.open()
+
+    @property
+    def index_reflects_included_columns(self):
+        return exclusions.closed()
+
+    @property
+    def indexes_with_ascdesc(self):
+        """target database supports CREATE INDEX with per-column ASC/DESC."""
+        return exclusions.open()
+
+    @property
+    def indexes_with_expressions(self):
+        """target database supports CREATE INDEX against SQL expressions."""
+        return exclusions.closed()
+
+    @property
+    def unique_constraint_reflection(self):
+        """target dialect supports reflection of unique constraints"""
+        return exclusions.open()
+
+    @property
+    def check_constraint_reflection(self):
+        """target dialect supports reflection of check constraints"""
+        return exclusions.closed()
+
+    @property
+    def duplicate_key_raises_integrity_error(self):
+        """target dialect raises IntegrityError when reporting an INSERT
+        with a primary key violation.  (hint: it should)
+
+        """
+        return exclusions.open()
+
+    @property
+    def unbounded_varchar(self):
+        """Target database must support VARCHAR with no length"""
+
+        return exclusions.open()
+
+    @property
+    def unicode_data(self):
+        """Target database/dialect must support Python unicode objects with
+        non-ASCII characters represented, delivered as bound parameters
+        as well as in result rows.
+
+        """
+        return exclusions.open()
+
+    @property
+    def unicode_ddl(self):
+        """Target driver must support some degree of non-ascii symbol
+        names.
+        """
+        return exclusions.closed()
+
+    @property
+    def symbol_names_w_double_quote(self):
+        """Target driver can create tables with a name like 'some " table'"""
+        return exclusions.open()
+
+    @property
+    def datetime_literals(self):
+        """target dialect supports rendering of a date, time, or datetime as a
+        literal string, e.g. via the TypeEngine.literal_processor() method.
+
+        """
+
+        return exclusions.closed()
+
+    @property
+    def datetime(self):
+        """target dialect supports representation of Python
+        datetime.datetime() objects."""
+
+        return exclusions.open()
+
+    @property
+    def datetime_timezone(self):
+        """target dialect supports representation of Python
+        datetime.datetime() with tzinfo with DateTime(timezone=True)."""
+
+        return exclusions.closed()
+
+    @property
+    def time_timezone(self):
+        """target dialect supports representation of Python
+        datetime.time() with tzinfo with Time(timezone=True)."""
+
+        return exclusions.closed()
+
+    @property
+    def datetime_implicit_bound(self):
+        """target dialect when given a datetime object will bind it such
+        that the database server knows the object is a datetime, and not
+        a plain string.
+
+        """
+        return exclusions.open()
+
+    @property
+    def datetime_microseconds(self):
+        """target dialect supports representation of Python
+        datetime.datetime() with microsecond objects."""
+
+        return exclusions.open()
+
+    @property
+    def timestamp_microseconds(self):
+        """target dialect supports representation of Python
+        datetime.datetime() with microsecond objects but only
+        if TIMESTAMP is used."""
+        return exclusions.closed()
+
+    @property
+    def timestamp_microseconds_implicit_bound(self):
+        """target dialect when given a datetime object which also includes
+        a microseconds portion when using the TIMESTAMP data type
+        will bind it such that the database server knows
+        the object is a datetime with microseconds, and not a plain string.
+
+        """
+        return self.timestamp_microseconds
+
+    @property
+    def datetime_historic(self):
+        """target dialect supports representation of Python
+        datetime.datetime() objects with historic (pre 1970) values."""
+
+        return exclusions.closed()
+
+    @property
+    def date(self):
+        """target dialect supports representation of Python
+        datetime.date() objects."""
+
+        return exclusions.open()
+
+    @property
+    def date_coerces_from_datetime(self):
+        """target dialect accepts a datetime object as the target
+        of a date column."""
+
+        return exclusions.open()
+
+    @property
+    def date_historic(self):
+        """target dialect supports representation of Python
+        datetime.datetime() objects with historic (pre 1970) values."""
+
+        return exclusions.closed()
+
+    @property
+    def time(self):
+        """target dialect supports representation of Python
+        datetime.time() objects."""
+
+        return exclusions.open()
+
+    @property
+    def time_microseconds(self):
+        """target dialect supports representation of Python
+        datetime.time() with microsecond objects."""
+
+        return exclusions.open()
+
+    @property
+    def binary_comparisons(self):
+        """target database/driver can allow BLOB/BINARY fields to be compared
+        against a bound parameter value.
+        """
+
+        return exclusions.open()
+
+    @property
+    def binary_literals(self):
+        """target backend supports simple binary literals, e.g. an
+        expression like::
+
+            SELECT CAST('foo' AS BINARY)
+
+        Where ``BINARY`` is the type emitted from :class:`.LargeBinary`,
+        e.g. it could be ``BLOB`` or similar.
+
+        Basically fails on Oracle.
+
+        """
+
+        return exclusions.open()
+
+    @property
+    def autocommit(self):
+        """target dialect supports 'AUTOCOMMIT' as an isolation_level"""
+        return exclusions.closed()
+
+    @property
+    def isolation_level(self):
+        """target dialect supports general isolation level settings.
+
+        Note that this requirement, when enabled, also requires that
+        the get_isolation_levels() method be implemented.
+
+        """
+        return exclusions.closed()
+
+    def get_isolation_levels(self, config):
+        """Return a structure of supported isolation levels for the current
+        testing dialect.
+
+        The structure indicates to the testing suite what the expected
+        "default" isolation should be, as well as the other values that
+        are accepted.  The dictionary has two keys, "default" and "supported".
+        The "supported" key refers to a list of all supported levels and
+        it should include AUTOCOMMIT if the dialect supports it.
+
+        If the :meth:`.DefaultRequirements.isolation_level` requirement is
+        not open, then this method has no return value.
+
+        E.g.::
+
+            >>> testing.requirements.get_isolation_levels()
+            {
+                "default": "READ_COMMITTED",
+                "supported": [
+                    "SERIALIZABLE", "READ UNCOMMITTED",
+                    "READ COMMITTED", "REPEATABLE READ",
+                    "AUTOCOMMIT"
+                ]
+            }
+        """
+
+    @property
+    def json_type(self):
+        """target platform implements a native JSON type."""
+
+        return exclusions.closed()
+
+    @property
+    def json_array_indexes(self):
+        """target platform supports numeric array indexes
+        within a JSON structure"""
+
+        return self.json_type
+
+    @property
+    def json_index_supplementary_unicode_element(self):
+        return exclusions.open()
+
+    @property
+    def legacy_unconditional_json_extract(self):
+        """Backend has a JSON_EXTRACT or similar function that returns a
+        valid JSON string in all cases.
+
+        Used to test a legacy feature and is not needed.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def precision_numerics_general(self):
+        """target backend has general support for moderately high-precision
+        numerics."""
+        return exclusions.open()
+
+    @property
+    def precision_numerics_enotation_small(self):
+        """target backend supports Decimal() objects using E notation
+        to represent very small values."""
+        return exclusions.closed()
+
+    @property
+    def precision_numerics_enotation_large(self):
+        """target backend supports Decimal() objects using E notation
+        to represent very large values."""
+        return exclusions.closed()
+
+    @property
+    def precision_numerics_many_significant_digits(self):
+        """target backend supports values with many digits on both sides,
+        such as 319438950232418390.273596, 87673.594069654243
+
+        """
+        return exclusions.closed()
+
+    @property
+    def cast_precision_numerics_many_significant_digits(self):
+        """same as precision_numerics_many_significant_digits but within the
+        context of a CAST statement (hello MySQL)
+
+        """
+        return self.precision_numerics_many_significant_digits
+
+    @property
+    def implicit_decimal_binds(self):
+        """target backend will return a selected Decimal as a Decimal, not
+        a string.
+
+        e.g.::
+
+            expr = decimal.Decimal("15.7563")
+
+            value = e.scalar(
+                select(literal(expr))
+            )
+
+            assert value == expr
+
+        See :ticket:`4036`
+
+        """
+
+        return exclusions.open()
+
+    @property
+    def nested_aggregates(self):
+        """target database can select an aggregate from a subquery that's
+        also using an aggregate
+
+        """
+        return exclusions.open()
+
+    @property
+    def recursive_fk_cascade(self):
+        """target database must support ON DELETE CASCADE on a self-referential
+        foreign key
+
+        """
+        return exclusions.open()
+
+    @property
+    def precision_numerics_retains_significant_digits(self):
+        """A precision numeric type will return empty significant digits,
+        i.e. a value such as 10.000 will come back in Decimal form with
+        the .000 maintained."""
+
+        return exclusions.closed()
+
+    @property
+    def infinity_floats(self):
+        """The Float type can persist and load float('inf'), float('-inf')."""
+
+        return exclusions.closed()
+
+    @property
+    def precision_generic_float_type(self):
+        """target backend will return native floating point numbers with at
+        least seven decimal places when using the generic Float type.
+
+        """
+        return exclusions.open()
+
+    @property
+    def floats_to_four_decimals(self):
+        """target backend can return a floating-point number with four
+        significant digits (such as 15.7563) accurately
+        (i.e. without FP inaccuracies, such as 15.75629997253418).
+
+        """
+        return exclusions.open()
+
+    @property
+    def fetch_null_from_numeric(self):
+        """target backend doesn't crash when you try to select a NUMERIC
+        value that has a value of NULL.
+
+        Added to support Pyodbc bug #351.
+        """
+
+        return exclusions.open()
+
+    @property
+    def text_type(self):
+        """Target database must support an unbounded Text() "
+        "type such as TEXT or CLOB"""
+
+        return exclusions.open()
+
+    @property
+    def empty_strings_varchar(self):
+        """target database can persist/return an empty string with a
+        varchar.
+
+        """
+        return exclusions.open()
+
+    @property
+    def empty_strings_text(self):
+        """target database can persist/return an empty string with an
+        unbounded text."""
+
+        return exclusions.open()
+
+    @property
+    def expressions_against_unbounded_text(self):
+        """target database supports use of an unbounded textual field in a
+        WHERE clause."""
+
+        return exclusions.open()
+
+    @property
+    def selectone(self):
+        """target driver must support the literal statement 'select 1'"""
+        return exclusions.open()
+
+    @property
+    def savepoints(self):
+        """Target database must support savepoints."""
+
+        return exclusions.closed()
+
+    @property
+    def two_phase_transactions(self):
+        """Target database must support two-phase transactions."""
+
+        return exclusions.closed()
+
+    @property
+    def update_from(self):
+        """Target must support UPDATE..FROM syntax"""
+        return exclusions.closed()
+
+    @property
+    def delete_from(self):
+        """Target must support DELETE FROM..FROM or DELETE..USING syntax"""
+        return exclusions.closed()
+
+    @property
+    def update_where_target_in_subquery(self):
+        """Target must support UPDATE (or DELETE) where the same table is
+        present in a subquery in the WHERE clause.
+
+        This is an ANSI-standard syntax that apparently MySQL can't handle,
+        such as::
+
+            UPDATE documents SET flag=1 WHERE documents.title IN
+                (SELECT max(documents.title) AS title
+                    FROM documents GROUP BY documents.user_id
+                )
+
+        """
+        return exclusions.open()
+
+    @property
+    def mod_operator_as_percent_sign(self):
+        """target database must use a plain percent '%' as the 'modulus'
+        operator."""
+        return exclusions.closed()
+
+    @property
+    def percent_schema_names(self):
+        """target backend supports weird identifiers with percent signs
+        in them, e.g. 'some % column'.
+
+        this is a very weird use case but often has problems because of
+        DBAPIs that use python formatting.  It's not a critical use
+        case either.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def order_by_col_from_union(self):
+        """target database supports ordering by a column from a SELECT
+        inside of a UNION
+
+        E.g.  (SELECT id, ...) UNION (SELECT id, ...) ORDER BY id
+
+        """
+        return exclusions.open()
+
+    @property
+    def order_by_label_with_expression(self):
+        """target backend supports ORDER BY a column label within an
+        expression.
+
+        Basically this::
+
+            select data as foo from test order by foo || 'bar'
+
+        Lots of databases including PostgreSQL don't support this,
+        so this is off by default.
+
+        """
+        return exclusions.closed()
+
+    @property
+    def order_by_collation(self):
+        def check(config):
+            try:
+                self.get_order_by_collation(config)
+                return False
+            except NotImplementedError:
+                return True
+
+        return exclusions.skip_if(check)
+
+    def get_order_by_collation(self, config):
+        raise NotImplementedError()
+
+    @property
+    def unicode_connections(self):
+        """Target driver must support non-ASCII characters being passed at
+        all.
+        """
+        return exclusions.open()
+
+    @property
+    def graceful_disconnects(self):
+        """Target driver must raise a DBAPI-level exception, such as
+        InterfaceError, when the underlying connection has been closed
+        and the execute() method is called.
+        """
+        return exclusions.open()
+
+    @property
+    def independent_connections(self):
+        """
+        Target must support simultaneous, independent database connections.
+        """
+        return exclusions.open()
+
+    @property
+    def skip_mysql_on_windows(self):
+        """Catchall for a large variety of MySQL on Windows failures"""
+        return exclusions.open()
+
+    @property
+    def ad_hoc_engines(self):
+        """Test environment must allow ad-hoc engine/connection creation.
+
+        DBs that scale poorly for many connections, even when closed, i.e.
+        Oracle, may use the "--low-connections" option which flags this
+        requirement as not present.
+
+        """
+        return exclusions.skip_if(
+            lambda config: config.options.low_connections
+        )
+
+    @property
+    def no_windows(self):
+        return exclusions.skip_if(self._running_on_windows())
+
+    def _running_on_windows(self):
+        return exclusions.LambdaPredicate(
+            lambda: platform.system() == "Windows",
+            description="running on Windows",
+        )
+
+    @property
+    def timing_intensive(self):
+        return exclusions.requires_tag("timing_intensive")
+
+    @property
+    def memory_intensive(self):
+        return exclusions.requires_tag("memory_intensive")
+
+    @property
+    def threading_with_mock(self):
+        """Mark tests that use threading and mock at the same time - stability
+        issues have been observed with coverage + python 3.3
+
+        """
+        return exclusions.skip_if(
+            lambda config: util.py3k and config.options.has_coverage,
+            "Stability issues with coverage + py3k",
+        )
+
+    @property
+    def sqlalchemy2_stubs(self):
+        def check(config):
+            try:
+                __import__("sqlalchemy-stubs.ext.mypy")
+            except ImportError:
+                return False
+            else:
+                return True
+
+        return exclusions.only_if(check)
+
+    @property
+    def python2(self):
+        return exclusions.skip_if(
+            lambda: sys.version_info >= (3,),
+            "Python version 2.xx is required.",
+        )
+
+    @property
+    def python3(self):
+        return exclusions.skip_if(
+            lambda: sys.version_info < (3,), "Python version 3.xx is required."
+        )
+
+    @property
+    def pep520(self):
+        return self.python36
+
+    @property
+    def insert_order_dicts(self):
+        return self.python37
+
+    @property
+    def python36(self):
+        return exclusions.skip_if(
+            lambda: sys.version_info < (3, 6),
+            "Python version 3.6 or greater is required.",
+        )
+
+    @property
+    def python37(self):
+        return exclusions.skip_if(
+            lambda: sys.version_info < (3, 7),
+            "Python version 3.7 or greater is required.",
+        )
+
+    @property
+    def dataclasses(self):
+        return self.python37
+
+    @property
+    def python38(self):
+        return exclusions.only_if(
+            lambda: util.py38, "Python 3.8 or above required"
+        )
+
+    @property
+    def cpython(self):
+        return exclusions.only_if(
+            lambda: util.cpython, "cPython interpreter needed"
+        )
+
+    @property
+    def patch_library(self):
+        def check_lib():
+            try:
+                __import__("patch")
+            except ImportError:
+                return False
+            else:
+                return True
+
+        return exclusions.only_if(check_lib, "patch library needed")
+
+    @property
+    def non_broken_pickle(self):
+        from sqlalchemy.util import pickle
+
+        return exclusions.only_if(
+            lambda: util.cpython
+            and pickle.__name__ == "cPickle"
+            or sys.version_info >= (3, 2),
+            "Needs cPickle+cPython or newer Python 3 pickle",
+        )
+
+    @property
+    def predictable_gc(self):
+        """target platform must remove all cycles unconditionally when
+        gc.collect() is called, as well as clean out unreferenced subclasses.
+
+        """
+        return self.cpython
+
+    @property
+    def no_coverage(self):
+        """Test should be skipped if coverage is enabled.
+
+        This is to block tests that exercise libraries that seem to be
+        sensitive to coverage, such as PostgreSQL notice logging.
+
+        """
+        return exclusions.skip_if(
+            lambda config: config.options.has_coverage,
+            "Issues observed when coverage is enabled",
+        )
+
+    def _has_mysql_on_windows(self, config):
+        return False
+
+    def _has_mysql_fully_case_sensitive(self, config):
+        return False
+
+    @property
+    def sqlite(self):
+        return exclusions.skip_if(lambda: not self._has_sqlite())
+
+    @property
+    def cextensions(self):
+        return exclusions.skip_if(
+            lambda: not util.has_compiled_ext(), "C extensions not installed"
+        )
+
+    def _has_sqlite(self):
+        from sqlalchemy import create_engine
+
+        try:
+            create_engine("sqlite://")
+            return True
+        except ImportError:
+            return False
+
+    @property
+    def async_dialect(self):
+        """dialect makes use of await_() to invoke operations on the DBAPI."""
+
+        return exclusions.closed()
+
+    @property
+    def asyncio(self):
+        return self.greenlet
+
+    @property
+    def greenlet(self):
+        def go(config):
+            try:
+                import greenlet  # noqa: F401
+            except ImportError:
+                return False
+            else:
+                return True
+
+        return exclusions.only_if(go)
+
+    @property
+    def computed_columns(self):
+        "Supports computed columns"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_stored(self):
+        "Supports computed columns with `persisted=True`"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_virtual(self):
+        "Supports computed columns with `persisted=False`"
+        return exclusions.closed()
+
+    @property
+    def computed_columns_default_persisted(self):
+        """If the default persistence is virtual or stored when `persisted`
+        is omitted"""
+        return exclusions.closed()
+
+    @property
+    def computed_columns_reflect_persisted(self):
+        """If persistence information is returned by the reflection of
+        computed columns"""
+        return exclusions.closed()
+
+    @property
+    def supports_distinct_on(self):
+        """If a backend supports the DISTINCT ON in a select"""
+        return exclusions.closed()
+
+    @property
+    def supports_is_distinct_from(self):
+        """Supports some form of "x IS [NOT] DISTINCT FROM y" construct.
+        Different dialects will implement their own flavour, e.g.,
+        sqlite will emit "x IS NOT y" instead of "x IS DISTINCT FROM y".
+
+        .. seealso::
+
+            :meth:`.ColumnOperators.is_distinct_from`
+
+        """
+        return exclusions.skip_if(
+            lambda config: not config.db.dialect.supports_is_distinct_from,
+            "driver doesn't support an IS DISTINCT FROM construct",
+        )
+
+    @property
+    def identity_columns(self):
+        """If a backend supports GENERATED { ALWAYS | BY DEFAULT }
+        AS IDENTITY"""
+        return exclusions.closed()
+
+    @property
+    def identity_columns_standard(self):
+        """If a backend supports GENERATED { ALWAYS | BY DEFAULT }
+        AS IDENTITY with a standard syntax.
+        This is mainly to exclude MSSql.
+        """
+        return exclusions.closed()
+
+    @property
+    def regexp_match(self):
+        """backend supports the regexp_match operator."""
+        return exclusions.closed()
+
+    @property
+    def regexp_replace(self):
+        """backend supports the regexp_replace operator."""
+        return exclusions.closed()
+
+    @property
+    def fetch_first(self):
+        """backend supports the fetch first clause."""
+        return exclusions.closed()
+
+    @property
+    def fetch_percent(self):
+        """backend supports the fetch first clause with percent."""
+        return exclusions.closed()
+
+    @property
+    def fetch_ties(self):
+        """backend supports the fetch first clause with ties."""
+        return exclusions.closed()
+
+    @property
+    def fetch_no_order_by(self):
+        """backend supports the fetch first without order by"""
+        return exclusions.closed()
+
+    @property
+    def fetch_offset_with_options(self):
+        """backend supports the offset when using fetch first with percent
+        or ties. basically this is "not mssql"
+        """
+        return exclusions.closed()
+
+    @property
+    def fetch_expression(self):
+        """backend supports fetch / offset with expression in them, like
+
+        SELECT * FROM some_table
+        OFFSET 1 + 1 ROWS FETCH FIRST 1 + 1 ROWS ONLY
+        """
+        return exclusions.closed()
+
+    @property
+    def autoincrement_without_sequence(self):
+        """If autoincrement=True on a column does not require an explicit
+        sequence. This should be false only for oracle.
+        """
+        return exclusions.open()
+
+    @property
+    def generic_classes(self):
+        "If X[Y] can be implemented with ``__class_getitem__``. py3.7+"
+        return exclusions.only_if(lambda: util.py37)
-- 
cgit v1.2.3