sqlalchemy/test/sql/test_quote.py

from sqlalchemy import CheckConstraint
from sqlalchemy import Column
from sqlalchemy import column
from sqlalchemy import ForeignKey
from sqlalchemy import Index
from sqlalchemy import inspect
from sqlalchemy import Integer
from sqlalchemy import MetaData
from sqlalchemy import schema
from sqlalchemy import select
from sqlalchemy import sql
from sqlalchemy import Table
from sqlalchemy import testing
from sqlalchemy.engine import default
from sqlalchemy.sql import compiler
from sqlalchemy.sql.elements import _anonymous_label
from sqlalchemy.sql.elements import quoted_name
from sqlalchemy.testing import AssertsCompiledSQL
from sqlalchemy.testing import eq_
from sqlalchemy.testing import fixtures
from sqlalchemy.testing.util import picklers


class QuoteExecTest(fixtures.TestBase):
    __backend__ = True

    @classmethod
    def setup_class(cls):
        # TODO: figure out which databases/which identifiers allow special
        # characters to be used, such as: spaces, quote characters,
        # punctuation characters, set up tests for those as well.

        global table1, table2
        metadata = MetaData(testing.db)

        table1 = Table(
            "WorstCase1",
            metadata,
            Column("lowercase", Integer, primary_key=True),
            Column("UPPERCASE", Integer),
            Column("MixedCase", Integer),
            Column("ASC", Integer, key="a123"),
        )
        table2 = Table(
            "WorstCase2",
            metadata,
            Column("desc", Integer, primary_key=True, key="d123"),
            Column("Union", Integer, key="u123"),
            Column("MixedCase", Integer),
        )

        table1.create()
        table2.create()

    def teardown(self):
        table1.delete().execute()
        table2.delete().execute()

    @classmethod
    def teardown_class(cls):
        table1.drop()
        table2.drop()

    def test_reflect(self):
        meta2 = MetaData(testing.db)
        t2 = Table("WorstCase1", meta2, autoload=True, quote=True)
        assert "lowercase" in t2.c

        # indicates the DB returns unquoted names as
        # UPPERCASE, which we then assume are unquoted and go to
        # lower case.  So we cannot accurately reflect quoted UPPERCASE
        # names from a "name normalize" backend, as they cannot be
        # distinguished from case-insensitive/unquoted names.
        if testing.db.dialect.requires_name_normalize:
            assert "uppercase" in t2.c
        else:
            assert "UPPERCASE" in t2.c

        # ASC OTOH is a reserved word, which is always quoted, so
        # with that name we keep the quotes on and it stays uppercase
        # regardless.  Seems a little weird, though.
        assert "ASC" in t2.c

        assert "MixedCase" in t2.c

    @testing.provide_metadata
    def test_has_table_case_sensitive(self):
        preparer = testing.db.dialect.identifier_preparer
        if testing.db.dialect.requires_name_normalize:
            testing.db.execute("CREATE TABLE TAB1 (id INTEGER)")
        else:
            testing.db.execute("CREATE TABLE tab1 (id INTEGER)")
        testing.db.execute(
            "CREATE TABLE %s (id INTEGER)" % preparer.quote_identifier("tab2")
        )
        testing.db.execute(
            "CREATE TABLE %s (id INTEGER)" % preparer.quote_identifier("TAB3")
        )
        testing.db.execute(
            "CREATE TABLE %s (id INTEGER)" % preparer.quote_identifier("TAB4")
        )

        t1 = Table(
            "tab1", self.metadata, Column("id", Integer, primary_key=True)
        )
        t2 = Table(
            "tab2",
            self.metadata,
            Column("id", Integer, primary_key=True),
            quote=True,
        )
        t3 = Table(
            "TAB3", self.metadata, Column("id", Integer, primary_key=True)
        )
        t4 = Table(
            "TAB4",
            self.metadata,
            Column("id", Integer, primary_key=True),
            quote=True,
        )

        insp = inspect(testing.db)
        assert testing.db.has_table(t1.name)
        eq_([c["name"] for c in insp.get_columns(t1.name)], ["id"])

        assert testing.db.has_table(t2.name)
        eq_([c["name"] for c in insp.get_columns(t2.name)], ["id"])

        assert testing.db.has_table(t3.name)
        eq_([c["name"] for c in insp.get_columns(t3.name)], ["id"])

        assert testing.db.has_table(t4.name)
        eq_([c["name"] for c in insp.get_columns(t4.name)], ["id"])

    def test_basic(self):
        table1.insert().execute(
            {"lowercase": 1, "UPPERCASE": 2, "MixedCase": 3, "a123": 4},
            {"lowercase": 2, "UPPERCASE": 2, "MixedCase": 3, "a123": 4},
            {"lowercase": 4, "UPPERCASE": 3, "MixedCase": 2, "a123": 1},
        )
        table2.insert().execute(
            {"d123": 1, "u123": 2, "MixedCase": 3},
            {"d123": 2, "u123": 2, "MixedCase": 3},
            {"d123": 4, "u123": 3, "MixedCase": 2},
        )

        columns = [
            table1.c.lowercase,
            table1.c.UPPERCASE,
            table1.c.MixedCase,
            table1.c.a123,
        ]
        result = select(columns).execute().fetchall()
        assert result == [(1, 2, 3, 4), (2, 2, 3, 4), (4, 3, 2, 1)]

        columns = [table2.c.d123, table2.c.u123, table2.c.MixedCase]
        result = select(columns).execute().fetchall()
        assert result == [(1, 2, 3), (2, 2, 3), (4, 3, 2)]

    def test_use_labels(self):
        table1.insert().execute(
            {"lowercase": 1, "UPPERCASE": 2, "MixedCase": 3, "a123": 4},
            {"lowercase": 2, "UPPERCASE": 2, "MixedCase": 3, "a123": 4},
            {"lowercase": 4, "UPPERCASE": 3, "MixedCase": 2, "a123": 1},
        )
        table2.insert().execute(
            {"d123": 1, "u123": 2, "MixedCase": 3},
            {"d123": 2, "u123": 2, "MixedCase": 3},
            {"d123": 4, "u123": 3, "MixedCase": 2},
        )

        columns = [
            table1.c.lowercase,
            table1.c.UPPERCASE,
            table1.c.MixedCase,
            table1.c.a123,
        ]
        result = select(columns, use_labels=True).execute().fetchall()
        assert result == [(1, 2, 3, 4), (2, 2, 3, 4), (4, 3, 2, 1)]

        columns = [table2.c.d123, table2.c.u123, table2.c.MixedCase]
        result = select(columns, use_labels=True).execute().fetchall()
        assert result == [(1, 2, 3), (2, 2, 3), (4, 3, 2)]


class QuoteTest(fixtures.TestBase, AssertsCompiledSQL):
    __dialect__ = "default"

    @classmethod
    def setup_class(cls):
        # TODO: figure out which databases/which identifiers allow special
        # characters to be used, such as: spaces, quote characters,
        # punctuation characters, set up tests for those as well.

        global table1, table2
        metadata = MetaData(testing.db)

        table1 = Table(
            "WorstCase1",
            metadata,
            Column("lowercase", Integer, primary_key=True),
            Column("UPPERCASE", Integer),
            Column("MixedCase", Integer),
            Column("ASC", Integer, key="a123"),
        )
        table2 = Table(
            "WorstCase2",
            metadata,
            Column("desc", Integer, primary_key=True, key="d123"),
            Column("Union", Integer, key="u123"),
            Column("MixedCase", Integer),
        )

    @testing.crashes("oracle", "FIXME: unknown, verify not fails_on")
    @testing.requires.subqueries
    def test_labels(self):
        """test the quoting of labels.

        If labels aren't quoted, a query in postgresql in particular will
        fail since it produces::

            SELECT
                LaLa.lowercase, LaLa."UPPERCASE", LaLa."MixedCase", LaLa."ASC"
            FROM (
                SELECT DISTINCT
                    "WorstCase1".lowercase AS lowercase,
                    "WorstCase1"."UPPERCASE" AS UPPERCASE,
                    "WorstCase1"."MixedCase" AS MixedCase,
                    "WorstCase1"."ASC" AS ASC
                FROM "WorstCase1"
            ) AS LaLa

        where the "UPPERCASE" column of "LaLa" doesn't exist.
        """

        self.assert_compile(
            table1.select(distinct=True).alias("LaLa").select(),
            "SELECT "
            '"LaLa".lowercase, '
            '"LaLa"."UPPERCASE", '
            '"LaLa"."MixedCase", '
            '"LaLa"."ASC" '
            "FROM ("
            "SELECT DISTINCT "
            '"WorstCase1".lowercase AS lowercase, '
            '"WorstCase1"."UPPERCASE" AS "UPPERCASE", '
            '"WorstCase1"."MixedCase" AS "MixedCase", '
            '"WorstCase1"."ASC" AS "ASC" '
            'FROM "WorstCase1"'
            ') AS "LaLa"',
        )

    def test_lower_case_names(self):
        # Create table with quote defaults
        metadata = MetaData()
        t1 = Table("t1", metadata, Column("col1", Integer), schema="foo")

        # Note that the names are not quoted b/c they are all lower case
        result = "CREATE TABLE foo.t1 (col1 INTEGER)"
        self.assert_compile(schema.CreateTable(t1), result)

        # Create the same table with quotes set to True now
        metadata = MetaData()
        t1 = Table(
            "t1",
            metadata,
            Column("col1", Integer, quote=True),
            schema="foo",
            quote=True,
            quote_schema=True,
        )

        # Note that the names are now quoted
        result = 'CREATE TABLE "foo"."t1" ("col1" INTEGER)'
        self.assert_compile(schema.CreateTable(t1), result)

    def test_upper_case_names(self):
        # Create table with quote defaults
        metadata = MetaData()
        t1 = Table("TABLE1", metadata, Column("COL1", Integer), schema="FOO")

        # Note that the names are quoted b/c they are not all lower case
        result = 'CREATE TABLE "FOO"."TABLE1" ("COL1" INTEGER)'
        self.assert_compile(schema.CreateTable(t1), result)

        # Create the same table with quotes set to False now
        metadata = MetaData()
        t1 = Table(
            "TABLE1",
            metadata,
            Column("COL1", Integer, quote=False),
            schema="FOO",
            quote=False,
            quote_schema=False,
        )

        # Note that the names are now unquoted
        result = "CREATE TABLE FOO.TABLE1 (COL1 INTEGER)"
        self.assert_compile(schema.CreateTable(t1), result)

    def test_mixed_case_names(self):
        # Create table with quote defaults
        metadata = MetaData()
        t1 = Table("Table1", metadata, Column("Col1", Integer), schema="Foo")

        # Note that the names are quoted b/c they are not all lower case
        result = 'CREATE TABLE "Foo"."Table1" ("Col1" INTEGER)'
        self.assert_compile(schema.CreateTable(t1), result)

        # Create the same table with quotes set to False now
        metadata = MetaData()
        t1 = Table(
            "Table1",
            metadata,
            Column("Col1", Integer, quote=False),
            schema="Foo",
            quote=False,
            quote_schema=False,
        )

        # Note that the names are now unquoted
        result = "CREATE TABLE Foo.Table1 (Col1 INTEGER)"
        self.assert_compile(schema.CreateTable(t1), result)

    def test_numeric_initial_char(self):
        # Create table with quote defaults
        metadata = MetaData()
        t1 = Table(
            "35table", metadata, Column("25column", Integer), schema="45schema"
        )

        # Note that the names are quoted b/c the initial
        # character is in ['$','0', '1' ... '9']
        result = 'CREATE TABLE "45schema"."35table" ("25column" INTEGER)'
        self.assert_compile(schema.CreateTable(t1), result)

        # Create the same table with quotes set to False now
        metadata = MetaData()
        t1 = Table(
            "35table",
            metadata,
            Column("25column", Integer, quote=False),
            schema="45schema",
            quote=False,
            quote_schema=False,
        )

        # Note that the names are now unquoted
        result = "CREATE TABLE 45schema.35table (25column INTEGER)"
        self.assert_compile(schema.CreateTable(t1), result)

    def test_illegal_initial_char(self):
        # Create table with quote defaults
        metadata = MetaData()
        t1 = Table(
            "$table", metadata, Column("$column", Integer), schema="$schema"
        )

        # Note that the names are quoted b/c the initial
        # character is in ['$','0', '1' ... '9']
        result = 'CREATE TABLE "$schema"."$table" ("$column" INTEGER)'
        self.assert_compile(schema.CreateTable(t1), result)

        # Create the same table with quotes set to False now
        metadata = MetaData()
        t1 = Table(
            "$table",
            metadata,
            Column("$column", Integer, quote=False),
            schema="$schema",
            quote=False,
            quote_schema=False,
        )

        # Note that the names are now unquoted
        result = "CREATE TABLE $schema.$table ($column INTEGER)"
        self.assert_compile(schema.CreateTable(t1), result)

    def test_reserved_words(self):
        # Create table with quote defaults
        metadata = MetaData()
        table = Table(
            "foreign",
            metadata,
            Column("col1", Integer),
            Column("from", Integer),
            Column("order", Integer),
            schema="create",
        )

        # Note that the names are quoted b/c they are reserved words
        x = select([table.c.col1, table.c["from"], table.c.order])
        self.assert_compile(
            x,
            "SELECT "
            '"create"."foreign".col1, '
            '"create"."foreign"."from", '
            '"create"."foreign"."order" '
            'FROM "create"."foreign"',
        )

        # Create the same table with quotes set to False now
        metadata = MetaData()
        table = Table(
            "foreign",
            metadata,
            Column("col1", Integer),
            Column("from", Integer, quote=False),
            Column("order", Integer, quote=False),
            schema="create",
            quote=False,
            quote_schema=False,
        )

        # Note that the names are now unquoted
        x = select([table.c.col1, table.c["from"], table.c.order])
        self.assert_compile(
            x,
            "SELECT "
            "create.foreign.col1, "
            "create.foreign.from, "
            "create.foreign.order "
            "FROM create.foreign",
        )

    def test_subquery_one(self):
        # Lower case names, should not quote
        metadata = MetaData()
        t1 = Table("t1", metadata, Column("col1", Integer), schema="foo")
        a = t1.select().alias("anon")
        b = select([1], a.c.col1 == 2, from_obj=a)
        self.assert_compile(
            b,
            "SELECT 1 "
            "FROM ("
            "SELECT "
            "foo.t1.col1 AS col1 "
            "FROM "
            "foo.t1"
            ") AS anon "
            "WHERE anon.col1 = :col1_1",
        )

    def test_subquery_two(self):
        # Lower case names, quotes on, should quote
        metadata = MetaData()
        t1 = Table(
            "t1",
            metadata,
            Column("col1", Integer, quote=True),
            schema="foo",
            quote=True,
            quote_schema=True,
        )
        a = t1.select().alias("anon")
        b = select([1], a.c.col1 == 2, from_obj=a)
        self.assert_compile(
            b,
            "SELECT 1 "
            "FROM ("
            "SELECT "
            '"foo"."t1"."col1" AS "col1" '
            "FROM "
            '"foo"."t1"'
            ") AS anon "
            'WHERE anon."col1" = :col1_1',
        )

    def test_subquery_three(self):
        # Not lower case names, should quote
        metadata = MetaData()
        t1 = Table("T1", metadata, Column("Col1", Integer), schema="Foo")
        a = t1.select().alias("Anon")
        b = select([1], a.c.Col1 == 2, from_obj=a)
        self.assert_compile(
            b,
            "SELECT 1 "
            "FROM ("
            "SELECT "
            '"Foo"."T1"."Col1" AS "Col1" '
            "FROM "
            '"Foo"."T1"'
            ') AS "Anon" '
            "WHERE "
            '"Anon"."Col1" = :Col1_1',
        )

    def test_subquery_four(self):

        # Not lower case names, quotes off, should not quote
        metadata = MetaData()
        t1 = Table(
            "T1",
            metadata,
            Column("Col1", Integer, quote=False),
            schema="Foo",
            quote=False,
            quote_schema=False,
        )
        a = t1.select().alias("Anon")
        b = select([1], a.c.Col1 == 2, from_obj=a)
        self.assert_compile(
            b,
            "SELECT 1 "
            "FROM ("
            "SELECT "
            "Foo.T1.Col1 AS Col1 "
            "FROM "
            "Foo.T1"
            ') AS "Anon" '
            "WHERE "
            '"Anon".Col1 = :Col1_1',
        )

    def test_simple_order_by_label(self):
        m = MetaData()
        t1 = Table("t1", m, Column("col1", Integer))
        cl = t1.c.col1.label("ShouldQuote")
        self.assert_compile(
            select([cl]).order_by(cl),
            'SELECT t1.col1 AS "ShouldQuote" FROM t1 ORDER BY "ShouldQuote"',
        )

    def test_collate(self):
        self.assert_compile(column("foo").collate("utf8"), "foo COLLATE utf8")

        self.assert_compile(
            column("foo").collate("fr_FR"),
            'foo COLLATE "fr_FR"',
            dialect="postgresql",
        )

        self.assert_compile(
            column("foo").collate("utf8_GERMAN_ci"),
            "foo COLLATE `utf8_GERMAN_ci`",
            dialect="mysql",
        )

        self.assert_compile(
            column("foo").collate("SQL_Latin1_General_CP1_CI_AS"),
            "foo COLLATE SQL_Latin1_General_CP1_CI_AS",
            dialect="mssql",
        )

    def test_join(self):
        # Lower case names, should not quote
        metadata = MetaData()
        t1 = Table("t1", metadata, Column("col1", Integer))
        t2 = Table(
            "t2",
            metadata,
            Column("col1", Integer),
            Column("t1col1", Integer, ForeignKey("t1.col1")),
        )
        self.assert_compile(
            t2.join(t1).select(),
            "SELECT "
            "t2.col1, t2.t1col1, t1.col1 "
            "FROM "
            "t2 "
            "JOIN "
            "t1 ON t1.col1 = t2.t1col1",
        )

        # Lower case names, quotes on, should quote
        metadata = MetaData()
        t1 = Table(
            "t1", metadata, Column("col1", Integer, quote=True), quote=True
        )
        t2 = Table(
            "t2",
            metadata,
            Column("col1", Integer, quote=True),
            Column("t1col1", Integer, ForeignKey("t1.col1"), quote=True),
            quote=True,
        )
        self.assert_compile(
            t2.join(t1).select(),
            "SELECT "
            '"t2"."col1", "t2"."t1col1", "t1"."col1" '
            "FROM "
            '"t2" '
            "JOIN "
            '"t1" ON "t1"."col1" = "t2"."t1col1"',
        )

        # Not lower case names, should quote
        metadata = MetaData()
        t1 = Table("T1", metadata, Column("Col1", Integer))
        t2 = Table(
            "T2",
            metadata,
            Column("Col1", Integer),
            Column("T1Col1", Integer, ForeignKey("T1.Col1")),
        )
        self.assert_compile(
            t2.join(t1).select(),
            "SELECT "
            '"T2"."Col1", "T2"."T1Col1", "T1"."Col1" '
            "FROM "
            '"T2" '
            "JOIN "
            '"T1" ON "T1"."Col1" = "T2"."T1Col1"',
        )

        # Not lower case names, quotes off, should not quote
        metadata = MetaData()
        t1 = Table(
            "T1", metadata, Column("Col1", Integer, quote=False), quote=False
        )
        t2 = Table(
            "T2",
            metadata,
            Column("Col1", Integer, quote=False),
            Column("T1Col1", Integer, ForeignKey("T1.Col1"), quote=False),
            quote=False,
        )
        self.assert_compile(
            t2.join(t1).select(),
            "SELECT "
            "T2.Col1, T2.T1Col1, T1.Col1 "
            "FROM "
            "T2 "
            "JOIN "
            "T1 ON T1.Col1 = T2.T1Col1",
        )

    def test_label_and_alias(self):
        # Lower case names, should not quote
        metadata = MetaData()
        table = Table("t1", metadata, Column("col1", Integer))
        x = select([table.c.col1.label("label1")]).alias("alias1")
        self.assert_compile(
            select([x.c.label1]),
            "SELECT "
            "alias1.label1 "
            "FROM ("
            "SELECT "
            "t1.col1 AS label1 "
            "FROM t1"
            ") AS alias1",
        )

        # Not lower case names, should quote
        metadata = MetaData()
        table = Table("T1", metadata, Column("Col1", Integer))
        x = select([table.c.Col1.label("Label1")]).alias("Alias1")
        self.assert_compile(
            select([x.c.Label1]),
            "SELECT "
            '"Alias1"."Label1" '
            "FROM ("
            "SELECT "
            '"T1"."Col1" AS "Label1" '
            'FROM "T1"'
            ') AS "Alias1"',
        )

    def test_literal_column_already_with_quotes(self):
        # Lower case names
        metadata = MetaData()
        table = Table("t1", metadata, Column("col1", Integer))

        # Note that 'col1' is already quoted (literal_column)
        columns = [sql.literal_column("'col1'").label("label1")]
        x = select(columns, from_obj=[table]).alias("alias1")
        x = x.select()
        self.assert_compile(
            x,
            "SELECT "
            "alias1.label1 "
            "FROM ("
            "SELECT "
            "'col1' AS label1 "
            "FROM t1"
            ") AS alias1",
        )

        # Not lower case names
        metadata = MetaData()
        table = Table("T1", metadata, Column("Col1", Integer))

        # Note that 'Col1' is already quoted (literal_column)
        columns = [sql.literal_column("'Col1'").label("Label1")]
        x = select(columns, from_obj=[table]).alias("Alias1")
        x = x.select()
        self.assert_compile(
            x,
            "SELECT "
            '"Alias1"."Label1" '
            "FROM ("
            "SELECT "
            "'Col1' AS \"Label1\" "
            'FROM "T1"'
            ') AS "Alias1"',
        )

    def test_apply_labels_should_quote(self):
        # Not lower case names, should quote
        metadata = MetaData()
        t1 = Table("T1", metadata, Column("Col1", Integer), schema="Foo")

        self.assert_compile(
            t1.select().apply_labels(),
            "SELECT "
            '"Foo"."T1"."Col1" AS "Foo_T1_Col1" '
            "FROM "
            '"Foo"."T1"',
        )

    def test_apply_labels_shouldnt_quote(self):
        # Not lower case names, quotes off
        metadata = MetaData()
        t1 = Table(
            "T1",
            metadata,
            Column("Col1", Integer, quote=False),
            schema="Foo",
            quote=False,
            quote_schema=False,
        )

        # TODO: is this what we really want here ?
        # what if table/schema *are* quoted?
        self.assert_compile(
            t1.select().apply_labels(),
            "SELECT " "Foo.T1.Col1 AS Foo_T1_Col1 " "FROM " "Foo.T1",
        )

    def test_quote_flag_propagate_check_constraint(self):
        m = MetaData()
        t = Table("t", m, Column("x", Integer, quote=True))
        CheckConstraint(t.c.x > 5)
        self.assert_compile(
            schema.CreateTable(t),
            "CREATE TABLE t (" '"x" INTEGER, ' 'CHECK ("x" > 5)' ")",
        )

    def test_quote_flag_propagate_index(self):
        m = MetaData()
        t = Table("t", m, Column("x", Integer, quote=True))
        idx = Index("foo", t.c.x)
        self.assert_compile(
            schema.CreateIndex(idx), 'CREATE INDEX foo ON t ("x")'
        )

    def test_quote_flag_propagate_anon_label(self):
        m = MetaData()
        t = Table("t", m, Column("x", Integer, quote=True))

        self.assert_compile(
            select([t.alias()]).apply_labels(),
            'SELECT t_1."x" AS "t_1_x" FROM t AS t_1',
        )

        t2 = Table("t2", m, Column("x", Integer), quote=True)
        self.assert_compile(
            select([t2.c.x]).apply_labels(),
            'SELECT "t2".x AS "t2_x" FROM "t2"',
        )


class PreparerTest(fixtures.TestBase):

    """Test the db-agnostic quoting services of IdentifierPreparer."""

    def test_unformat(self):
        prep = compiler.IdentifierPreparer(default.DefaultDialect())
        unformat = prep.unformat_identifiers

        def a_eq(have, want):
            if have != want:
                print("Wanted %s" % want)
                print("Received %s" % have)
            self.assert_(have == want)

        a_eq(unformat("foo"), ["foo"])
        a_eq(unformat('"foo"'), ["foo"])
        a_eq(unformat("'foo'"), ["'foo'"])
        a_eq(unformat("foo.bar"), ["foo", "bar"])
        a_eq(unformat('"foo"."bar"'), ["foo", "bar"])
        a_eq(unformat('foo."bar"'), ["foo", "bar"])
        a_eq(unformat('"foo".bar'), ["foo", "bar"])
        a_eq(unformat('"foo"."b""a""r"."baz"'), ["foo", 'b"a"r', "baz"])

    def test_unformat_custom(self):
        class Custom(compiler.IdentifierPreparer):
            def __init__(self, dialect):
                super(Custom, self).__init__(
                    dialect, initial_quote="`", final_quote="`"
                )

            def _escape_identifier(self, value):
                return value.replace("`", "``")

            def _unescape_identifier(self, value):
                return value.replace("``", "`")

        prep = Custom(default.DefaultDialect())
        unformat = prep.unformat_identifiers

        def a_eq(have, want):
            if have != want:
                print("Wanted %s" % want)
                print("Received %s" % have)
            self.assert_(have == want)

        a_eq(unformat("foo"), ["foo"])
        a_eq(unformat("`foo`"), ["foo"])
        a_eq(unformat(repr("foo")), ["'foo'"])
        a_eq(unformat("foo.bar"), ["foo", "bar"])
        a_eq(unformat("`foo`.`bar`"), ["foo", "bar"])
        a_eq(unformat("foo.`bar`"), ["foo", "bar"])
        a_eq(unformat("`foo`.bar"), ["foo", "bar"])
        a_eq(unformat("`foo`.`b``a``r`.`baz`"), ["foo", "b`a`r", "baz"])


class QuotedIdentTest(fixtures.TestBase):
    def test_concat_quotetrue(self):
        q1 = quoted_name("x", True)
        self._assert_not_quoted("y" + q1)

    def test_concat_quotefalse(self):
        q1 = quoted_name("x", False)
        self._assert_not_quoted("y" + q1)

    def test_concat_quotenone(self):
        q1 = quoted_name("x", None)
        self._assert_not_quoted("y" + q1)

    def test_rconcat_quotetrue(self):
        q1 = quoted_name("x", True)
        self._assert_not_quoted("y" + q1)

    def test_rconcat_quotefalse(self):
        q1 = quoted_name("x", False)
        self._assert_not_quoted("y" + q1)

    def test_rconcat_quotenone(self):
        q1 = quoted_name("x", None)
        self._assert_not_quoted("y" + q1)

    def test_concat_anon(self):
        q1 = _anonymous_label(quoted_name("x", True))
        assert isinstance(q1, _anonymous_label)
        value = q1 + "y"
        assert isinstance(value, _anonymous_label)
        self._assert_quoted(value, True)

    def test_rconcat_anon(self):
        q1 = _anonymous_label(quoted_name("x", True))
        assert isinstance(q1, _anonymous_label)
        value = "y" + q1
        assert isinstance(value, _anonymous_label)
        self._assert_quoted(value, True)

    def test_coerce_quoted_switch(self):
        q1 = quoted_name("x", False)
        q2 = quoted_name(q1, True)
        eq_(q2.quote, True)

    def test_coerce_quoted_none(self):
        q1 = quoted_name("x", False)
        q2 = quoted_name(q1, None)
        eq_(q2.quote, False)

    def test_coerce_quoted_retain(self):
        q1 = quoted_name("x", False)
        q2 = quoted_name(q1, False)
        eq_(q2.quote, False)

    def test_coerce_none(self):
        q1 = quoted_name(None, False)
        eq_(q1, None)

    def test_apply_map_quoted(self):
        q1 = _anonymous_label(quoted_name("x%s", True))
        q2 = q1.apply_map(("bar"))
        eq_(q2, "xbar")
        eq_(q2.quote, True)

    def test_apply_map_plain(self):
        q1 = _anonymous_label(quoted_name("x%s", None))
        q2 = q1.apply_map(("bar"))
        eq_(q2, "xbar")
        self._assert_not_quoted(q2)

    def test_pickle_quote(self):
        q1 = quoted_name("x", True)
        for loads, dumps in picklers():
            q2 = loads(dumps(q1))
            eq_(str(q1), str(q2))
            eq_(q1.quote, q2.quote)

    def test_pickle_anon_label(self):
        q1 = _anonymous_label(quoted_name("x", True))
        for loads, dumps in picklers():
            q2 = loads(dumps(q1))
            assert isinstance(q2, _anonymous_label)
            eq_(str(q1), str(q2))
            eq_(q1.quote, q2.quote)

    def _assert_quoted(self, value, quote):
        assert isinstance(value, quoted_name)
        eq_(value.quote, quote)

    def _assert_not_quoted(self, value):
        assert not isinstance(value, quoted_name)