Use the preferred quotes for literals in triple quoted f-strings

crates/ruff_python_formatter/src/string/normalize.rs

@@ -53,14 +53,6 @@ impl<'a, 'src> StringNormalizer<'a, 'src> {
                     return QuoteStyle::Preserve;
                 }
 
-                if let FStringState::InsideExpressionElement(parent_context) =
-                    self.context.f_string_state()
-                {
-                    return QuoteStyle::from(
-                        parent_context.f_string().flags().quote_style().opposite(),
-                    );
-                }
-
                 // Per PEP 8, always prefer double quotes for triple-quoted strings.
                 // Except when using quote-style-preserve.
                 if string.flags().is_triple_quoted() {
@@ -115,6 +107,20 @@ impl<'a, 'src> StringNormalizer<'a, 'src> {
                         QuoteStyle::Double
                     }
                 } else {
+                    // For f-strings prefer alternating the quotes unless it's a triple quoted string,
+                    // then prefer using the preferred quotes.
+                    if let FStringState::InsideExpressionElement(parent_context) =
+                        self.context.f_string_state()
+                    {
+                        let parent_flags = parent_context.f_string().flags();
+
+                        if !parent_flags.is_triple_quoted() {
+                            return QuoteStyle::from(
+                                parent_context.f_string().flags().quote_style().opposite(),
+                            );
+                        }
+                    }
+
                     preferred_quote_style
                 }
             }
@@ -275,7 +281,10 @@ impl QuoteMetadata {
             StringLikePart::FString(fstring) => {
                 // TODO: Should we limit this behavior to Post 312?
                 if is_f_string_formatting_enabled(context) {
-                    let mut literals = fstring.elements.iter().filter_map(FStringElement::as_literal);
+                    let mut literals = fstring
+                        .elements
+                        .iter()
+                        .filter_map(FStringElement::as_literal);
 
                     let Some(first) = literals.next() else {
                         return QuoteMetadata::from_str("", part.flags(), preferred_quote);

crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__preview_long_strings.py.snap

@@ -902,7 +902,7 @@ log.info(f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share
  )
 
  dict_with_lambda_values = {
-@@ -524,69 +383,62 @@
+@@ -524,65 +383,58 @@
 
  # Complex string concatenations with a method call in the middle.
  code = (
@@ -982,15 +982,17 @@ log.info(f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share
 
  log.info(
 -    f"""Skipping: {"a" == 'b'} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
-+    f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
++    f"""Skipping: {"a" == "b"} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
  )
 
  log.info(
--    f"""Skipping: {'a' == "b"=} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
-+    f"""Skipping: {'a' == "b"=} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
+@@ -590,5 +442,5 @@
  )
 
  log.info(
+-    f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
++    f"""Skipping: {"a" == "b"} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
+ )
 ```
 
 ## Ruff Output
@@ -1432,15 +1434,15 @@ log.info(
 )
 
 log.info(
-    f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
+    f"""Skipping: {"a" == "b"} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
 )
 
 log.info(
-    f"""Skipping: {'a' == "b"=} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
+    f"""Skipping: {'a' == "b"=} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
 )
 
 log.info(
-    f"""Skipping: {'a' == 'b'} {desc['ms_name']} {money=} {dte=} {pos_share=} {desc['status']} {desc['exposure_max']}"""
+    f"""Skipping: {"a" == "b"} {desc["ms_name"]} {money=} {dte=} {pos_share=} {desc["status"]} {desc["exposure_max"]}"""
 )
 ```
 

crates/ruff_python_formatter/tests/snapshots/format@expression__fstring.py.snap

@@ -399,9 +399,9 @@ result_f = (
 )
 
 # https://github.com/astral-sh/ruff/issues/6841
-x = f"""a{''}b"""
+x = f"""a{""}b"""
 y = f'''c{1}d"""e'''
-z = f"""a{''}b""" f'''c{1}d"""e'''
+z = f"""a{""}b""" f'''c{1}d"""e'''
 
 # F-String formatting test cases (Preview)
 
@@ -511,10 +511,10 @@ f"foo {'"bar"'}"
 
 # Triple-quoted strings
 # It's ok to use the same quote char for the inner string if it's single-quoted.
-f"""test {'inner'}"""
-f"""test {'inner'}"""
+f"""test {"inner"}"""
+f"""test {"inner"}"""
 # But if the inner string is also triple-quoted then we should preserve the existing quotes.
-f"""test {'''inner'''}"""
+f"""test {"""inner"""}"""
 
 # Magic trailing comma
 #
@@ -616,10 +616,10 @@ x = f"""
 # Here, the debug expression is in a nested f-string so we should start preserving
 # whitespaces from that point onwards. This means we should format the outer f-string.
 x = f"""{
-    'foo '  # comment 24
-    + f'{   x =
+    "foo "  # comment 24
+    + f"{   x =
 
-       }'  # comment 25
+       }"  # comment 25
 }
         """
 
@@ -641,19 +641,19 @@ if indent0:
         if indent2:
             foo = f"""hello world
 hello {
-                f'aaaaaaa {
+                f"aaaaaaa {
                     [
-                        "aaaaaaaaaaaaaaaaaaaaa",
-                        "bbbbbbbbbbbbbbbbbbbbb",
-                        "ccccccccccccccccccccc",
-                        "ddddddddddddddddddddd",
+                        'aaaaaaaaaaaaaaaaaaaaa',
+                        'bbbbbbbbbbbbbbbbbbbbb',
+                        'ccccccccccccccccccccc',
+                        'ddddddddddddddddddddd',
                     ]
-                } bbbbbbbb'
+                } bbbbbbbb"
                 + [
-                    'aaaaaaaaaaaaaaaaaaaaa',
-                    'bbbbbbbbbbbbbbbbbbbbb',
-                    'ccccccccccccccccccccc',
-                    'ddddddddddddddddddddd',
+                    "aaaaaaaaaaaaaaaaaaaaa",
+                    "bbbbbbbbbbbbbbbbbbbbb",
+                    "ccccccccccccccccccccc",
+                    "ddddddddddddddddddddd",
                 ]
             } --------
 """
@@ -1022,18 +1022,6 @@ _ = (
      "    f()\n"
      # XXX: The following line changes depending on whether the tests
      # are run through the interactive interpreter or with -m
-@@ -57,9 +57,9 @@
- )
- 
- # https://github.com/astral-sh/ruff/issues/6841
--x = f"""a{""}b"""
-+x = f"""a{''}b"""
- y = f'''c{1}d"""e'''
--z = f"""a{""}b""" f'''c{1}d"""e'''
-+z = f"""a{''}b""" f'''c{1}d"""e'''
- 
- # F-String formatting test cases (Preview)
- 
 @@ -67,64 +67,72 @@
  x = f"{a}"
  x = f"{
@@ -1144,7 +1132,7 @@ _ = (
  }"
  
  # Quotes
-@@ -147,18 +159,18 @@
+@@ -147,20 +159,20 @@
  f'foo "bar" {x}'
  f'foo "bar" {x}'
  f"foo 'bar' {x}"
@@ -1161,12 +1149,15 @@ _ = (
  
  # Triple-quoted strings
  # It's ok to use the same quote char for the inner string if it's single-quoted.
- f"""test {'inner'}"""
--f"""test {"inner"}"""
-+f"""test {'inner'}"""
+-f"""test {'inner'}"""
+ f"""test {"inner"}"""
++f"""test {"inner"}"""
  # But if the inner string is also triple-quoted then we should preserve the existing quotes.
- f"""test {'''inner'''}"""
+-f"""test {'''inner'''}"""
++f"""test {"""inner"""}"""
  
+ # Magic trailing comma
+ #
 @@ -171,63 +183,66 @@
  f"aaaaaaa {['aaaaaaaaaaaaaaa', 'bbbbbbbbbbbbb', 'ccccccccccccccccc', 'ddddddddddddddd', 'eeeeeeeeeeeeee']} aaaaaaa"
  
@@ -1301,12 +1292,12 @@ _ = (
 -x = f"""{"foo " +    # comment 24
 -    f"{   x =
 +x = f"""{
-+    'foo '  # comment 24
-+    + f'{   x =
++    "foo "  # comment 24
++    + f"{   x =
  
 -       }"    # comment 25
 - }
-+       }'  # comment 25
++       }"  # comment 25
 +}
          """
  
@@ -1341,19 +1332,19 @@ _ = (
 -              'ddddddddddddddddddddd'
 -          ]
 -      } --------
-+                f'aaaaaaa {
++                f"aaaaaaa {
 +                    [
-+                        "aaaaaaaaaaaaaaaaaaaaa",
-+                        "bbbbbbbbbbbbbbbbbbbbb",
-+                        "ccccccccccccccccccccc",
-+                        "ddddddddddddddddddddd",
++                        'aaaaaaaaaaaaaaaaaaaaa',
++                        'bbbbbbbbbbbbbbbbbbbbb',
++                        'ccccccccccccccccccccc',
++                        'ddddddddddddddddddddd',
 +                    ]
-+                } bbbbbbbb'
++                } bbbbbbbb"
 +                + [
-+                    'aaaaaaaaaaaaaaaaaaaaa',
-+                    'bbbbbbbbbbbbbbbbbbbbb',
-+                    'ccccccccccccccccccccc',
-+                    'ddddddddddddddddddddd',
++                    "aaaaaaaaaaaaaaaaaaaaa",
++                    "bbbbbbbbbbbbbbbbbbbbb",
++                    "ccccccccccccccccccccc",
++                    "ddddddddddddddddddddd",
 +                ]
 +            } --------
  """