Consider quotes inside format-specs when choosing the quotes for an f-string (#14493)

crates/ruff_python_formatter/tests/snapshots/format@expression__fstring_py312.py.snap

@@ -22,6 +22,34 @@ f'{"""other " """ + "more"}'
 f'{b"""other " """}'
 f'{f"""other " """}'
 
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{'aa'}" }'
+f'{1=: "abcd {'aa'}}'
+f'{x:a{z:hy "user"}} \'\'\''
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f'{f'{z=:hy "user"}'} \'\'\''
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f'''{1=: "this" is fine}'''  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
 ```
 
 ## Outputs
@@ -57,6 +85,35 @@ f'{"""other " """}'
 f'{"""other " """ + "more"}'
 f'{b"""other " """}'
 f'{f"""other " """}'
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+f'{1: hy "user"}'
+f'{1:hy "user"}'
+f'{1: abcd "{1}" }'
+f'{1: abcd "{'aa'}" }'
+f'{1=: "abcd {'aa'}}'
+f'{x:a{z:hy "user"}} \'\'\''
+
+# Changing the outer quotes is fine because the format-spec is in a nested expression.
+f'{f'{z=:hy "user"}'} \'\'\''
+
+
+#  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
+# Don't change the quotes in the following cases:
+f'{x=:hy "user"} \'\'\''
+f'{x=:a{y:hy "user"}} \'\'\''
+f'{x=:a{y:{z:hy "user"}}} \'\'\''
+f'{x:a{y=:{z:hy "user"}}} \'\'\''
+
+# This is fine because the debug expression and format spec are in a nested expression
+
+f"""{1=: "this" is fine}"""
+f"""{1=: "this" is fine}"""  # Change quotes to double quotes because they're preferred
+f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
 ```
 
 
@@ -64,7 +121,7 @@ f'{f"""other " """}'
 ```diff
 --- Stable
 +++ Preview
-@@ -6,11 +6,11 @@
+@@ -6,32 +6,32 @@
  f"{'a'}"
  
  # 312+, it's okay to change the outer quotes even when there's a debug expression using the same quotes
@@ -82,4 +139,36 @@ f'{f"""other " """}'
 +f"{'''other " ''' + 'more'}"
 +f"{b'''other " '''}"
 +f"{f'''other " '''}"
+ 
+ 
+ # Regression tests for https://github.com/astral-sh/ruff/issues/13935
+ f'{1: hy "user"}'
+ f'{1:hy "user"}'
+ f'{1: abcd "{1}" }'
+-f'{1: abcd "{'aa'}" }'
++f'{1: abcd "{"aa"}" }'
+ f'{1=: "abcd {'aa'}}'
+-f'{x:a{z:hy "user"}} \'\'\''
++f"{x:a{z:hy \"user\"}} '''"
+ 
+ # Changing the outer quotes is fine because the format-spec is in a nested expression.
+-f'{f'{z=:hy "user"}'} \'\'\''
++f"{f'{z=:hy "user"}'} '''"
+ 
+ 
+ #  We have to be careful about changing the quotes if the f-string has a debug expression because it is inserted verbatim.
+ f'{1=: "abcd \'\'}'  # Don't change the outer quotes, or it results in a syntax error
+-f'{1=: abcd \'\'}'  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
+-f'{1=: abcd \"\"}'  # Changing the quotes here is fine because the inner quotes are escaped
++f"{1=: abcd \'\'}"  # Changing the quotes here is fine because the inner quotes aren't the opposite quotes
++f"{1=: abcd \"\"}"  # Changing the quotes here is fine because the inner quotes are escaped
+ # Don't change the quotes in the following cases:
+ f'{x=:hy "user"} \'\'\''
+ f'{x=:a{y:hy "user"}} \'\'\''
+@@ -42,4 +42,4 @@
+ 
+ f"""{1=: "this" is fine}"""
+ f"""{1=: "this" is fine}"""  # Change quotes to double quotes because they're preferred
+-f'{1=: {'ab"cd"'}}'  # It's okay if the quotes are in an expression part.
++f"{1=: {'ab"cd"'}}"  # It's okay if the quotes are in an expression part.
 ```

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

@@ -326,6 +326,13 @@ assert False, "Implicit concatenated stringuses {} layout on {} format"[
 assert False, +"Implicit concatenated string" "uses {} layout on {} format".format(
     "Multiline", "first"
 )
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+
+"a" f'{1=: "abcd \'\'}'
+f'{1=: "abcd \'\'}' "a"
+f'{1=: "abcd \'\'}' f"{1=: 'abcd \"\"}"
 ```
 
 ## Outputs
@@ -733,4 +740,11 @@ assert False, "Implicit concatenated stringuses {} layout on {} format"[
 assert False, +"Implicit concatenated stringuses {} layout on {} format".format(
     "Multiline", "first"
 )
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/13935
+
+f'a{1=: "abcd \'\'}'
+f'{1=: "abcd \'\'}a'
+f'{1=: "abcd \'\'}' f"{1=: 'abcd \"\"}"
 ```