[formatter] Add "preserve" quote-style to mimic Black's skip-string-n…

…ormalization

Fixes #7525

crates/ruff_python_formatter/src/expression/string.rs

@@ -443,7 +443,9 @@ impl StringPart {
         let quotes = match quoting {
             Quoting::Preserve => self.quotes,
             Quoting::CanChange => {
-                if self.prefix.is_raw_string() {
+                if preferred_style == QuoteStyle::Preserve {
+                    self.quotes
+                } else if self.prefix.is_raw_string() {
                     choose_quotes_raw(raw_content, self.quotes, preferred_style)
                 } else {
                     choose_quotes(raw_content, self.quotes, preferred_style)
@@ -722,7 +724,7 @@ fn choose_quotes(input: &str, quotes: StringQuotes, preferred_style: QuoteStyle)
                     QuoteStyle::Single
                 }
             }
-            QuoteStyle::Double => {
+            QuoteStyle::Double | QuoteStyle::Preserve => {
                 if double_quotes > single_quotes {
                     QuoteStyle::Single
                 } else {
@@ -774,8 +776,8 @@ impl Format<PyFormatContext<'_>> for StringQuotes {
         let quotes = match (self.style, self.triple) {
             (QuoteStyle::Single, false) => "'",
             (QuoteStyle::Single, true) => "'''",
-            (QuoteStyle::Double, false) => "\"",
-            (QuoteStyle::Double, true) => "\"\"\"",
+            (QuoteStyle::Double | QuoteStyle::Preserve, false) => "\"",
+            (QuoteStyle::Double | QuoteStyle::Preserve, true) => "\"\"\"",
         };
 
         token(quotes).fmt(f)

crates/ruff_python_formatter/src/options.rs

@@ -190,13 +190,15 @@ pub enum QuoteStyle {
     Single,
     #[default]
     Double,
+    Preserve,
 }
 
 impl QuoteStyle {
     pub const fn as_char(self) -> char {
         match self {
             QuoteStyle::Single => '\'',
             QuoteStyle::Double => '"',
+            QuoteStyle::Preserve => '"', // not used
         }
     }
 
@@ -205,6 +207,7 @@ impl QuoteStyle {
         match self {
             QuoteStyle::Single => QuoteStyle::Double,
             QuoteStyle::Double => QuoteStyle::Single,
+            QuoteStyle::Preserve => QuoteStyle::Preserve,
         }
     }
 }
@@ -228,6 +231,7 @@ impl FromStr for QuoteStyle {
         match s {
             "\"" | "double" | "Double" => Ok(Self::Double),
             "'" | "single" | "Single" => Ok(Self::Single),
+            "preserve" | "Preserve" => Ok(Self::Preserve),
             // TODO: replace this error with a diagnostic
             _ => Err("Value not supported for QuoteStyle"),
         }

pyproject.toml

@@ -50,16 +50,14 @@ python-source = "python"
 strip = true
 exclude = [
   "crates/ruff_linter/resources/test/fixtures/**/*",
-  "crates/ruff_linter/src/rules/*/snapshots/**/*"
-]
-include = [
-  "rust-toolchain.toml"
+  "crates/ruff_linter/src/rules/*/snapshots/**/*",
 ]
+include = ["rust-toolchain.toml"]
 
 [tool.ruff]
 extend-exclude = [
   "crates/ruff_linter/resources/",
-  "crates/ruff_python_formatter/resources/"
+  "crates/ruff_python_formatter/resources/",
 ]
 
 [tool.black]
@@ -71,8 +69,8 @@ force-exclude = '''
 '''
 
 [tool.rooster]
-major_labels = []  # Ruff never uses the major version number
-minor_labels = ["breaking"]   # Bump the minor version on breaking changes
+major_labels = []           # Ruff never uses the major version number
+minor_labels = ["breaking"] # Bump the minor version on breaking changes
 
 changelog_ignore_labels = ["internal"]
 
@@ -91,7 +89,7 @@ changelog_sections.__unknown__ = "Other changes"
 changelog_contributors = false
 
 version_files = [
-  "README.md", 
+  "README.md",
   "docs/integrations.md",
   "crates/flake8_to_ruff/Cargo.toml",
   "crates/ruff_cli/Cargo.toml",