Join implicit concatenated strings when they fit on a line (#13663)

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string.options.json

@@ -0,0 +1,5 @@
+[
+  {
+    "preview": "enabled"
+  }
+]

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string.py

@@ -0,0 +1,321 @@
+"aaaaaaaaa" "bbbbbbbbbbbbbbbbbbbb" # Join
+
+(
+    "aaaaaaaaaaa" "bbbbbbbbbbbbbbbb"
+) # join
+
+
+(
+    "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
+) # too long to join
+
+
+"different '" 'quote "are fine"' # join
+
+# More single quotes
+"one single'" "two 'single'" ' two "double"'
+
+# More double quotes
+'one double"' 'two "double"' " two 'single'"
+
+# Equal number of single and double quotes
+'two "double"' " two 'single'"
+
+f"{'Hy \"User\"'}" 'more'
+
+b"aaaaaaaaa" b"bbbbbbbbbbbbbbbbbbbb" # Join
+
+(
+    b"aaaaaaaaaaa" b"bbbbbbbbbbbbbbbb"
+) # join
+
+
+(
+    b"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" b"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
+) # too long to join
+
+
+# Skip joining if there is a trailing comment
+(
+    "fffffffffffff"
+    "bbbbbbbbbbbbb" # comment
+    "cccccccccccccc"
+)
+
+# Skip joining if there is a leading comment
+(
+    "fffffffffffff"
+    # comment
+    "bbbbbbbbbbbbb"
+    "cccccccccccccc"
+)
+
+
+##############################################################################
+# F-strings
+##############################################################################
+
+# Escape `{` and `}` when marging an f-string with a string
+"a {not_a_variable}" f"b {10}" "c"
+
+# Join, and break expressions
+f"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa{
+expression
+}bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb" f"cccccccccccccccccccc {20999}" "more"
+
+# Join, but don't break the expressions
+f"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa{expression}bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb" f"cccccccccccccccccccc {20999}" "more"
+
+f"test{
+expression
+}flat" f"can be {
+joined
+} together"
+
+aaaaaaaaaaa = f"test{
+expression
+}flat" f"cean beeeeeeee {
+joined
+} eeeeeeeeeeeeeeeeeeeeeeeeeeeee" # inline
+
+
+f"single quoted '{x}'" f'double quoted "{x}"' # Same number of quotes => use preferred quote style
+f"single quote ' {x}" f'double quoted "{x}"'  # More double quotes => use single quotes
+f"single quoted '{x}'" f'double quote " {x}"'  # More single quotes => use double quotes
+
+# Different triple quoted strings
+f"{'''test'''}" f'{"""other"""}'
+
+# Now with inner quotes
+f"{'''test ' '''}" f'{"""other " """}'
+f"{some_where_nested('''test ' ''')}" f'{"""other " """ + "more"}'
+f"{b'''test ' '''}" f'{b"""other " """}'
+f"{f'''test ' '''}" f'{f"""other " """}'
+
+# debug expressions containing quotes
+f"{10 + len('bar')=}" f"{10 + len('bar')=}"
+f"{10 + len('bar')=}" f'no debug{10}' f"{10 + len('bar')=}"
+
+# We can't savely merge this pre Python 3.12 without altering the debug expression.
+f"{10 + len('bar')=}" f'{10 + len("bar")=}'
+
+
+##############################################################################
+# Don't join raw strings
+##############################################################################
+
+r"a" "normal"
+R"a" "normal"
+
+f"test" fr"test"
+f"test" fR"test"
+
+
+##############################################################################
+# Don't join triple quoted strings
+##############################################################################
+
+"single" """triple"""
+
+"single" f""""single"""
+
+b"single" b"""triple"""
+
+
+##############################################################################
+# Join strings in with statements
+##############################################################################
+
+# Fits
+with "aa" "bbb" "cccccccccccccccccccccccccccccccccccccccccccccc":
+    pass
+
+# Parenthesize single-line
+with "aa" "bbb" "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc":
+    pass
+
+# Multiline
+with "aa" "bbb" "cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc":
+    pass
+
+with f"aaaaaaa{expression}bbbb" f"ccc {20999}" "more":
+    pass
+
+
+##############################################################################
+# For loops
+##############################################################################
+
+# Flat
+for a in "aaaaaaaaa" "bbbbbbbbb" "ccccccccc" "dddddddddd":
+    pass
+
+# Parenthesize single-line
+for a in "aaaaaaaaa" "bbbbbbbbb" "ccccccccc" "dddddddddd" "eeeeeeeeeeeeeee" "fffffffffffff" "ggggggggggggggg" "hh":
+    pass
+
+# Multiline
+for a in "aaaaaaaaa" "bbbbbbbbb" "ccccccccc" "dddddddddd" "eeeeeeeeeeeeeee" "fffffffffffff" "ggggggggggggggg" "hhhh":
+    pass
+
+##############################################################################
+# Assert statement
+##############################################################################
+
+# Fits
+assert "aaaaaaaaa" "bbbbbbbbbbbb", "cccccccccccccccc" "dddddddddddddddd"
+
+# Wrap right
+assert "aaaaaaaaa" "bbbbbbbbbbbb", "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffff"
+
+# Right multiline
+assert "aaaaaaaaa" "bbbbbbbbbbbb", "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffffffff" "ggggggggggggg" "hhhhhhhhhhh"
+
+# Wrap left
+assert "aaaaaaaaa" "bbbbbbbbbbbb" "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffffffff", "ggggggggggggg" "hhhhhhhhhhh"
+
+# Left multiline
+assert "aaaaaaaaa" "bbbbbbbbbbbb" "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffffffff" "ggggggggggggg", "hhhhhhhhhhh"
+
+# wrap both
+assert "aaaaaaaaa" "bbbbbbbbbbbb" "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffffffff", "ggggggggggggg" "hhhhhhhhhhh" "iiiiiiiiiiiiiiiiii" "jjjjjjjjjjjjj" "kkkkkkkkkkkkkkkkk" "llllllllllll"
+
+# both multiline
+assert "aaaaaaaaa" "bbbbbbbbbbbb" "cccccccccccccccc" "dddddddddddddddd" "eeeeeeeeeeeee" "fffffffffffffff" "ggggggggggggg", "hhhhhhhhhhh" "iiiiiiiiiiiiiiiiii" "jjjjjjjjjjjjj" "kkkkkkkkkkkkkkkkk" "llllllllllll" "mmmmmmmmmmmmmm"
+
+
+##############################################################################
+# In clause headers (can_omit_optional_parentheses)
+##############################################################################
+# Use can_omit_optional_parentheses layout to avoid an instability where the formatter
+# picks the can_omit_optional_parentheses layout when the strings are joined.
+if (
+    f"implicit"
+    "concatenated"
+    "string" + f"implicit"
+               "concaddddddddddded"
+               "ring"
+    * len([aaaaaa, bbbbbbbbbbbbbbbb, cccccccccccccccccc, ddddddddddddddddddddddddddd])
+):
+    pass
+
+# Keep parenthesizing multiline - implicit concatenated strings
+if (
+    f"implicit"
+    """concatenate
+    d"""
+    "string" + f"implicit"
+               "concaddddddddddded"
+               "ring"
+    * len([aaaaaa, bbbbbbbbbbbbbbbb, cccccccccccccccccc, ddddddddddddddddddddddddddd])
+):
+    pass
+
+if (
+    [
+        aaaaaa,
+        bbbbbbbbbbbbbbbb,
+        cccccccccccccccccc,
+        ddddddddddddddddddddddddddd,
+    ]
+    + "implicitconcat"
+      "enatedstriiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing"
+):
+    pass
+
+
+# In match statements
+match x:
+    case "implicitconcat" "enatedstring" | [
+        aaaaaa,
+        bbbbbbbbbbbbbbbb,
+        cccccccccccccccccc,
+        ddddddddddddddddddddddddddd,
+    ]:
+        pass
+
+    case [
+            aaaaaa,
+            bbbbbbbbbbbbbbbb,
+            cccccccccccccccccc,
+            ddddddddddddddddddddddddddd,
+        ] | "implicitconcat" "enatedstring" :
+        pass
+
+    case "implicitconcat" "enatedstriiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing" | [
+        aaaaaa,
+        bbbbbbbbbbbbbbbb,
+        cccccccccccccccccc,
+        ddddddddddddddddddddddddddd,
+    ]:
+        pass
+
+
+##############################################################################
+# In docstring positions
+##############################################################################
+
+def short_docstring():
+    "Implicit" "concatenated" "docstring"
+
+def long_docstring():
+    "Loooooooooooooooooooooong" "doooooooooooooooooooocstriiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing" "exceding the line width" "but it should be concatenated anyways because it is single line"
+
+def docstring_with_leading_whitespace():
+    "    This is a " "implicit" "concatenated" "docstring"
+
+def docstring_with_trailing_whitespace():
+    "This is a " "implicit" "concatenated" "docstring    "
+
+def docstring_with_leading_empty_parts():
+    "       " "   " "" "This is a " "implicit" "concatenated" "docstring"
+
+def docstring_with_trailing_empty_parts():
+    "This is a " "implicit" "concatenated" "docstring" ""   "  " "           "
+
+def all_empty():
+    "          " "       " " "
+
+def byte_string_in_docstring_position():
+    b"  don't trim the" b"bytes literal "
+
+def f_string_in_docstring_position():
+    f"  don't trim the" "f-string literal "
+
+def single_quoted():
+    ' content\ ' '     '
+    return
+
+def implicit_with_comment():
+    (
+        "a"
+        # leading
+        "the comment above"
+    )
+
+##############################################################################
+# Regressions
+##############################################################################
+
+LEEEEEEEEEEEEEEEEEEEEEEFT = RRRRRRRRIIIIIIIIIIIIGGGGGHHHT | {
+    "entityNameeeeeeeeeeeeeeeeee",  # comment must be long enough to
+    "some long implicit concatenated string" "that should join"
+}
+
+# Ensure that flipping between Multiline and BestFit layout results in stable formatting
+# when using IfBreaksParenthesized layout.
+assert False, "Implicit concatenated string" "uses {} layout on {} format".format(
+    "Multiline", "first"
+)
+
+assert False, await "Implicit concatenated string" "uses {} layout on {} format".format(
+    "Multiline", "first"
+)
+
+assert False, "Implicit concatenated stringuses {} layout on {} format"[
+    aaaaaaaaa, bbbbbb
+]
+
+assert False, +"Implicit concatenated string" "uses {} layout on {} format".format(
+    "Multiline", "first"
+)

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string_assignment.options.json

@@ -0,0 +1,5 @@
+[
+  {
+    "preview": "enabled"
+  }
+]

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string_assignment.py

@@ -0,0 +1,293 @@
+## Implicit concatenated strings with a trailing comment but a non splittable target.
+
+# Don't join the string because the joined string with the inlined comment exceeds the line length limit.
+____aaa = (
+    "aaaaaaaaaaaaaaaaaaaaa" "aaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvvvvvv"
+)  # c
+
+# This is the same string as above and should lead to the same formatting. The only difference is that we start
+# with an unparenthesized string.
+____aaa = "aaaaaaaaaaaaaaaaaaaaa" "aaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvvvvvv"  # c
+
+# Again the same string as above but this time as non-implicit concatenated string.
+# It's okay if the formatting differs because it's an explicit choice to use implicit concatenation.
+____aaa = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvvvvvv"  # c
+
+# Join the string because it's exactly in the line length limit when the comment is inlined.
+____aaa = (
+    "aaaaaaaaaaaaaaaaaaa" "aaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvv"
+)  # c
+
+# This is the same string as above and should lead to the same formatting. The only difference is that we start
+# with an unparenthesized string.
+____aaa = "aaaaaaaaaaaaaaaaaaa" "aaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvv"  # c
+
+# Again the same string as above but as a non-implicit concatenated string. It should result in the same formatting
+# (for consistency).
+____aaa = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvvvvvvvvvvv"  # c
+
+# It should collapse the parentheses if the joined string and the comment fit on the same line.
+# This is required for stability.
+____aaa = (
+    "aaaaaaaaaaaaaaaaaaaaa" "aaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbvv"  # c
+)
+
+
+#############################################################
+# Assignments where the target or annotations are splittable
+#############################################################
+
+
+# The target splits because of a magic trailing comma
+# The string is joined and not parenthesized because it just fits into the line length (including comment).
+a[
+    aaaaaaa,
+    b,
+] = "ccccccccccccccccccccccccccccc" "cccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+# Same but starting with a joined string. They should both result in the same formatting.
+[
+    aaaaaaa,
+    b,
+] = "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+# The target splits because of the magic trailing comma
+# The string is **not** joined because it with the inlined comment exceeds the line length limit.
+a[
+    aaaaaaa,
+    b,
+] = "ccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+
+# The target should be flat
+# The string should be joined because it fits into the line length
+a[
+    aaaaaaa,
+    b
+] = (
+    "ccccccccccccccccccccccccccccccccccc" "cccccccccccccccccccccccc"  # comment
+)
+
+# Same but starting with a joined string. They should both result in the same formatting.
+a[
+    aaaaaaa,
+    b
+] = "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+# The target should be flat
+# The string gets parenthesized because it, with the inlined comment, exceeds the line length limit.
+a[
+    aaaaaaa,
+    b
+] = "ccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+
+# Split an overlong target, but join the string if it fits
+a[
+    aaaaaaa,
+    b
+].bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    "ccccccccccccccccccccccccccccccccccccccccc" "cccccccccccccccccccccccccccccc"  # comment
+)
+
+# Split both if necessary and keep multiline
+a[
+    aaaaaaa,
+    b
+].bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    "ccccccccccccccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccc"  # comment
+)
+
+#########################################################
+# Leading or trailing own line comments:
+# Preserve the parentheses
+########################################################
+a[
+    aaaaaaa,
+    b
+] = (
+    # test
+    "ccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"
+)
+
+a[
+    aaaaaaa,
+    b
+] = (
+    "ccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"
+    # test
+)
+
+a[
+    aaaaaaa,
+    b
+] = (
+    "ccccccccccccccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"
+    # test
+)
+
+
+#############################################################
+# Type alias statements
+#############################################################
+
+# First break the right, join the string
+type A[str, int, number] = "Literal[string, int] | None | " "CustomType" "| OtherCustomTypeExcee"  # comment
+
+# Keep multiline if overlong
+type A[str, int, number] = "Literal[string, int] | None | " "CustomTypeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"  # comment
+
+# Break the left if it is over-long, join the string
+type Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa[stringgggggggggg, inttttttttttttttttttttttt, number] = "Literal[string, int] | None | " "CustomType"  # comment
+
+# Break both if necessary and keep multiline
+type Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa[stringgggggggggg, inttttttttttttttttttttttt, number] = "Literal[string, int] | None | " "CustomTypeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"  # comment
+
+
+#############################################################
+# F-Strings
+#############################################################
+
+# Flatten and join the f-string
+aaaaaaaaaaa = f"test{
+expression}flat" f"cean beeeeeeee {joined} eeeeeeeeeeeeeeeee" # inline
+
+# Parenthesize the value and join it, inline the comment
+aaaaaaaaaaa = f"test{
+expression}flat" f"cean beeeeeeee {joined} eeeeeeeeeeeeeeeeeeeeeeeeeee" # inline
+
+# Parenthesize the f-string and keep it multiline because it doesn't fit on a single line including the comment
+aaaaaaaaaaa = f"test{
+expression
+}flat" f"cean beeeeeeee {
+joined
+} eeeeeeeeeeeeeeeeeeeeeeeeeeeee" # inline
+
+
+# The target splits because of a magic trailing comma
+# The string is joined and not parenthesized because it just fits into the line length (including comment).
+a[
+    aaaaaaa,
+    b,
+] = f"ccccc{
+expression}ccccccccccc" f"cccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+
+# Same but starting with a joined string. They should both result in the same formatting.
+[
+    aaaaaaa,
+    b,
+] = f"ccccc{
+expression}ccccccccccccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+# The target splits because of the magic trailing comma
+# The string is **not** joined because it with the inlined comment exceeds the line length limit.
+a[
+    aaaaaaa,
+    b,
+] = f"ccccc{
+expression}cccccccccccccccccccc" f"cccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+
+# The target should be flat
+# The string should be joined because it fits into the line length
+a[
+    aaaaaaa,
+    b
+] = (
+    f"ccccc{
+    expression}ccccccccccc" "cccccccccccccccccccccccc"  # comment
+)
+
+# Same but starting with a joined string. They should both result in the same formatting.
+a[
+    aaaaaaa,
+    b
+] = f"ccccc{
+expression}ccccccccccccccccccccccccccccccccccc"  # comment
+
+# The target should be flat
+# The string gets parenthesized because it, with the inlined comment, exceeds the line length limit.
+a[
+    aaaaaaa,
+    b
+] = f"ccccc{
+expression}ccccccccccc" "ccccccccccccccccccccccccccccccccccccccccccc"  # comment
+
+
+# Split an overlong target, but join the string if it fits
+a[
+    aaaaaaa,
+    b
+].bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    f"ccccc{
+    expression}ccccccccccc" "cccccccccccccccccccccccccccccc"  # comment
+)
+
+# Split both if necessary and keep multiline
+a[
+    aaaaaaa,
+    b
+].bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    f"ccccc{
+    expression}cccccccccccccccccccccccccccccccc" "ccccccccccccccccccccccccccccccc"  # comment
+)
+
+# Don't inline f-strings that contain expressions that are guaranteed to split, e.b. because of a magic trailing comma
+aaaaaaaaaaaaaaaaaa = f"testeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee{
+[a,]
+}" "moreeeeeeeeeeeeeeeeeeee" "test" # comment
+
+aaaaaaaaaaaaaaaaaa = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee{
+[a,]
+}" "moreeeeeeeeeeeeeeeeeeee" "test" # comment
+)
+
+aaaaa[aaaaaaaaaaa] = f"testeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee{
+[a,]
+}" "moreeeeeeeeeeeeeeeeeeee" "test" # comment
+
+aaaaa[aaaaaaaaaaa] = (f"testeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee{
+[a,]
+}" "moreeeeeeeeeeeeeeeeeeee" "test" # comment
+)
+
+# Don't inline f-strings that contain commented expressions
+aaaaaaaaaaaaaaaaaa = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{[
+        a  # comment
+    ]}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+aaaaa[aaaaaaaaaaa] = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{[
+        a  # comment
+    ]}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+# Don't inline f-strings with multiline debug expressions:
+aaaaaaaaaaaaaaaaaa = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{
+    a=}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+aaaaaaaaaaaaaaaaaa = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{a +
+    b=}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+aaaaaaaaaaaaaaaaaa = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{a
+    =}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+aaaaa[aaaaaaaaaaa] = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{
+    a=}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)
+
+aaaaa[aaaaaaaaaaa] = (
+    f"testeeeeeeeeeeeeeeeeeeeeeeeee{a
+    =}" "moreeeeeeeeeeeeeeeeeetest"  # comment
+)

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string_preserve.options.json

@@ -0,0 +1,11 @@
+[
+  {
+    "quote_style": "preserve",
+    "preview": "enabled"
+  },
+  {
+    "quote_style": "preserve",
+    "preview": "enabled",
+    "target_version": "py312"
+  }
+]

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/join_implicit_concatenated_string_preserve.py

@@ -0,0 +1,13 @@
+a = "different '" 'quote "are fine"'  # join
+
+# More single quotes
+"one single'" "two 'single'" ' two "double"'
+
+# More double quotes
+'one double"' 'two "double"' " two 'single'"
+
+# Equal number of single and double quotes
+'two "double"' " two 'single'"
+
+# Already invalid Pre Python 312
+f"{'Hy "User"'}" f'{"Hy 'User'"}'