django/tests/template_tests/test_parser.py

"""
Testing some internals of the template processing.
These are *not* examples to be copied in user code.
"""

from django.template import Library, TemplateSyntaxError
from django.template.base import (
    FilterExpression,
    Lexer,
    Parser,
    Token,
    TokenType,
    Variable,
    VariableDoesNotExist,
)
from django.template.defaultfilters import register as filter_library
from django.test import SimpleTestCase


class ParserTests(SimpleTestCase):
    def test_token_smart_split(self):
        """
        #7027 -- _() syntax should work with spaces
        """
        token = Token(
            TokenType.BLOCK, 'sometag _("Page not found") value|yesno:_("yes,no")'
        )
        split = token.split_contents()
        self.assertEqual(
            split, ["sometag", '_("Page not found")', 'value|yesno:_("yes,no")']
        )

    def test_repr(self):
        token = Token(TokenType.BLOCK, "some text")
        self.assertEqual(repr(token), '<Block token: "some text...">')
        parser = Parser([token], builtins=[filter_library])
        self.assertEqual(
            repr(parser),
            '<Parser tokens=[<Block token: "some text...">]>',
        )
        filter_expression = FilterExpression("news|upper", parser)
        self.assertEqual(repr(filter_expression), "<FilterExpression 'news|upper'>")
        lexer = Lexer("{% for i in 1 %}{{ a }}\n{% endfor %}")
        self.assertEqual(
            repr(lexer),
            '<Lexer template_string="{% for i in 1 %}{{ a...", verbatim=False>',
        )

    def test_filter_parsing(self):
        c = {"article": {"section": "News"}}
        p = Parser("", builtins=[filter_library])

        def fe_test(s, val):
            self.assertEqual(FilterExpression(s, p).resolve(c), val)

        fe_test("article.section", "News")
        fe_test("article.section|upper", "NEWS")
        fe_test('"News"', "News")
        fe_test("'News'", "News")
        fe_test(r'"Some \"Good\" News"', 'Some "Good" News')
        fe_test(r'"Some \"Good\" News"', 'Some "Good" News')
        fe_test(r"'Some \'Bad\' News'", "Some 'Bad' News")

        fe = FilterExpression(r'"Some \"Good\" News"', p)
        self.assertEqual(fe.filters, [])
        self.assertEqual(fe.var, 'Some "Good" News')

        # Filtered variables should reject access of attributes beginning with
        # underscores.
        msg = (
            "Variables and attributes may not begin with underscores: 'article._hidden'"
        )
        with self.assertRaisesMessage(TemplateSyntaxError, msg):
            FilterExpression("article._hidden|upper", p)

    def test_cannot_parse_characters(self):
        p = Parser("", builtins=[filter_library])
        for filter_expression, characters in [
            ('<>|default:"Default"|upper', '|<>||default:"Default"|upper'),
            ("test|<>|upper", "test||<>||upper"),
        ]:
            with self.subTest(filter_expression=filter_expression):
                with self.assertRaisesMessage(
                    TemplateSyntaxError,
                    f"Could not parse some characters: {characters}",
                ):
                    FilterExpression(filter_expression, p)

    def test_cannot_find_variable(self):
        p = Parser("", builtins=[filter_library])
        with self.assertRaisesMessage(
            TemplateSyntaxError,
            'Could not find variable at start of |default:"Default"',
        ):
            FilterExpression('|default:"Default"', p)

    def test_variable_parsing(self):
        c = {"article": {"section": "News"}}
        self.assertEqual(Variable("article.section").resolve(c), "News")
        self.assertEqual(Variable('"News"').resolve(c), "News")
        self.assertEqual(Variable("'News'").resolve(c), "News")

        # Translated strings are handled correctly.
        self.assertEqual(Variable("_(article.section)").resolve(c), "News")
        self.assertEqual(Variable('_("Good News")').resolve(c), "Good News")
        self.assertEqual(Variable("_('Better News')").resolve(c), "Better News")

        # Escaped quotes work correctly as well.
        self.assertEqual(
            Variable(r'"Some \"Good\" News"').resolve(c), 'Some "Good" News'
        )
        self.assertEqual(
            Variable(r"'Some \'Better\' News'").resolve(c), "Some 'Better' News"
        )

        # Variables should reject access of attributes and variables beginning
        # with underscores.
        for name in ["article._hidden", "_article"]:
            msg = f"Variables and attributes may not begin with underscores: '{name}'"
            with self.assertRaisesMessage(TemplateSyntaxError, msg):
                Variable(name)

        # Variables should raise on non string type
        with self.assertRaisesMessage(
            TypeError, "Variable must be a string or number, got <class 'dict'>"
        ):
            Variable({})

    def test_filter_args_count(self):
        parser = Parser("")
        register = Library()

        @register.filter
        def no_arguments(value):
            pass

        @register.filter
        def one_argument(value, arg):
            pass

        @register.filter
        def one_opt_argument(value, arg=False):
            pass

        @register.filter
        def two_arguments(value, arg, arg2):
            pass

        @register.filter
        def two_one_opt_arg(value, arg, arg2=False):
            pass

        parser.add_library(register)
        for expr in (
            '1|no_arguments:"1"',
            "1|two_arguments",
            '1|two_arguments:"1"',
            "1|two_one_opt_arg",
        ):
            with self.assertRaises(TemplateSyntaxError):
                FilterExpression(expr, parser)
        for expr in (
            # Correct number of arguments
            "1|no_arguments",
            '1|one_argument:"1"',
            # One optional
            "1|one_opt_argument",
            '1|one_opt_argument:"1"',
            # Not supplying all
            '1|two_one_opt_arg:"1"',
        ):
            FilterExpression(expr, parser)

    def test_filter_numeric_argument_parsing(self):
        p = Parser("", builtins=[filter_library])

        cases = {
            "5": 5,
            "-5": -5,
            "5.2": 5.2,
            ".4": 0.4,
            "5.2e3": 5200.0,  # 5.2 × 10³ = 5200.0.
            "5.2E3": 5200.0,  # Case-insensitive.
            "5.2e-3": 0.0052,  # Negative exponent.
            "-1.5E4": -15000.0,
            "+3.0e2": 300.0,
            ".5e2": 50.0,  # 0.5 × 10² = 50.0
        }
        for num, expected in cases.items():
            with self.subTest(num=num):
                self.assertEqual(FilterExpression(num, p).resolve({}), expected)
                self.assertEqual(
                    FilterExpression(f"0|default:{num}", p).resolve({}), expected
                )

        invalid_numbers = [
            "abc123",
            "123abc",
            "foo",
            "error",
            "1e",
            "e400",
            "1e.2",
            "1e2.",
            "1e2.0",
            "1e2a",
            "1e2e3",
            "1e-",
            "1e-a",
        ]

        for num in invalid_numbers:
            with self.subTest(num=num):
                self.assertIsNone(
                    FilterExpression(num, p).resolve({}, ignore_failures=True)
                )
                with self.assertRaises(VariableDoesNotExist):
                    FilterExpression(f"0|default:{num}", p).resolve({})