examples/basic/test.py fails with what appears to be a parse error

[mdaniel]

Running examples/basic/test.py fails/has been failing with what appears to be a parse error since jinja 2.8 up to and including 3.1.4

this is slightly pseudocode since older versions don't install cleanly; I can provide the real one if it is necessary

for i in $(git tag | sed -e '/rc/d; /\.x/d; /a[0-9]/d'); do 
    py_env="venv$i"
    python3 -m venv "$py_env"
    git checkout --force $i
    $py_env/bin/pip install .
    $py_env/bin/python -u examples/basic/test.py
done

produces

$ ./venv2.8/bin/python -u examples/basic/test.py
Traceback (most recent call last):
  File "/Users/foo/Projects/jinja/examples/basic/test.py", line 26, in <module>
    tmpl = env.get_template("child.html")
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/environment.py", line 812, in get_template
    return self._load_template(name, self.make_globals(globals))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/environment.py", line 786, in _load_template
    template = self.loader.load(self, name, globals)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/loaders.py", line 125, in load
    code = environment.compile(source, name, filename)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/environment.py", line 565, in compile
    self.handle_exception(exc_info, source_hint=source_hint)
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/environment.py", line 754, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/_compat.py", line 37, in reraise
    raise value.with_traceback(tb)
  File "<unknown>", line 2, in <module>
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/environment.py", line 470, in _parse
    return Parser(self, source, name, encode_filename(filename)).parse()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/parser.py", line 897, in parse
    result = nodes.Template(self.subparse(), lineno=1)
                            ^^^^^^^^^^^^^^^
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/parser.py", line 884, in subparse
    self.stream.expect('block_end')
  File "/Users/foo/Projects/jinja/venv2.8/lib/python3.12/site-packages/jinja2/lexer.py", line 371, in expect
    raise TemplateSyntaxError("expected token %r, got %r" %
jinja2.exceptions.TemplateSyntaxError: expected token 'end of statement block', got '='

I found the seemingly relevant commit which discusses assigning include statements to a Name but due to the lack of a formal grammar (1194 👀) it's hard to know if this was missed in the actual tests, was supposed to work even back in 2.8, or just got overlooked during some refactoring

Environment:

• Python version: 3.12 (I can of course try with other versions but I don't believe this is relevant)
• Jinja versions: 2.8, 2.8.1, 2.9, 2.9.1, 2.9.2, 2.9.3, 2.9.4, 2.9.5, 2.9.6, 2.10, 2.10.1, 2.10.2, 2.10.3, 2.11.0, 2.11.1, 2.11.2, 2.11.3, 3.0.0, 3.0.1, 3.0.2, 3.0.3, 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.1.4

[JamesParrott]

Hi Matthew, great spot and nice work! I like the loop that tests against different versions of Jinja. I've reproduced it in Python3.13 and the latest Jinja.

I wonder if this is exactly what the "TemplateSyntaxError" would suggest - simply an instance of incorrect Jinja syntax (in code that's escaped testing).

For instance, in https://github.com/pallets/jinja/blob/main/examples/basic/test.py shouldn't:

{% include helpers = 'helpers.html' %}

Instead be:

{% import 'helpers.html' as helpers %}

Docs for convenience: https://jinja.palletsprojects.com/en/stable/templates/#include Import is just below Include.

After making that change, I actually get a different error, from another line that was added by the same commit you linked to. So perhaps this could've been better checked, as it contains erroneous Jinja code.

python examples\basic\test.py
Traceback (most recent call last):
  File "%CD%\jinja\examples\basic\test.py", line 28, in <module>
    tmpl = env.get_template("child.html")
  File "%CD%\jinja\src\jinja2\environment.py", line 1015, in get_template
    return self._load_template(name, globals)
           ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "%CD%\jinja\src\jinja2\environment.py", line 974, in _load_template
    template = self.loader.load(self, name, self.make_globals(globals))
  File "%CD%\jinja\src\jinja2\loaders.py", line 138, in load
    code = environment.compile(source, name, filename)
  File "%CD%\jinja\src\jinja2\environment.py", line 770, in compile
    self.handle_exception(source=source_hint)
    ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "%CD%\jinja\src\jinja2\environment.py", line 941, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "<unknown>", line 4, in template
jinja2.exceptions.TemplateSyntaxError: Encountered unknown tag 'title'.

I did not find anything in the docs for a "title" block. But there is a variable named "title", referred to in the default.html that child.html extends. So after:

Replacing

{% title = 'Hello World' %}

with

{% set title = 'Hello World' %}

this is the result:

(jinja2) %CD%\jinja>python examples\basic\test.py
<!doctype html>
<title>Hello World</title>

    42
    23