# -*- coding: utf-8 -*- # There are tests here with unicode string literals and # identifiers. There's a code in ast.c that was added because of a # failure with a non-ascii-only expression. So, I have tests for # that. There are workarounds that would let me run tests for that # code without unicode identifiers and strings, but just using them # directly seems like the easiest and therefore safest thing to do. # Unicode identifiers in tests is allowed by PEP 3131. import ast import os import re import types import decimal import unittest import warnings from test import support from test.support.os_helper import temp_cwd from test.support.script_helper import assert_python_failure, assert_python_ok a_global = 'global variable' # You could argue that I'm too strict in looking for specific error # values with assertRaisesRegex, but without it it's way too easy to # make a syntax error in the test strings. Especially with all of the # triple quotes, raw strings, backslashes, etc. I think it's a # worthwhile tradeoff. When I switched to this method, I found many # examples where I wasn't testing what I thought I was. class TestCase(unittest.TestCase): def assertAllRaise(self, exception_type, regex, error_strings): for str in error_strings: with self.subTest(str=str): with self.assertRaisesRegex(exception_type, regex): eval(str) def test__format__lookup(self): # Make sure __format__ is looked up on the type, not the instance. class X: def __format__(self, spec): return 'class' x = X() # Add a bound __format__ method to the 'y' instance, but not # the 'x' instance. y = X() y.__format__ = types.MethodType(lambda self, spec: 'instance', y) self.assertEqual(f'{y}', format(y)) self.assertEqual(f'{y}', 'class') self.assertEqual(format(x), format(y)) # __format__ is not called this way, but still make sure it # returns what we expect (so we can make sure we're bypassing # it). self.assertEqual(x.__format__(''), 'class') self.assertEqual(y.__format__(''), 'instance') # This is how __format__ is actually called. self.assertEqual(type(x).__format__(x, ''), 'class') self.assertEqual(type(y).__format__(y, ''), 'class') def test_ast(self): # Inspired by http://bugs.python.org/issue24975 class X: def __init__(self): self.called = False def __call__(self): self.called = True return 4 x = X() expr = """ a = 10 f'{a * x()}'""" t = ast.parse(expr) c = compile(t, '', 'exec') # Make sure x was not called. self.assertFalse(x.called) # Actually run the code. exec(c) # Make sure x was called. self.assertTrue(x.called) def test_ast_line_numbers(self): expr = """ a = 10 f'{a * x()}'""" t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) # check `a = 10` self.assertEqual(type(t.body[0]), ast.Assign) self.assertEqual(t.body[0].lineno, 2) # check `f'...'` self.assertEqual(type(t.body[1]), ast.Expr) self.assertEqual(type(t.body[1].value), ast.JoinedStr) self.assertEqual(len(t.body[1].value.values), 1) self.assertEqual(type(t.body[1].value.values[0]), ast.FormattedValue) self.assertEqual(t.body[1].lineno, 3) self.assertEqual(t.body[1].value.lineno, 3) self.assertEqual(t.body[1].value.values[0].lineno, 3) # check the binop location binop = t.body[1].value.values[0].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.Call) self.assertEqual(binop.lineno, 3) self.assertEqual(binop.left.lineno, 3) self.assertEqual(binop.right.lineno, 3) self.assertEqual(binop.col_offset, 3) self.assertEqual(binop.left.col_offset, 3) self.assertEqual(binop.right.col_offset, 7) def test_ast_line_numbers_multiple_formattedvalues(self): expr = """ f'no formatted values' f'eggs {a * x()} spam {b + y()}'""" t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) # check `f'no formatted value'` self.assertEqual(type(t.body[0]), ast.Expr) self.assertEqual(type(t.body[0].value), ast.JoinedStr) self.assertEqual(t.body[0].lineno, 2) # check `f'...'` self.assertEqual(type(t.body[1]), ast.Expr) self.assertEqual(type(t.body[1].value), ast.JoinedStr) self.assertEqual(len(t.body[1].value.values), 4) self.assertEqual(type(t.body[1].value.values[0]), ast.Constant) self.assertEqual(type(t.body[1].value.values[0].value), str) self.assertEqual(type(t.body[1].value.values[1]), ast.FormattedValue) self.assertEqual(type(t.body[1].value.values[2]), ast.Constant) self.assertEqual(type(t.body[1].value.values[2].value), str) self.assertEqual(type(t.body[1].value.values[3]), ast.FormattedValue) self.assertEqual(t.body[1].lineno, 3) self.assertEqual(t.body[1].value.lineno, 3) self.assertEqual(t.body[1].value.values[0].lineno, 3) self.assertEqual(t.body[1].value.values[1].lineno, 3) self.assertEqual(t.body[1].value.values[2].lineno, 3) self.assertEqual(t.body[1].value.values[3].lineno, 3) # check the first binop location binop1 = t.body[1].value.values[1].value self.assertEqual(type(binop1), ast.BinOp) self.assertEqual(type(binop1.left), ast.Name) self.assertEqual(type(binop1.op), ast.Mult) self.assertEqual(type(binop1.right), ast.Call) self.assertEqual(binop1.lineno, 3) self.assertEqual(binop1.left.lineno, 3) self.assertEqual(binop1.right.lineno, 3) self.assertEqual(binop1.col_offset, 8) self.assertEqual(binop1.left.col_offset, 8) self.assertEqual(binop1.right.col_offset, 12) # check the second binop location binop2 = t.body[1].value.values[3].value self.assertEqual(type(binop2), ast.BinOp) self.assertEqual(type(binop2.left), ast.Name) self.assertEqual(type(binop2.op), ast.Add) self.assertEqual(type(binop2.right), ast.Call) self.assertEqual(binop2.lineno, 3) self.assertEqual(binop2.left.lineno, 3) self.assertEqual(binop2.right.lineno, 3) self.assertEqual(binop2.col_offset, 23) self.assertEqual(binop2.left.col_offset, 23) self.assertEqual(binop2.right.col_offset, 27) def test_ast_line_numbers_nested(self): expr = """ a = 10 f'{a * f"-{x()}-"}'""" t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) # check `a = 10` self.assertEqual(type(t.body[0]), ast.Assign) self.assertEqual(t.body[0].lineno, 2) # check `f'...'` self.assertEqual(type(t.body[1]), ast.Expr) self.assertEqual(type(t.body[1].value), ast.JoinedStr) self.assertEqual(len(t.body[1].value.values), 1) self.assertEqual(type(t.body[1].value.values[0]), ast.FormattedValue) self.assertEqual(t.body[1].lineno, 3) self.assertEqual(t.body[1].value.lineno, 3) self.assertEqual(t.body[1].value.values[0].lineno, 3) # check the binop location binop = t.body[1].value.values[0].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.JoinedStr) self.assertEqual(binop.lineno, 3) self.assertEqual(binop.left.lineno, 3) self.assertEqual(binop.right.lineno, 3) self.assertEqual(binop.col_offset, 3) self.assertEqual(binop.left.col_offset, 3) self.assertEqual(binop.right.col_offset, 7) # check the nested call location self.assertEqual(len(binop.right.values), 3) self.assertEqual(type(binop.right.values[0]), ast.Constant) self.assertEqual(type(binop.right.values[0].value), str) self.assertEqual(type(binop.right.values[1]), ast.FormattedValue) self.assertEqual(type(binop.right.values[2]), ast.Constant) self.assertEqual(type(binop.right.values[2].value), str) self.assertEqual(binop.right.values[0].lineno, 3) self.assertEqual(binop.right.values[1].lineno, 3) self.assertEqual(binop.right.values[2].lineno, 3) call = binop.right.values[1].value self.assertEqual(type(call), ast.Call) self.assertEqual(call.lineno, 3) self.assertEqual(call.col_offset, 11) def test_ast_line_numbers_duplicate_expression(self): expr = """ a = 10 f'{a * x()} {a * x()} {a * x()}' """ t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) # check `a = 10` self.assertEqual(type(t.body[0]), ast.Assign) self.assertEqual(t.body[0].lineno, 2) # check `f'...'` self.assertEqual(type(t.body[1]), ast.Expr) self.assertEqual(type(t.body[1].value), ast.JoinedStr) self.assertEqual(len(t.body[1].value.values), 5) self.assertEqual(type(t.body[1].value.values[0]), ast.FormattedValue) self.assertEqual(type(t.body[1].value.values[1]), ast.Constant) self.assertEqual(type(t.body[1].value.values[1].value), str) self.assertEqual(type(t.body[1].value.values[2]), ast.FormattedValue) self.assertEqual(type(t.body[1].value.values[3]), ast.Constant) self.assertEqual(type(t.body[1].value.values[3].value), str) self.assertEqual(type(t.body[1].value.values[4]), ast.FormattedValue) self.assertEqual(t.body[1].lineno, 3) self.assertEqual(t.body[1].value.lineno, 3) self.assertEqual(t.body[1].value.values[0].lineno, 3) self.assertEqual(t.body[1].value.values[1].lineno, 3) self.assertEqual(t.body[1].value.values[2].lineno, 3) self.assertEqual(t.body[1].value.values[3].lineno, 3) self.assertEqual(t.body[1].value.values[4].lineno, 3) # check the first binop location binop = t.body[1].value.values[0].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.Call) self.assertEqual(binop.lineno, 3) self.assertEqual(binop.left.lineno, 3) self.assertEqual(binop.right.lineno, 3) self.assertEqual(binop.col_offset, 3) self.assertEqual(binop.left.col_offset, 3) self.assertEqual(binop.right.col_offset, 7) # check the second binop location binop = t.body[1].value.values[2].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.Call) self.assertEqual(binop.lineno, 3) self.assertEqual(binop.left.lineno, 3) self.assertEqual(binop.right.lineno, 3) self.assertEqual(binop.col_offset, 13) self.assertEqual(binop.left.col_offset, 13) self.assertEqual(binop.right.col_offset, 17) # check the third binop location binop = t.body[1].value.values[4].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.Call) self.assertEqual(binop.lineno, 3) self.assertEqual(binop.left.lineno, 3) self.assertEqual(binop.right.lineno, 3) self.assertEqual(binop.col_offset, 23) self.assertEqual(binop.left.col_offset, 23) self.assertEqual(binop.right.col_offset, 27) def test_ast_numbers_fstring_with_formatting(self): t = ast.parse('f"Here is that pesky {xxx:.3f} again"') self.assertEqual(len(t.body), 1) self.assertEqual(t.body[0].lineno, 1) self.assertEqual(type(t.body[0]), ast.Expr) self.assertEqual(type(t.body[0].value), ast.JoinedStr) self.assertEqual(len(t.body[0].value.values), 3) self.assertEqual(type(t.body[0].value.values[0]), ast.Constant) self.assertEqual(type(t.body[0].value.values[1]), ast.FormattedValue) self.assertEqual(type(t.body[0].value.values[2]), ast.Constant) _, expr, _ = t.body[0].value.values name = expr.value self.assertEqual(type(name), ast.Name) self.assertEqual(name.lineno, 1) self.assertEqual(name.end_lineno, 1) self.assertEqual(name.col_offset, 22) self.assertEqual(name.end_col_offset, 25) def test_ast_line_numbers_multiline_fstring(self): # See bpo-30465 for details. expr = """ a = 10 f''' {a * x()} non-important content ''' """ t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) # check `a = 10` self.assertEqual(type(t.body[0]), ast.Assign) self.assertEqual(t.body[0].lineno, 2) # check `f'...'` self.assertEqual(type(t.body[1]), ast.Expr) self.assertEqual(type(t.body[1].value), ast.JoinedStr) self.assertEqual(len(t.body[1].value.values), 3) self.assertEqual(type(t.body[1].value.values[0]), ast.Constant) self.assertEqual(type(t.body[1].value.values[0].value), str) self.assertEqual(type(t.body[1].value.values[1]), ast.FormattedValue) self.assertEqual(type(t.body[1].value.values[2]), ast.Constant) self.assertEqual(type(t.body[1].value.values[2].value), str) self.assertEqual(t.body[1].lineno, 3) self.assertEqual(t.body[1].value.lineno, 3) self.assertEqual(t.body[1].value.values[0].lineno, 3) self.assertEqual(t.body[1].value.values[1].lineno, 4) self.assertEqual(t.body[1].value.values[2].lineno, 6) self.assertEqual(t.body[1].col_offset, 0) self.assertEqual(t.body[1].value.col_offset, 0) self.assertEqual(t.body[1].value.values[0].col_offset, 4) self.assertEqual(t.body[1].value.values[1].col_offset, 2) self.assertEqual(t.body[1].value.values[2].col_offset, 11) # NOTE: the following lineno information and col_offset is correct for # expressions within FormattedValues. binop = t.body[1].value.values[1].value self.assertEqual(type(binop), ast.BinOp) self.assertEqual(type(binop.left), ast.Name) self.assertEqual(type(binop.op), ast.Mult) self.assertEqual(type(binop.right), ast.Call) self.assertEqual(binop.lineno, 4) self.assertEqual(binop.left.lineno, 4) self.assertEqual(binop.right.lineno, 6) self.assertEqual(binop.col_offset, 3) self.assertEqual(binop.left.col_offset, 3) self.assertEqual(binop.right.col_offset, 7) expr = """ a = f''' {blech} ''' """ t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 1) # Check f'...' self.assertEqual(type(t.body[0]), ast.Assign) self.assertEqual(type(t.body[0].value), ast.JoinedStr) self.assertEqual(len(t.body[0].value.values), 3) self.assertEqual(type(t.body[0].value.values[1]), ast.FormattedValue) self.assertEqual(t.body[0].lineno, 2) self.assertEqual(t.body[0].value.lineno, 2) self.assertEqual(t.body[0].value.values[0].lineno, 2) self.assertEqual(t.body[0].value.values[1].lineno, 3) self.assertEqual(t.body[0].value.values[2].lineno, 3) self.assertEqual(t.body[0].col_offset, 0) self.assertEqual(t.body[0].value.col_offset, 4) self.assertEqual(t.body[0].value.values[0].col_offset, 8) self.assertEqual(t.body[0].value.values[1].col_offset, 10) self.assertEqual(t.body[0].value.values[2].col_offset, 17) # Check {blech} self.assertEqual(t.body[0].value.values[1].value.lineno, 3) self.assertEqual(t.body[0].value.values[1].value.end_lineno, 3) self.assertEqual(t.body[0].value.values[1].value.col_offset, 11) self.assertEqual(t.body[0].value.values[1].value.end_col_offset, 16) def test_ast_line_numbers_with_parentheses(self): expr = """ x = ( f" {test(t)}" )""" t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 1) # check the joinedstr location joinedstr = t.body[0].value self.assertEqual(type(joinedstr), ast.JoinedStr) self.assertEqual(joinedstr.lineno, 3) self.assertEqual(joinedstr.end_lineno, 3) self.assertEqual(joinedstr.col_offset, 4) self.assertEqual(joinedstr.end_col_offset, 17) # check the formatted value location fv = t.body[0].value.values[1] self.assertEqual(type(fv), ast.FormattedValue) self.assertEqual(fv.lineno, 3) self.assertEqual(fv.end_lineno, 3) self.assertEqual(fv.col_offset, 7) self.assertEqual(fv.end_col_offset, 16) # check the test(t) location call = t.body[0].value.values[1].value self.assertEqual(type(call), ast.Call) self.assertEqual(call.lineno, 3) self.assertEqual(call.end_lineno, 3) self.assertEqual(call.col_offset, 8) self.assertEqual(call.end_col_offset, 15) expr = """ x = ( u'wat', u"wat", b'wat', b"wat", f'wat', f"wat", ) y = ( u'''wat''', u\"\"\"wat\"\"\", b'''wat''', b\"\"\"wat\"\"\", f'''wat''', f\"\"\"wat\"\"\", ) """ t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 2) x, y = t.body # Check the single quoted string offsets first. offsets = [ (elt.col_offset, elt.end_col_offset) for elt in x.value.elts ] self.assertTrue(all( offset == (4, 10) for offset in offsets )) # Check the triple quoted string offsets. offsets = [ (elt.col_offset, elt.end_col_offset) for elt in y.value.elts ] self.assertTrue(all( offset == (4, 14) for offset in offsets )) expr = """ x = ( 'PERL_MM_OPT', ( f'wat' f'some_string={f(x)} ' f'wat' ), ) """ t = ast.parse(expr) self.assertEqual(type(t), ast.Module) self.assertEqual(len(t.body), 1) # check the fstring fstring = t.body[0].value.elts[1] self.assertEqual(type(fstring), ast.JoinedStr) self.assertEqual(len(fstring.values), 3) wat1, middle, wat2 = fstring.values # check the first wat self.assertEqual(type(wat1), ast.Constant) self.assertEqual(wat1.lineno, 4) self.assertEqual(wat1.end_lineno, 5) self.assertEqual(wat1.col_offset, 14) self.assertEqual(wat1.end_col_offset, 26) # check the call call = middle.value self.assertEqual(type(call), ast.Call) self.assertEqual(call.lineno, 5) self.assertEqual(call.end_lineno, 5) self.assertEqual(call.col_offset, 27) self.assertEqual(call.end_col_offset, 31) # check the second wat self.assertEqual(type(wat2), ast.Constant) self.assertEqual(wat2.lineno, 5) self.assertEqual(wat2.end_lineno, 6) self.assertEqual(wat2.col_offset, 32) # wat ends at the offset 17, but the whole f-string # ends at the offset 18 (since the quote is part of the # f-string but not the wat string) self.assertEqual(wat2.end_col_offset, 17) self.assertEqual(fstring.end_col_offset, 18) def test_ast_fstring_empty_format_spec(self): expr = "f'{expr:}'" mod = ast.parse(expr) self.assertEqual(type(mod), ast.Module) self.assertEqual(len(mod.body), 1) fstring = mod.body[0].value self.assertEqual(type(fstring), ast.JoinedStr) self.assertEqual(len(fstring.values), 1) fv = fstring.values[0] self.assertEqual(type(fv), ast.FormattedValue) format_spec = fv.format_spec self.assertEqual(type(format_spec), ast.JoinedStr) self.assertEqual(len(format_spec.values), 0) def test_docstring(self): def f(): f'''Not a docstring''' self.assertIsNone(f.__doc__) def g(): '''Not a docstring''' \ f'' self.assertIsNone(g.__doc__) def test_literal_eval(self): with self.assertRaisesRegex(ValueError, 'malformed node or string'): ast.literal_eval("f'x'") def test_ast_compile_time_concat(self): x = [''] expr = """x[0] = 'foo' f'{3}'""" t = ast.parse(expr) c = compile(t, '', 'exec') exec(c) self.assertEqual(x[0], 'foo3') def test_compile_time_concat_errors(self): self.assertAllRaise(SyntaxError, 'cannot mix bytes and nonbytes literals', [r"""f'' b''""", r"""b'' f''""", ]) def test_literal(self): self.assertEqual(f'', '') self.assertEqual(f'a', 'a') self.assertEqual(f' ', ' ') def test_unterminated_string(self): self.assertAllRaise(SyntaxError, 'unterminated string', [r"""f'{"x'""", r"""f'{"x}'""", r"""f'{("x'""", r"""f'{("x}'""", ]) @unittest.skipIf(support.is_wasi, "exhausts limited stack on WASI") def test_mismatched_parens(self): self.assertAllRaise(SyntaxError, r"closing parenthesis '\}' " r"does not match opening parenthesis '\('", ["f'{((}'", ]) self.assertAllRaise(SyntaxError, r"closing parenthesis '\)' " r"does not match opening parenthesis '\['", ["f'{a[4)}'", ]) self.assertAllRaise(SyntaxError, r"closing parenthesis '\]' " r"does not match opening parenthesis '\('", ["f'{a(4]}'", ]) self.assertAllRaise(SyntaxError, r"closing parenthesis '\}' " r"does not match opening parenthesis '\['", ["f'{a[4}'", ]) self.assertAllRaise(SyntaxError, r"closing parenthesis '\}' " r"does not match opening parenthesis '\('", ["f'{a(4}'", ]) self.assertRaises(SyntaxError, eval, "f'{" + "("*500 + "}'") @unittest.skipIf(support.is_wasi, "exhausts limited stack on WASI") def test_fstring_nested_too_deeply(self): self.assertAllRaise(SyntaxError, "f-string: expressions nested too deeply", ['f"{1+2:{1+2:{1+1:{1}}}}"']) def create_nested_fstring(n): if n == 0: return "1+1" prev = create_nested_fstring(n-1) return f'f"{{{prev}}}"' self.assertAllRaise(SyntaxError, "too many nested f-strings", [create_nested_fstring(160)]) def test_syntax_error_in_nested_fstring(self): # See gh-104016 for more information on this crash self.assertAllRaise(SyntaxError, "invalid syntax", ['f"{1 1:' + ('{f"1:' * 199)]) def test_double_braces(self): self.assertEqual(f'{{', '{') self.assertEqual(f'a{{', 'a{') self.assertEqual(f'{{b', '{b') self.assertEqual(f'a{{b', 'a{b') self.assertEqual(f'}}', '}') self.assertEqual(f'a}}', 'a}') self.assertEqual(f'}}b', '}b') self.assertEqual(f'a}}b', 'a}b') self.assertEqual(f'{{}}', '{}') self.assertEqual(f'a{{}}', 'a{}') self.assertEqual(f'{{b}}', '{b}') self.assertEqual(f'{{}}c', '{}c') self.assertEqual(f'a{{b}}', 'a{b}') self.assertEqual(f'a{{}}c', 'a{}c') self.assertEqual(f'{{b}}c', '{b}c') self.assertEqual(f'a{{b}}c', 'a{b}c') self.assertEqual(f'{{{10}', '{10') self.assertEqual(f'}}{10}', '}10') self.assertEqual(f'}}{{{10}', '}{10') self.assertEqual(f'}}a{{{10}', '}a{10') self.assertEqual(f'{10}{{', '10{') self.assertEqual(f'{10}}}', '10}') self.assertEqual(f'{10}}}{{', '10}{') self.assertEqual(f'{10}}}a{{' '}', '10}a{}') # Inside of strings, don't interpret doubled brackets. self.assertEqual(f'{"{{}}"}', '{{}}') self.assertAllRaise(TypeError, 'unhashable type', ["f'{ {{}} }'", # dict in a set ]) def test_compile_time_concat(self): x = 'def' self.assertEqual('abc' f'## {x}ghi', 'abc## defghi') self.assertEqual('abc' f'{x}' 'ghi', 'abcdefghi') self.assertEqual('abc' f'{x}' 'gh' f'i{x:4}', 'abcdefghidef ') self.assertEqual('{x}' f'{x}', '{x}def') self.assertEqual('{x' f'{x}', '{xdef') self.assertEqual('{x}' f'{x}', '{x}def') self.assertEqual('{{x}}' f'{x}', '{{x}}def') self.assertEqual('{{x' f'{x}', '{{xdef') self.assertEqual('x}}' f'{x}', 'x}}def') self.assertEqual(f'{x}' 'x}}', 'defx}}') self.assertEqual(f'{x}' '', 'def') self.assertEqual('' f'{x}' '', 'def') self.assertEqual('' f'{x}', 'def') self.assertEqual(f'{x}' '2', 'def2') self.assertEqual('1' f'{x}' '2', '1def2') self.assertEqual('1' f'{x}', '1def') self.assertEqual(f'{x}' f'-{x}', 'def-def') self.assertEqual('' f'', '') self.assertEqual('' f'' '', '') self.assertEqual('' f'' '' f'', '') self.assertEqual(f'', '') self.assertEqual(f'' '', '') self.assertEqual(f'' '' f'', '') self.assertEqual(f'' '' f'' '', '') # This is not really [f'{'] + [f'}'] since we treat the inside # of braces as a purely new context, so it is actually f'{ and # then eval(' f') (a valid expression) and then }' which would # constitute a valid f-string. self.assertEqual(f'{' f'}', ' f') self.assertAllRaise(SyntaxError, "expecting '}'", ['''f'{3' f"}"''', # can't concat to get a valid f-string ]) def test_comments(self): # These aren't comments, since they're in strings. d = {'#': 'hash'} self.assertEqual(f'{"#"}', '#') self.assertEqual(f'{d["#"]}', 'hash') self.assertAllRaise(SyntaxError, "'{' was never closed", ["f'{1#}'", # error because everything after '#' is a comment "f'{#}'", "f'one: {1#}'", "f'{1# one} {2 this is a comment still#}'", ]) self.assertAllRaise(SyntaxError, r"f-string: unmatched '\)'", ["f'{)#}'", # When wrapped in parens, this becomes # '()#)'. Make sure that doesn't compile. ]) self.assertEqual(f'''A complex trick: { 2 # two }''', 'A complex trick: 2') self.assertEqual(f''' { 40 # fourty + # plus 2 # two }''', '\n42') self.assertEqual(f''' { 40 # fourty + # plus 2 # two }''', '\n42') self.assertEqual(f''' # this is not a comment { # the following operation it's 3 # this is a number * 2}''', '\n# this is not a comment\n6') self.assertEqual(f''' {# f'a {comment}' 86 # constant # nothing more }''', '\n86') self.assertAllRaise(SyntaxError, r"f-string: valid expression required before '}'", ["""f''' { # only a comment }''' """, # this is equivalent to f'{}' ]) def test_many_expressions(self): # Create a string with many expressions in it. Note that # because we have a space in here as a literal, we're actually # going to use twice as many ast nodes: one for each literal # plus one for each expression. def build_fstr(n, extra=''): return "f'" + ('{x} ' * n) + extra + "'" x = 'X' width = 1 # Test around 256. for i in range(250, 260): self.assertEqual(eval(build_fstr(i)), (x+' ')*i) # Test concatenating 2 largs fstrings. self.assertEqual(eval(build_fstr(255)*256), (x+' ')*(255*256)) s = build_fstr(253, '{x:{width}} ') self.assertEqual(eval(s), (x+' ')*254) # Test lots of expressions and constants, concatenated. s = "f'{1}' 'x' 'y'" * 1024 self.assertEqual(eval(s), '1xy' * 1024) def test_format_specifier_expressions(self): width = 10 precision = 4 value = decimal.Decimal('12.34567') self.assertEqual(f'result: {value:{width}.{precision}}', 'result: 12.35') self.assertEqual(f'result: {value:{width!r}.{precision}}', 'result: 12.35') self.assertEqual(f'result: {value:{width:0}.{precision:1}}', 'result: 12.35') self.assertEqual(f'result: {value:{1}{0:0}.{precision:1}}', 'result: 12.35') self.assertEqual(f'result: {value:{ 1}{ 0:0}.{ precision:1}}', 'result: 12.35') self.assertEqual(f'{10:#{1}0x}', ' 0xa') self.assertEqual(f'{10:{"#"}1{0}{"x"}}', ' 0xa') self.assertEqual(f'{-10:-{"#"}1{0}x}', ' -0xa') self.assertEqual(f'{-10:{"-"}#{1}0{"x"}}', ' -0xa') self.assertEqual(f'{10:#{3 != {4:5} and width}x}', ' 0xa') self.assertEqual(f'result: {value:{width:{0}}.{precision:1}}', 'result: 12.35') self.assertAllRaise(SyntaxError, "f-string: expecting ':' or '}'", ["""f'{"s"!r{":10"}}'""", # This looks like a nested format spec. ]) self.assertAllRaise(SyntaxError, "f-string: expecting a valid expression after '{'", [# Invalid syntax inside a nested spec. "f'{4:{/5}}'", ]) self.assertAllRaise(SyntaxError, 'f-string: invalid conversion character', [# No expansion inside conversion or for # the : or ! itself. """f'{"s"!{"r"}}'""", ]) def test_custom_format_specifier(self): class CustomFormat: def __format__(self, format_spec): return format_spec self.assertEqual(f'{CustomFormat():\n}', '\n') self.assertEqual(f'{CustomFormat():\u2603}', '☃') with self.assertWarns(SyntaxWarning): exec(r'f"{F():¯\_(ツ)_/¯}"', {'F': CustomFormat}) def test_side_effect_order(self): class X: def __init__(self): self.i = 0 def __format__(self, spec): self.i += 1 return str(self.i) x = X() self.assertEqual(f'{x} {x}', '1 2') def test_missing_expression(self): self.assertAllRaise(SyntaxError, "f-string: valid expression required before '}'", ["f'{}'", "f'{ }'" "f' {} '", "f'{10:{ }}'", "f' { } '", # The Python parser ignores also the following # whitespace characters in additional to a space. "f'''{\t\f\r\n}'''", ]) self.assertAllRaise(SyntaxError, "f-string: valid expression required before '!'", ["f'{!r}'", "f'{ !r}'", "f'{!}'", "f'''{\t\f\r\n!a}'''", # Catch empty expression before the # missing closing brace. "f'{!'", "f'{!s:'", # Catch empty expression before the # invalid conversion. "f'{!x}'", "f'{ !xr}'", "f'{!x:}'", "f'{!x:a}'", "f'{ !xr:}'", "f'{ !xr:a}'", ]) self.assertAllRaise(SyntaxError, "f-string: valid expression required before ':'", ["f'{:}'", "f'{ :!}'", "f'{:2}'", "f'''{\t\f\r\n:a}'''", "f'{:'", ]) self.assertAllRaise(SyntaxError, "f-string: valid expression required before '='", ["f'{=}'", "f'{ =}'", "f'{ =:}'", "f'{ =!}'", "f'''{\t\f\r\n=}'''", "f'{='", ]) # Different error message is raised for other whitespace characters. self.assertAllRaise(SyntaxError, r"invalid non-printable character U\+00A0", ["f'''{\xa0}'''", "\xa0", ]) def test_parens_in_expressions(self): self.assertEqual(f'{3,}', '(3,)') self.assertAllRaise(SyntaxError, "f-string: expecting a valid expression after '{'", ["f'{,}'", ]) self.assertAllRaise(SyntaxError, r"f-string: unmatched '\)'", ["f'{3)+(4}'", ]) def test_newlines_before_syntax_error(self): self.assertAllRaise(SyntaxError, "f-string: expecting a valid expression after '{'", ["f'{.}'", "\nf'{.}'", "\n\nf'{.}'"]) def test_backslashes_in_string_part(self): self.assertEqual(f'\t', '\t') self.assertEqual(r'\t', '\\t') self.assertEqual(rf'\t', '\\t') self.assertEqual(f'{2}\t', '2\t') self.assertEqual(f'{2}\t{3}', '2\t3') self.assertEqual(f'\t{3}', '\t3') self.assertEqual(f'\u0394', '\u0394') self.assertEqual(r'\u0394', '\\u0394') self.assertEqual(rf'\u0394', '\\u0394') self.assertEqual(f'{2}\u0394', '2\u0394') self.assertEqual(f'{2}\u0394{3}', '2\u03943') self.assertEqual(f'\u0394{3}', '\u03943') self.assertEqual(f'\U00000394', '\u0394') self.assertEqual(r'\U00000394', '\\U00000394') self.assertEqual(rf'\U00000394', '\\U00000394') self.assertEqual(f'{2}\U00000394', '2\u0394') self.assertEqual(f'{2}\U00000394{3}', '2\u03943') self.assertEqual(f'\U00000394{3}', '\u03943') self.assertEqual(f'\N{GREEK CAPITAL LETTER DELTA}', '\u0394') self.assertEqual(f'{2}\N{GREEK CAPITAL LETTER DELTA}', '2\u0394') self.assertEqual(f'{2}\N{GREEK CAPITAL LETTER DELTA}{3}', '2\u03943') self.assertEqual(f'\N{GREEK CAPITAL LETTER DELTA}{3}', '\u03943') self.assertEqual(f'2\N{GREEK CAPITAL LETTER DELTA}', '2\u0394') self.assertEqual(f'2\N{GREEK CAPITAL LETTER DELTA}3', '2\u03943') self.assertEqual(f'\N{GREEK CAPITAL LETTER DELTA}3', '\u03943') self.assertEqual(f'\x20', ' ') self.assertEqual(r'\x20', '\\x20') self.assertEqual(rf'\x20', '\\x20') self.assertEqual(f'{2}\x20', '2 ') self.assertEqual(f'{2}\x20{3}', '2 3') self.assertEqual(f'\x20{3}', ' 3') self.assertEqual(f'2\x20', '2 ') self.assertEqual(f'2\x203', '2 3') self.assertEqual(f'\x203', ' 3') with self.assertWarns(SyntaxWarning): # invalid escape sequence value = eval(r"f'\{6*7}'") self.assertEqual(value, '\\42') with self.assertWarns(SyntaxWarning): # invalid escape sequence value = eval(r"f'\g'") self.assertEqual(value, '\\g') self.assertEqual(f'\\{6*7}', '\\42') self.assertEqual(fr'\{6*7}', '\\42') AMPERSAND = 'spam' # Get the right unicode character (&), or pick up local variable # depending on the number of backslashes. self.assertEqual(f'\N{AMPERSAND}', '&') self.assertEqual(f'\\N{AMPERSAND}', '\\Nspam') self.assertEqual(fr'\N{AMPERSAND}', '\\Nspam') self.assertEqual(f'\\\N{AMPERSAND}', '\\&') def test_misformed_unicode_character_name(self): # These test are needed because unicode names are parsed # differently inside f-strings. self.assertAllRaise(SyntaxError, r"\(unicode error\) 'unicodeescape' codec can't decode bytes in position .*: malformed \\N character escape", [r"f'\N'", r"f'\N '", r"f'\N '", # See bpo-46503. r"f'\N{'", r"f'\N{GREEK CAPITAL LETTER DELTA'", # Here are the non-f-string versions, # which should give the same errors. r"'\N'", r"'\N '", r"'\N '", r"'\N{'", r"'\N{GREEK CAPITAL LETTER DELTA'", ]) def test_backslashes_in_expression_part(self): self.assertEqual(f"{( 1 + 2 )}", "3") self.assertEqual("\N{LEFT CURLY BRACKET}", '{') self.assertEqual(f'{"\N{LEFT CURLY BRACKET}"}', '{') self.assertEqual(rf'{"\N{LEFT CURLY BRACKET}"}', '{') self.assertAllRaise(SyntaxError, "f-string: valid expression required before '}'", ["f'{\n}'", ]) def test_invalid_backslashes_inside_fstring_context(self): # All of these variations are invalid python syntax, # so they are also invalid in f-strings as well. cases = [ formatting.format(expr=expr) for formatting in [ "{expr}", "f'{{{expr}}}'", "rf'{{{expr}}}'", ] for expr in [ r"\'a\'", r"\t3", r"\\"[0], ] ] self.assertAllRaise(SyntaxError, 'unexpected character after line continuation', cases) def test_no_escapes_for_braces(self): """ Only literal curly braces begin an expression. """ # \x7b is '{'. self.assertEqual(f'\x7b1+1}}', '{1+1}') self.assertEqual(f'\x7b1+1', '{1+1') self.assertEqual(f'\u007b1+1', '{1+1') self.assertEqual(f'\N{LEFT CURLY BRACKET}1+1\N{RIGHT CURLY BRACKET}', '{1+1}') def test_newlines_in_expressions(self): self.assertEqual(f'{0}', '0') self.assertEqual(rf'''{3+ 4}''', '7') def test_lambda(self): x = 5 self.assertEqual(f'{(lambda y:x*y)("8")!r}', "'88888'") self.assertEqual(f'{(lambda y:x*y)("8")!r:10}', "'88888' ") self.assertEqual(f'{(lambda y:x*y)("8"):10}', "88888 ") # lambda doesn't work without parens, because the colon # makes the parser think it's a format_spec # emit warning if we can match a format_spec self.assertAllRaise(SyntaxError, "f-string: lambda expressions are not allowed " "without parentheses", ["f'{lambda x:x}'", "f'{lambda :x}'", "f'{lambda *arg, :x}'", "f'{1, lambda:x}'", "f'{lambda x:}'", "f'{lambda :}'", ]) # Ensure the detection of invalid lambdas doesn't trigger detection # for valid lambdas in the second error pass with self.assertRaisesRegex(SyntaxError, "invalid syntax"): compile("lambda name_3=f'{name_4}': {name_3}\n1 $ 1", "", "exec") # but don't emit the paren warning in general cases with self.assertRaisesRegex(SyntaxError, "f-string: expecting a valid expression after '{'"): eval("f'{+ lambda:None}'") def test_valid_prefixes(self): self.assertEqual(F'{1}', "1") self.assertEqual(FR'{2}', "2") self.assertEqual(fR'{3}', "3") def test_roundtrip_raw_quotes(self): self.assertEqual(fr"\'", "\\'") self.assertEqual(fr'\"', '\\"') self.assertEqual(fr'\"\'', '\\"\\\'') self.assertEqual(fr'\'\"', '\\\'\\"') self.assertEqual(fr'\"\'\"', '\\"\\\'\\"') self.assertEqual(fr'\'\"\'', '\\\'\\"\\\'') self.assertEqual(fr'\"\'\"\'', '\\"\\\'\\"\\\'') def test_fstring_backslash_before_double_bracket(self): deprecated_cases = [ (r"f'\{{\}}'", '\\{\\}'), (r"f'\{{'", '\\{'), (r"f'\{{{1+1}'", '\\{2'), (r"f'\}}{1+1}'", '\\}2'), (r"f'{1+1}\}}'", '2\\}') ] for case, expected_result in deprecated_cases: with self.subTest(case=case, expected_result=expected_result): with self.assertWarns(SyntaxWarning): result = eval(case) self.assertEqual(result, expected_result) self.assertEqual(fr'\{{\}}', '\\{\\}') self.assertEqual(fr'\{{', '\\{') self.assertEqual(fr'\{{{1+1}', '\\{2') self.assertEqual(fr'\}}{1+1}', '\\}2') self.assertEqual(fr'{1+1}\}}', '2\\}') def test_fstring_backslash_before_double_bracket_warns_once(self): with self.assertWarns(SyntaxWarning) as w: eval(r"f'\{{'") self.assertEqual(len(w.warnings), 1) self.assertEqual(w.warnings[0].category, SyntaxWarning) def test_fstring_backslash_prefix_raw(self): self.assertEqual(f'\\', '\\') self.assertEqual(f'\\\\', '\\\\') self.assertEqual(fr'\\', r'\\') self.assertEqual(fr'\\\\', r'\\\\') self.assertEqual(rf'\\', r'\\') self.assertEqual(rf'\\\\', r'\\\\') self.assertEqual(Rf'\\', R'\\') self.assertEqual(Rf'\\\\', R'\\\\') self.assertEqual(fR'\\', R'\\') self.assertEqual(fR'\\\\', R'\\\\') self.assertEqual(FR'\\', R'\\') self.assertEqual(FR'\\\\', R'\\\\') def test_fstring_format_spec_greedy_matching(self): self.assertEqual(f"{1:}}}", "1}") self.assertEqual(f"{1:>3{5}}}}", " 1}") def test_yield(self): # Not terribly useful, but make sure the yield turns # a function into a generator def fn(y): f'y:{yield y*2}' f'{yield}' g = fn(4) self.assertEqual(next(g), 8) self.assertEqual(next(g), None) def test_yield_send(self): def fn(x): yield f'x:{yield (lambda i: x * i)}' g = fn(10) the_lambda = next(g) self.assertEqual(the_lambda(4), 40) self.assertEqual(g.send('string'), 'x:string') def test_expressions_with_triple_quoted_strings(self): self.assertEqual(f"{'''x'''}", 'x') self.assertEqual(f"{'''eric's'''}", "eric's") # Test concatenation within an expression self.assertEqual(f'{"x" """eric"s""" "y"}', 'xeric"sy') self.assertEqual(f'{"x" """eric"s"""}', 'xeric"s') self.assertEqual(f'{"""eric"s""" "y"}', 'eric"sy') self.assertEqual(f'{"""x""" """eric"s""" "y"}', 'xeric"sy') self.assertEqual(f'{"""x""" """eric"s""" """y"""}', 'xeric"sy') self.assertEqual(f'{r"""x""" """eric"s""" """y"""}', 'xeric"sy') def test_multiple_vars(self): x = 98 y = 'abc' self.assertEqual(f'{x}{y}', '98abc') self.assertEqual(f'X{x}{y}', 'X98abc') self.assertEqual(f'{x}X{y}', '98Xabc') self.assertEqual(f'{x}{y}X', '98abcX') self.assertEqual(f'X{x}Y{y}', 'X98Yabc') self.assertEqual(f'X{x}{y}Y', 'X98abcY') self.assertEqual(f'{x}X{y}Y', '98XabcY') self.assertEqual(f'X{x}Y{y}Z', 'X98YabcZ') def test_closure(self): def outer(x): def inner(): return f'x:{x}' return inner self.assertEqual(outer('987')(), 'x:987') self.assertEqual(outer(7)(), 'x:7') def test_arguments(self): y = 2 def f(x, width): return f'x={x*y:{width}}' self.assertEqual(f('foo', 10), 'x=foofoo ') x = 'bar' self.assertEqual(f(10, 10), 'x= 20') def test_locals(self): value = 123 self.assertEqual(f'v:{value}', 'v:123') def test_missing_variable(self): with self.assertRaises(NameError): f'v:{value}' def test_missing_format_spec(self): class O: def __format__(self, spec): if not spec: return '*' return spec self.assertEqual(f'{O():x}', 'x') self.assertEqual(f'{O()}', '*') self.assertEqual(f'{O():}', '*') self.assertEqual(f'{3:}', '3') self.assertEqual(f'{3!s:}', '3') def test_global(self): self.assertEqual(f'g:{a_global}', 'g:global variable') self.assertEqual(f'g:{a_global!r}', "g:'global variable'") a_local = 'local variable' self.assertEqual(f'g:{a_global} l:{a_local}', 'g:global variable l:local variable') self.assertEqual(f'g:{a_global!r}', "g:'global variable'") self.assertEqual(f'g:{a_global} l:{a_local!r}', "g:global variable l:'local variable'") self.assertIn("module 'unittest' from", f'{unittest}') def test_shadowed_global(self): a_global = 'really a local' self.assertEqual(f'g:{a_global}', 'g:really a local') self.assertEqual(f'g:{a_global!r}', "g:'really a local'") a_local = 'local variable' self.assertEqual(f'g:{a_global} l:{a_local}', 'g:really a local l:local variable') self.assertEqual(f'g:{a_global!r}', "g:'really a local'") self.assertEqual(f'g:{a_global} l:{a_local!r}', "g:really a local l:'local variable'") def test_call(self): def foo(x): return 'x=' + str(x) self.assertEqual(f'{foo(10)}', 'x=10') def test_nested_fstrings(self): y = 5 self.assertEqual(f'{f"{0}"*3}', '000') self.assertEqual(f'{f"{y}"*3}', '555') def test_invalid_string_prefixes(self): single_quote_cases = ["fu''", "uf''", "Fu''", "fU''", "Uf''", "uF''", "ufr''", "urf''", "fur''", "fru''", "rfu''", "ruf''", "FUR''", "Fur''", "fb''", "fB''", "Fb''", "FB''", "bf''", "bF''", "Bf''", "BF''",] double_quote_cases = [case.replace("'", '"') for case in single_quote_cases] self.assertAllRaise(SyntaxError, 'invalid syntax', single_quote_cases + double_quote_cases) def test_leading_trailing_spaces(self): self.assertEqual(f'{ 3}', '3') self.assertEqual(f'{ 3}', '3') self.assertEqual(f'{3 }', '3') self.assertEqual(f'{3 }', '3') self.assertEqual(f'expr={ {x: y for x, y in [(1, 2), ]}}', 'expr={1: 2}') self.assertEqual(f'expr={ {x: y for x, y in [(1, 2), ]} }', 'expr={1: 2}') def test_not_equal(self): # There's a special test for this because there's a special # case in the f-string parser to look for != as not ending an # expression. Normally it would, while looking for !s or !r. self.assertEqual(f'{3!=4}', 'True') self.assertEqual(f'{3!=4:}', 'True') self.assertEqual(f'{3!=4!s}', 'True') self.assertEqual(f'{3!=4!s:.3}', 'Tru') def test_equal_equal(self): # Because an expression ending in = has special meaning, # there's a special test for ==. Make sure it works. self.assertEqual(f'{0==1}', 'False') def test_conversions(self): self.assertEqual(f'{3.14:10.10}', ' 3.14') self.assertEqual(f'{3.14!s:10.10}', '3.14 ') self.assertEqual(f'{3.14!r:10.10}', '3.14 ') self.assertEqual(f'{3.14!a:10.10}', '3.14 ') self.assertEqual(f'{"a"}', 'a') self.assertEqual(f'{"a"!r}', "'a'") self.assertEqual(f'{"a"!a}', "'a'") # Conversions can have trailing whitespace after them since it # does not provide any significance self.assertEqual(f"{3!s }", "3") self.assertEqual(f'{3.14!s :10.10}', '3.14 ') # Not a conversion. self.assertEqual(f'{"a!r"}', "a!r") # Not a conversion, but show that ! is allowed in a format spec. self.assertEqual(f'{3.14:!<10.10}', '3.14!!!!!!') self.assertAllRaise(SyntaxError, "f-string: expecting '}'", ["f'{3!'", "f'{3!s'", "f'{3!g'", ]) self.assertAllRaise(SyntaxError, 'f-string: missing conversion character', ["f'{3!}'", "f'{3!:'", "f'{3!:}'", ]) for conv_identifier in 'g', 'A', 'G', 'ä', 'ɐ': self.assertAllRaise(SyntaxError, "f-string: invalid conversion character %r: " "expected 's', 'r', or 'a'" % conv_identifier, ["f'{3!" + conv_identifier + "}'"]) for conv_non_identifier in '3', '!': self.assertAllRaise(SyntaxError, "f-string: invalid conversion character", ["f'{3!" + conv_non_identifier + "}'"]) for conv in ' s', ' s ': self.assertAllRaise(SyntaxError, "f-string: conversion type must come right after the" " exclamanation mark", ["f'{3!" + conv + "}'"]) self.assertAllRaise(SyntaxError, "f-string: invalid conversion character 'ss': " "expected 's', 'r', or 'a'", ["f'{3!ss}'", "f'{3!ss:}'", "f'{3!ss:s}'", ]) def test_assignment(self): self.assertAllRaise(SyntaxError, r'invalid syntax', ["f'' = 3", "f'{0}' = x", "f'{x}' = x", ]) def test_del(self): self.assertAllRaise(SyntaxError, 'invalid syntax', ["del f''", "del '' f''", ]) def test_mismatched_braces(self): self.assertAllRaise(SyntaxError, "f-string: single '}' is not allowed", ["f'{{}'", "f'{{}}}'", "f'}'", "f'x}'", "f'x}x'", r"f'\u007b}'", # Can't have { or } in a format spec. "f'{3:}>10}'", "f'{3:}}>10}'", ]) self.assertAllRaise(SyntaxError, "f-string: expecting '}'", ["f'{3'", "f'{3!'", "f'{3:'", "f'{3!s'", "f'{3!s:'", "f'{3!s:3'", "f'x{'", "f'x{x'", "f'{x'", "f'{3:s'", "f'{{{'", "f'{{}}{'", "f'{'", "f'{i='", # See gh-93418. ]) self.assertAllRaise(SyntaxError, "f-string: expecting a valid expression after '{'", ["f'{3:{{>10}'", ]) # But these are just normal strings. self.assertEqual(f'{"{"}', '{') self.assertEqual(f'{"}"}', '}') self.assertEqual(f'{3:{"}"}>10}', '}}}}}}}}}3') self.assertEqual(f'{2:{"{"}>10}', '{{{{{{{{{2') def test_if_conditional(self): # There's special logic in compile.c to test if the # conditional for an if (and while) are constants. Exercise # that code. def test_fstring(x, expected): flag = 0 if f'{x}': flag = 1 else: flag = 2 self.assertEqual(flag, expected) def test_concat_empty(x, expected): flag = 0 if '' f'{x}': flag = 1 else: flag = 2 self.assertEqual(flag, expected) def test_concat_non_empty(x, expected): flag = 0 if ' ' f'{x}': flag = 1 else: flag = 2 self.assertEqual(flag, expected) test_fstring('', 2) test_fstring(' ', 1) test_concat_empty('', 2) test_concat_empty(' ', 1) test_concat_non_empty('', 1) test_concat_non_empty(' ', 1) def test_empty_format_specifier(self): x = 'test' self.assertEqual(f'{x}', 'test') self.assertEqual(f'{x:}', 'test') self.assertEqual(f'{x!s:}', 'test') self.assertEqual(f'{x!r:}', "'test'") def test_str_format_differences(self): d = {'a': 'string', 0: 'integer', } a = 0 self.assertEqual(f'{d[0]}', 'integer') self.assertEqual(f'{d["a"]}', 'string') self.assertEqual(f'{d[a]}', 'integer') self.assertEqual('{d[a]}'.format(d=d), 'string') self.assertEqual('{d[0]}'.format(d=d), 'integer') def test_errors(self): # see issue 26287 self.assertAllRaise(TypeError, 'unsupported', [r"f'{(lambda: 0):x}'", r"f'{(0,):x}'", ]) self.assertAllRaise(ValueError, 'Unknown format code', [r"f'{1000:j}'", r"f'{1000:j}'", ]) def test_filename_in_syntaxerror(self): # see issue 38964 with temp_cwd() as cwd: file_path = os.path.join(cwd, 't.py') with open(file_path, 'w', encoding="utf-8") as f: f.write('f"{a b}"') # This generates a SyntaxError _, _, stderr = assert_python_failure(file_path, PYTHONIOENCODING='ascii') self.assertIn(file_path.encode('ascii', 'backslashreplace'), stderr) def test_loop(self): for i in range(1000): self.assertEqual(f'i:{i}', 'i:' + str(i)) def test_dict(self): d = {'"': 'dquote', "'": 'squote', 'foo': 'bar', } self.assertEqual(f'''{d["'"]}''', 'squote') self.assertEqual(f"""{d['"']}""", 'dquote') self.assertEqual(f'{d["foo"]}', 'bar') self.assertEqual(f"{d['foo']}", 'bar') def test_backslash_char(self): # Check eval of a backslash followed by a control char. # See bpo-30682: this used to raise an assert in pydebug mode. self.assertEqual(eval('f"\\\n"'), '') self.assertEqual(eval('f"\\\r"'), '') def test_debug_conversion(self): x = 'A string' self.assertEqual(f'{x=}', 'x=' + repr(x)) self.assertEqual(f'{x =}', 'x =' + repr(x)) self.assertEqual(f'{x=!s}', 'x=' + str(x)) self.assertEqual(f'{x=!r}', 'x=' + repr(x)) self.assertEqual(f'{x=!a}', 'x=' + ascii(x)) x = 2.71828 self.assertEqual(f'{x=:.2f}', 'x=' + format(x, '.2f')) self.assertEqual(f'{x=:}', 'x=' + format(x, '')) self.assertEqual(f'{x=!r:^20}', 'x=' + format(repr(x), '^20')) self.assertEqual(f'{x=!s:^20}', 'x=' + format(str(x), '^20')) self.assertEqual(f'{x=!a:^20}', 'x=' + format(ascii(x), '^20')) x = 9 self.assertEqual(f'{3*x+15=}', '3*x+15=42') # There is code in ast.c that deals with non-ascii expression values. So, # use a unicode identifier to trigger that. tenπ = 31.4 self.assertEqual(f'{tenπ=:.2f}', 'tenπ=31.40') # Also test with Unicode in non-identifiers. self.assertEqual(f'{"Σ"=}', '"Σ"=\'Σ\'') # Make sure nested fstrings still work. self.assertEqual(f'{f"{3.1415=:.1f}":*^20}', '*****3.1415=3.1*****') # Make sure text before and after an expression with = works # correctly. pi = 'π' self.assertEqual(f'alpha α {pi=} ω omega', "alpha α pi='π' ω omega") # Check multi-line expressions. self.assertEqual(f'''{ 3 =}''', '\n3\n=3') # Since = is handled specially, make sure all existing uses of # it still work. self.assertEqual(f'{0==1}', 'False') self.assertEqual(f'{0!=1}', 'True') self.assertEqual(f'{0<=1}', 'True') self.assertEqual(f'{0>=1}', 'False') self.assertEqual(f'{(x:="5")}', '5') self.assertEqual(x, '5') self.assertEqual(f'{(x:=5)}', '5') self.assertEqual(x, 5) self.assertEqual(f'{"="}', '=') x = 20 # This isn't an assignment expression, it's 'x', with a format # spec of '=10'. See test_walrus: you need to use parens. self.assertEqual(f'{x:=10}', ' 20') # Test named function parameters, to make sure '=' parsing works # there. def f(a): nonlocal x oldx = x x = a return oldx x = 0 self.assertEqual(f'{f(a="3=")}', '0') self.assertEqual(x, '3=') self.assertEqual(f'{f(a=4)}', '3=') self.assertEqual(x, 4) # Make sure __format__ is being called. class C: def __format__(self, s): return f'FORMAT-{s}' def __repr__(self): return 'REPR' self.assertEqual(f'{C()=}', 'C()=REPR') self.assertEqual(f'{C()=!r}', 'C()=REPR') self.assertEqual(f'{C()=:}', 'C()=FORMAT-') self.assertEqual(f'{C()=: }', 'C()=FORMAT- ') self.assertEqual(f'{C()=:x}', 'C()=FORMAT-x') self.assertEqual(f'{C()=!r:*^20}', 'C()=********REPR********') self.assertRaises(SyntaxError, eval, "f'{C=]'") # Make sure leading and following text works. x = 'foo' self.assertEqual(f'X{x=}Y', 'Xx='+repr(x)+'Y') # Make sure whitespace around the = works. self.assertEqual(f'X{x =}Y', 'Xx ='+repr(x)+'Y') self.assertEqual(f'X{x= }Y', 'Xx= '+repr(x)+'Y') self.assertEqual(f'X{x = }Y', 'Xx = '+repr(x)+'Y') self.assertEqual(f"sadsd {1 + 1 = :{1 + 1:1d}f}", "sadsd 1 + 1 = 2.000000") # These next lines contains tabs. Backslash escapes don't # work in f-strings. # patchcheck doesn't like these tabs. So the only way to test # this will be to dynamically created and exec the f-strings. But # that's such a hassle I'll save it for another day. For now, convert # the tabs to spaces just to shut up patchcheck. #self.assertEqual(f'X{x =}Y', 'Xx\t='+repr(x)+'Y') #self.assertEqual(f'X{x = }Y', 'Xx\t=\t'+repr(x)+'Y') def test_walrus(self): x = 20 # This isn't an assignment expression, it's 'x', with a format # spec of '=10'. self.assertEqual(f'{x:=10}', ' 20') # This is an assignment expression, which requires parens. self.assertEqual(f'{(x:=10)}', '10') self.assertEqual(x, 10) def test_invalid_syntax_error_message(self): with self.assertRaisesRegex(SyntaxError, "f-string: expecting '=', or '!', or ':', or '}'"): compile("f'{a $ b}'", "?", "exec") def test_with_two_commas_in_format_specifier(self): error_msg = re.escape("Cannot specify ',' with ','.") with self.assertRaisesRegex(ValueError, error_msg): f'{1:,,}' def test_with_two_underscore_in_format_specifier(self): error_msg = re.escape("Cannot specify '_' with '_'.") with self.assertRaisesRegex(ValueError, error_msg): f'{1:__}' def test_with_a_commas_and_an_underscore_in_format_specifier(self): error_msg = re.escape("Cannot specify both ',' and '_'.") with self.assertRaisesRegex(ValueError, error_msg): f'{1:,_}' def test_with_an_underscore_and_a_comma_in_format_specifier(self): error_msg = re.escape("Cannot specify both ',' and '_'.") with self.assertRaisesRegex(ValueError, error_msg): f'{1:_,}' def test_syntax_error_for_starred_expressions(self): with self.assertRaisesRegex(SyntaxError, "can't use starred expression here"): compile("f'{*a}'", "?", "exec") with self.assertRaisesRegex(SyntaxError, "f-string: expecting a valid expression after '{'"): compile("f'{**a}'", "?", "exec") def test_not_closing_quotes(self): self.assertAllRaise(SyntaxError, "unterminated f-string literal", ['f"', "f'"]) self.assertAllRaise(SyntaxError, "unterminated triple-quoted f-string literal", ['f"""', "f'''"]) # Ensure that the errors are reported at the correct line number. data = '''\ x = 1 + 1 y = 2 + 2 z = f""" sdfjnsdfjsdf sdfsdfs{1+ 2} dfigdf {3+ 4}sdufsd"" ''' try: compile(data, "?", "exec") except SyntaxError as e: self.assertEqual(e.text, 'z = f"""') self.assertEqual(e.lineno, 3) def test_syntax_error_after_debug(self): self.assertAllRaise(SyntaxError, "f-string: expecting a valid expression after '{'", [ "f'{1=}{;'", "f'{1=}{+;'", "f'{1=}{2}{;'", "f'{1=}{3}{;'", ]) self.assertAllRaise(SyntaxError, "f-string: expecting '=', or '!', or ':', or '}'", [ "f'{1=}{1;'", "f'{1=}{1;}'", ]) def test_debug_in_file(self): with temp_cwd(): script = 'script.py' with open('script.py', 'w') as f: f.write(f"""\ print(f'''{{ 3 =}}''')""") _, stdout, _ = assert_python_ok(script) self.assertEqual(stdout.decode('utf-8').strip().replace('\r\n', '\n').replace('\r', '\n'), "3\n=3") def test_syntax_warning_infinite_recursion_in_file(self): with temp_cwd(): script = 'script.py' with open(script, 'w') as f: f.write(r"print(f'\{1}')") _, stdout, stderr = assert_python_ok(script) self.assertIn(rb'\1', stdout) self.assertEqual(len(stderr.strip().splitlines()), 2) if __name__ == '__main__': unittest.main()