[pycodestyle] Add fix for multiple-imports-on-one-line (E401)

crates/ruff_linter/resources/test/fixtures/pycodestyle/E40.py

@@ -1,5 +1,16 @@
 #: E401
 import os, sys
+import re as regex, string  # also with a comment!
+import re as regex, string; x = 1
+
+x = 1; import re as regex, string
+
+
+def blah():
+    import datetime as dt, copy 
+    def nested_and_tested():
+        import builtins, textwrap as tw
+
 #: Okay
 import os
 import sys

crates/ruff_linter/src/rules/pycodestyle/mod.rs

@@ -67,6 +67,7 @@ mod tests {
     }
 
     #[test_case(Rule::IsLiteral, Path::new("constant_literals.py"))]
+    #[test_case(Rule::MultipleImportsOnOneLine, Path::new("E40.py"))]
     #[test_case(Rule::ModuleImportNotAtTopOfFile, Path::new("E402_0.py"))]
     #[test_case(Rule::TypeComparison, Path::new("E721.py"))]
     fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {

crates/ruff_linter/src/rules/pycodestyle/rules/imports.rs

@@ -1,6 +1,7 @@
-use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, violation};
 use ruff_python_ast::{Alias, PySourceType, Stmt};
+use ruff_python_trivia::{indentation_at_offset, PythonWhitespace};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
@@ -27,10 +28,16 @@ use crate::checkers::ast::Checker;
 pub struct MultipleImportsOnOneLine;
 
 impl Violation for MultipleImportsOnOneLine {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         format!("Multiple imports on one line")
     }
+
+    fn fix_title(&self) -> Option<String> {
+        Some(format!("Split imports onto multiple lines"))
+    }
 }
 
 /// ## What it does
@@ -85,9 +92,40 @@ impl Violation for ModuleImportNotAtTopOfFile {
 /// E401
 pub(crate) fn multiple_imports_on_one_line(checker: &mut Checker, stmt: &Stmt, names: &[Alias]) {
     if names.len() > 1 {
-        checker
-            .diagnostics
-            .push(Diagnostic::new(MultipleImportsOnOneLine, stmt.range()));
+        let mut diagnostic = Diagnostic::new(MultipleImportsOnOneLine, stmt.range());
+
+        if checker.settings.preview.is_enabled() {
+            let indentation = indentation_at_offset(stmt.start(), checker.locator()).unwrap_or("");
+
+            let mut replacement = String::new();
+
+            for item in names {
+                let Alias {
+                    range: _,
+                    name,
+                    asname,
+                } = item;
+
+                if let Some(asname) = asname {
+                    replacement = format!("{replacement}{indentation}import {name} as {asname}\n");
+                } else {
+                    replacement = format!("{replacement}{indentation}import {name}\n");
+                }
+            }
+
+            // remove leading whitespace because we start at the import keyword
+            replacement = replacement.trim_whitespace_start().to_string();
+
+            // remove trailing newline
+            replacement = replacement.trim_end_matches('\n').to_string();
+
+            diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
+                replacement,
+                stmt.range(),
+            )));
+        }
+
+        checker.diagnostics.push(diagnostic);
     }
 }
 

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E401_E40.py.snap

@@ -6,8 +6,60 @@ E40.py:2:1: E401 Multiple imports on one line
 1 | #: E401
 2 | import os, sys
   | ^^^^^^^^^^^^^^ E401
-3 | #: Okay
-4 | import os
+3 | import re as regex, string  # also with a comment!
+4 | import re as regex, string; x = 1
   |
+  = help: Split imports onto multiple lines
+
+E40.py:3:1: E401 Multiple imports on one line
+  |
+1 | #: E401
+2 | import os, sys
+3 | import re as regex, string  # also with a comment!
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^ E401
+4 | import re as regex, string; x = 1
+  |
+  = help: Split imports onto multiple lines
+
+E40.py:4:1: E401 Multiple imports on one line
+  |
+2 | import os, sys
+3 | import re as regex, string  # also with a comment!
+4 | import re as regex, string; x = 1
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^ E401
+5 | 
+6 | x = 1; import re as regex, string
+  |
+  = help: Split imports onto multiple lines
+
+E40.py:6:8: E401 Multiple imports on one line
+  |
+4 | import re as regex, string; x = 1
+5 | 
+6 | x = 1; import re as regex, string
+  |        ^^^^^^^^^^^^^^^^^^^^^^^^^^ E401
+  |
+  = help: Split imports onto multiple lines
+
+E40.py:10:5: E401 Multiple imports on one line
+   |
+ 9 | def blah():
+10 |     import datetime as dt, copy 
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ E401
+11 |     def nested_and_tested():
+12 |         import builtins, textwrap as tw
+   |
+   = help: Split imports onto multiple lines
+
+E40.py:12:9: E401 Multiple imports on one line
+   |
+10 |     import datetime as dt, copy 
+11 |     def nested_and_tested():
+12 |         import builtins, textwrap as tw
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ E401
+13 | 
+14 | #: Okay
+   |
+   = help: Split imports onto multiple lines
 
 

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E402_E40.py.snap

@@ -1,31 +1,164 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
-E40.py:55:1: E402 Module level import not at top of file
+E40.py:6:8: E402 Module level import not at top of file
+  |
+4 | import re as regex, string; x = 1
+5 | 
+6 | x = 1; import re as regex, string
+  |        ^^^^^^^^^^^^^^^^^^^^^^^^^^ E402
+  |
+
+E40.py:15:1: E402 Module level import not at top of file
+   |
+14 | #: Okay
+15 | import os
+   | ^^^^^^^^^ E402
+16 | import sys
+   |
+
+E40.py:16:1: E402 Module level import not at top of file
+   |
+14 | #: Okay
+15 | import os
+16 | import sys
+   | ^^^^^^^^^^ E402
+17 | 
+18 | from subprocess import Popen, PIPE
+   |
+
+E40.py:18:1: E402 Module level import not at top of file
+   |
+16 | import sys
+17 | 
+18 | from subprocess import Popen, PIPE
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ E402
+19 | 
+20 | from myclass import MyClass
+   |
+
+E40.py:20:1: E402 Module level import not at top of file
+   |
+18 | from subprocess import Popen, PIPE
+19 | 
+20 | from myclass import MyClass
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ E402
+21 | from foo.bar.yourclass import YourClass
+   |
+
+E40.py:21:1: E402 Module level import not at top of file
+   |
+20 | from myclass import MyClass
+21 | from foo.bar.yourclass import YourClass
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ E402
+22 | 
+23 | import myclass
+   |
+
+E40.py:23:1: E402 Module level import not at top of file
+   |
+21 | from foo.bar.yourclass import YourClass
+22 | 
+23 | import myclass
+   | ^^^^^^^^^^^^^^ E402
+24 | import foo.bar.yourclass
+25 | #: Okay
+   |
+
+E40.py:24:1: E402 Module level import not at top of file
+   |
+23 | import myclass
+24 | import foo.bar.yourclass
+   | ^^^^^^^^^^^^^^^^^^^^^^^^ E402
+25 | #: Okay
+26 | __all__ = ['abc']
+   |
+
+E40.py:28:1: E402 Module level import not at top of file
+   |
+26 | __all__ = ['abc']
+27 | 
+28 | import foo
+   | ^^^^^^^^^^ E402
+29 | #: Okay
+30 | __version__ = "42"
+   |
+
+E40.py:32:1: E402 Module level import not at top of file
+   |
+30 | __version__ = "42"
+31 | 
+32 | import foo
+   | ^^^^^^^^^^ E402
+33 | #: Okay
+34 | __author__ = "Simon Gomizelj"
+   |
+
+E40.py:36:1: E402 Module level import not at top of file
+   |
+34 | __author__ = "Simon Gomizelj"
+35 | 
+36 | import foo
+   | ^^^^^^^^^^ E402
+37 | #: Okay
+38 | try:
+   |
+
+E40.py:47:1: E402 Module level import not at top of file
+   |
+45 |     print('made attempt to import foo')
+46 | 
+47 | import bar
+   | ^^^^^^^^^^ E402
+48 | #: Okay
+49 | with warnings.catch_warnings():
+   |
+
+E40.py:53:1: E402 Module level import not at top of file
+   |
+51 |     import foo
+52 | 
+53 | import bar
+   | ^^^^^^^^^^ E402
+54 | #: Okay
+55 | if False:
+   |
+
+E40.py:62:1: E402 Module level import not at top of file
+   |
+60 |     import mwahaha
+61 | 
+62 | import bar
+   | ^^^^^^^^^^ E402
+63 | #: E402
+64 | VERSION = '1.2.3'
+   |
+
+E40.py:66:1: E402 Module level import not at top of file
    |
-53 | VERSION = '1.2.3'
-54 | 
-55 | import foo
+64 | VERSION = '1.2.3'
+65 | 
+66 | import foo
    | ^^^^^^^^^^ E402
-56 | #: E402
-57 | import foo
+67 | #: E402
+68 | import foo
    |
 
-E40.py:57:1: E402 Module level import not at top of file
+E40.py:68:1: E402 Module level import not at top of file
    |
-55 | import foo
-56 | #: E402
-57 | import foo
+66 | import foo
+67 | #: E402
+68 | import foo
    | ^^^^^^^^^^ E402
-58 | 
-59 | a = 1
+69 | 
+70 | a = 1
    |
 
-E40.py:61:1: E402 Module level import not at top of file
+E40.py:72:1: E402 Module level import not at top of file
    |
-59 | a = 1
-60 | 
-61 | import bar
+70 | a = 1
+71 | 
+72 | import bar
    | ^^^^^^^^^^ E402
    |