mirror of https://github.com/astral-sh/ruff
c3f61a012e
## Summary Addresses #11974 to add a `RUF` rule to replace `print` expressions in `assert` statements with the inner message. An autofix is available, but is considered unsafe as it changes behaviour of the execution, notably: - removal of the printout in `stdout`, and - `AssertionError` instance containing a different message. While the detection of the condition is a straightforward matter, deciding how to resolve the print arguments into a string literal can be a relatively subjective matter. The implementation of this PR chooses to be as tolerant as possible, and will attempt to reformat any number of `print` arguments containing single or concatenated strings or variables into either a string literal, or a f-string if any variables or placeholders are detected. ## Test Plan `cargo test`. ## Examples For ease of discussion, this is the diff for the tests: ```diff # Standard Case # Expects: # - single StringLiteral -assert True, print("This print is not intentional.") +assert True, "This print is not intentional." # Concatenated string literals # Expects: # - single StringLiteral -assert True, print("This print" " is not intentional.") +assert True, "This print is not intentional." # Positional arguments, string literals # Expects: # - single StringLiteral concatenated with " " -assert True, print("This print", "is not intentional") +assert True, "This print is not intentional" # Concatenated string literals combined with Positional arguments # Expects: # - single stringliteral concatenated with " " only between `print` and `is` -assert True, print("This " "print", "is not intentional.") +assert True, "This print is not intentional." # Positional arguments, string literals with a variable # Expects: # - single FString concatenated with " " -assert True, print("This", print.__name__, "is not intentional.") +assert True, f"This {print.__name__} is not intentional." # Mixed brackets string literals # Expects: # - single StringLiteral concatenated with " " -assert True, print("This print", 'is not intentional', """and should be removed""") +assert True, "This print is not intentional and should be removed" # Mixed brackets with other brackets inside # Expects: # - single StringLiteral concatenated with " " and escaped brackets -assert True, print("This print", 'is not "intentional"', """and "should" be 'removed'""") +assert True, "This print is not \"intentional\" and \"should\" be 'removed'" # Positional arguments, string literals with a separator # Expects: # - single StringLiteral concatenated with "|" -assert True, print("This print", "is not intentional", sep="|") +assert True, "This print|is not intentional" # Positional arguments, string literals with None as separator # Expects: # - single StringLiteral concatenated with " " -assert True, print("This print", "is not intentional", sep=None) +assert True, "This print is not intentional" # Positional arguments, string literals with variable as separator, needs f-string # Expects: # - single FString concatenated with "{U00A0}" -assert True, print("This print", "is not intentional", sep=U00A0) +assert True, f"This print{U00A0}is not intentional" # Unnecessary f-string # Expects: # - single StringLiteral -assert True, print(f"This f-string is just a literal.") +assert True, "This f-string is just a literal." # Positional arguments, string literals and f-strings # Expects: # - single FString concatenated with " " -assert True, print("This print", f"is not {'intentional':s}") +assert True, f"This print is not {'intentional':s}" # Positional arguments, string literals and f-strings with a separator # Expects: # - single FString concatenated with "|" -assert True, print("This print", f"is not {'intentional':s}", sep="|") +assert True, f"This print|is not {'intentional':s}" # A single f-string # Expects: # - single FString -assert True, print(f"This print is not {'intentional':s}") +assert True, f"This print is not {'intentional':s}" # A single f-string with a redundant separator # Expects: # - single FString -assert True, print(f"This print is not {'intentional':s}", sep="|") +assert True, f"This print is not {'intentional':s}" # Complex f-string with variable as separator # Expects: # - single FString concatenated with "{U00A0}", all placeholders preserved condition = "True is True" maintainer = "John Doe" -assert True, print("Unreachable due to", condition, f", ask {maintainer} for advice", sep=U00A0) +assert True, f"Unreachable due to{U00A0}{condition}{U00A0}, ask {maintainer} for advice" # Empty print # Expects: # - `msg` entirely removed from assertion -assert True, print() +assert True # Empty print with separator # Expects: # - `msg` entirely removed from assertion -assert True, print(sep=" ") +assert True # Custom print function that actually returns a string # Expects: @@ -100,4 +100,4 @@ # Use of `builtins.print` # Expects: # - single StringLiteral -assert True, builtins.print("This print should be removed.") +assert True, "This print should be removed." ``` ## Known Issues The current implementation resolves all arguments and separators of the `print` expression into a single string, be it `StringLiteralValue::single` or a `FStringValue::single`. This: - potentially joins together strings well beyond the ideal character limit for each line, and - does not preserve multi-line strings in their original format, in favour of a single line `"...\n...\n..."` format. These are purely formatting issues only occurring in unusual scenarios. Additionally, the autofix will tolerate `print` calls that were previously invalid: ```python assert True, print("this", "should not be allowed", sep=42) ``` This will be transformed into ```python assert True, f"this{42}should not be allowed" ``` which some could argue is an alteration of behaviour. --------- Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com> |
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| .. | ||
| red_knot | ||
| red_knot_module_resolver | ||
| red_knot_python_semantic | ||
| ruff | ||
| ruff_benchmark | ||
| ruff_cache | ||
| ruff_db | ||
| ruff_dev | ||
| ruff_diagnostics | ||
| ruff_formatter | ||
| ruff_index | ||
| ruff_linter | ||
| ruff_macros | ||
| ruff_notebook | ||
| ruff_python_ast | ||
| ruff_python_ast_integration_tests | ||
| ruff_python_codegen | ||
| ruff_python_formatter | ||
| ruff_python_index | ||
| ruff_python_literal | ||
| ruff_python_parser | ||
| ruff_python_resolver | ||
| ruff_python_semantic | ||
| ruff_python_stdlib | ||
| ruff_python_trivia | ||
| ruff_python_trivia_integration_tests | ||
| ruff_server | ||
| ruff_source_file | ||
| ruff_text_size | ||
| ruff_wasm | ||
| ruff_workspace | ||