Keep long comments off the opening line and within line_length

isort/wrap.py

@@ -19,7 +19,7 @@ def import_statement(
     """Returns a multi-line wrapped form of the provided from import statement."""
     if explode:
         formatter = vertical_hanging_indent
-        line_length = 1
+        line_length = config.wrap_length or config.line_length
         include_trailing_comma = True
     else:
         formatter = formatter_from_string((multi_line_output or config.multi_line_output).name)

isort/wrap_modes.py

@@ -173,8 +173,33 @@ def vertical_hanging_indent(**interface: Any) -> str:
     )
     _imports = ("," + interface["line_separator"] + interface["indent"]).join(interface["imports"])
     _comma_maybe = "," if interface["include_trailing_comma"] else ""
+    opening = f"{interface['statement']}({_line_with_comments}"
+    _is_functional_comment = any(
+        comment.strip().lower().startswith(("noqa", "type: ignore"))
+        for comment in (interface["comments"] or [])
+    )
+    if (
+        _line_with_comments
+        and len(opening) > interface["line_length"]
+        and not _is_functional_comment
+    ):
+        _comment_on_own_line = interface["line_separator"].join(
+            isort.comments.add_to_line(
+                [single_comment],
+                interface["indent"],
+                removed=interface["remove_comments"],
+                comment_prefix=interface["comment_prefix"].lstrip(),
+            )
+            for single_comment in (interface["comments"] or [])
+        )
+        return (
+            f"{interface['statement']}({interface['line_separator']}"
+            f"{_comment_on_own_line}{interface['line_separator']}"
+            f"{interface['indent']}{_imports}{_comma_maybe}"
+            f"{interface['line_separator']})"
+        )
     return (
-        f"{interface['statement']}({_line_with_comments}{interface['line_separator']}"
+        f"{opening}{interface['line_separator']}"
         f"{interface['indent']}{_imports}{_comma_maybe}{interface['line_separator']})"
     )
 

tests/unit/test_regressions.py

@@ -2489,3 +2489,20 @@ def test_add_import_keeps_a_prefixed_module_docstring_first_issue_1893():
                 docstring = f"{cased}{quote}module docstring\n{quote}\n"
                 source = docstring + "import a\n"
                 assert isort.code(source, add_imports=["import a"]) == source, cased + quote
+
+
+def test_comments_should_cause_wrapping_on_long_lines_black_mode_issue_2124():
+    """Ensure isort doesn't merge a long comment onto the opening line of a
+    multiline from import when using the black profile.
+    See: https://github.com/PyCQA/isort/issues/2124
+    """
+    assert isort.code(
+        """from os.path import (
+    join,
+    # this is a really really really really really really really really
+    # really really really really really really long comment
+    getsize,
+)
+""",
+        profile="black",
+    ).startswith("from os.path import (\n    # this is a really really")

tests/unit/test_wrap.py

@@ -93,3 +93,20 @@ def test_star_import_wrapped_end_to_end() -> None:
     source = "from very.very.very.very.very.very.very.very.very.long.line import *\n"
     expected = "from very.very.very.very.very.very.very.very.very.long.line import \\\n    *\n"
     assert code(source, line_length=20, force_single_line=True) == expected
+
+
+def test_import_statement_explode_long_comment_respects_line_length() -> None:
+    """A long comment in explode mode is placed on its own line."""
+    result = wrap.import_statement(
+        import_start="from os.path import ",
+        from_imports=["getsize", "join"],
+        comments=[
+            " this is a really really really really really really really really"
+            " really really really really really really long comment"
+        ],
+        config=Config(profile="black"),
+        explode=True,
+    )
+    lines = result.split("\n")
+    assert lines[0] == "from os.path import ("
+    assert "long comment" in lines[1]

tests/unit/test_wrap_modes.py

@@ -127,6 +127,108 @@ def test_vertical_grid_size_near_line_length(
     )
 
 
+def test_vertical_hanging_indent_long_comment_respects_line_length():
+    """A long comment that exceeds line_length is placed on its own line."""
+    assert (
+        wrap_modes.vertical_hanging_indent(
+            statement="from os.path import ",
+            imports=["getsize", "join"],
+            white_space="    ",
+            indent="    ",
+            line_length=88,
+            comments=[
+                " this is a really really really really really really"
+                " really really really really really really long comment"
+            ],
+            line_separator="\n",
+            comment_prefix="  #",
+            include_trailing_comma=True,
+            remove_comments=False,
+        )
+        == "from os.path import (\n"
+        "    #  this is a really really really really really really really really"
+        " really really really really long comment\n"
+        "    getsize,\n"
+        "    join,\n"
+        ")"
+    )
+
+
+def test_vertical_hanging_indent_short_comment_stays_on_opening_line():
+    """A short comment that fits within line_length stays on the opening line."""
+    assert (
+        wrap_modes.vertical_hanging_indent(
+            statement="from os.path import ",
+            imports=["getsize", "join"],
+            white_space="    ",
+            indent="    ",
+            line_length=88,
+            comments=[" short comment"],
+            line_separator="\n",
+            comment_prefix="  #",
+            include_trailing_comma=True,
+            remove_comments=False,
+        )
+        == "from os.path import (  #  short comment\n    getsize,\n    join,\n)"
+    )
+
+
+def test_vertical_hanging_indent_non_directive_type_comment_moves_off():
+    """A long comment containing 'type:' but not a 'type: ignore' directive moves off."""
+    assert (
+        wrap_modes.vertical_hanging_indent(
+            statement="from os.path import ",
+            imports=["getsize", "join"],
+            white_space="    ",
+            indent="    ",
+            line_length=88,
+            comments=[
+                " check type: int and more really really really really really really"
+                " really really really really really really long comment"
+            ],
+            line_separator="\n",
+            comment_prefix="  #",
+            include_trailing_comma=True,
+            remove_comments=False,
+        )
+        == "from os.path import (\n"
+        "    #  check type: int and more really really really really really really really really"
+        " really really really really long comment\n"
+        "    getsize,\n"
+        "    join,\n"
+        ")"
+    )
+
+
+def test_vertical_hanging_indent_multi_fragment_comments_each_on_own_line():
+    """Each comment fragment renders on its own # line to respect line_length."""
+    result = wrap_modes.vertical_hanging_indent(
+        statement="from os.path import ",
+        imports=["getsize", "join"],
+        white_space="    ",
+        indent="    ",
+        line_length=88,
+        comments=[
+            " this is a really really really really really really really really",
+            " really really really really really really long comment",
+        ],
+        line_separator="\n",
+        comment_prefix="  #",
+        include_trailing_comma=True,
+        remove_comments=False,
+    )
+    assert result == (
+        "from os.path import (\n"
+        "    #  this is a really really really really really really really really\n"
+        "    #  really really really really really really long comment\n"
+        "    getsize,\n"
+        "    join,\n"
+        ")"
+    )
+    for line in result.split("\n"):
+        assert len(line) <= 88, f"line exceeds 88: {line!r}"
+
+
 # This test code was written by the `hypothesis.extra.ghostwriter` module
 # and is provided under the Creative Commons Zero public domain dedication.