test preview cases with line-length 1 unless explicitly skipped (#4087)

* Add new flag for tests, --no-preview-line-length-1, to be used for test cases known to not work in preview mode with line-length=1. Also split out the problematic cases in three cases to separate files. Removed now redundant file which explicitly tested preview annotations with line-length=1

* mode.preview -> preview_mode, mark pep_572_remove_parens as failing with ll1

tests/data/cases/comment_type_hint.py

@@ -0,0 +1,3 @@
+# flags: --no-preview-line-length-1
+# split out from comments2 as it does not work with line-length=1, losing the comment
+a = "type comment with trailing space"  # type: str

tests/data/cases/comments2.py

@@ -155,8 +155,6 @@ def _init_host(self, parsed) -> None:
             pass
 
 
-a = "type comment with trailing space"  # type: str   
-
 #######################
 ### SECTION COMMENT ###
 #######################
@@ -335,8 +333,6 @@ def _init_host(self, parsed) -> None:
             pass
 
 
-a = "type comment with trailing space"  # type: str
-
 #######################
 ### SECTION COMMENT ###
 #######################

tests/data/cases/fmtskip2.py

@@ -1,9 +1,12 @@
+# flags: --no-preview-line-length-1
+# l2 loses the comment with line-length=1 in preview mode
 l1 = ["This list should be broken up", "into multiple lines", "because it is way too long"]
 l2 = ["But this list shouldn't", "even though it also has", "way too many characters in it"]  # fmt: skip
 l3 = ["I have", "trailing comma", "so I should be braked",]
 
 # output
 
+# l2 loses the comment with line-length=1 in preview mode
 l1 = [
     "This list should be broken up",
     "into multiple lines",

tests/data/cases/pep_572_remove_parens.py

@@ -1,4 +1,4 @@
-# flags: --minimum-version=3.8
+# flags: --minimum-version=3.8 --no-preview-line-length-1
 if (foo := 0):
     pass
 

tests/data/cases/preview_hug_parens_with_braces_and_square_brackets.py

@@ -125,23 +125,6 @@ def foo_square_brackets(request):
 func([x for x in "long line long line long line long line long line long line long line"])
 func([x for x in [x for x in "long line long line long line long line long line long line long line"]])
 
-func({"short line"})
-func({"long line", "long long line", "long long long line", "long long long long line", "long long long long long line"})
-func({{"long line", "long long line", "long long long line", "long long long long line", "long long long long long line"}})
-func(("long line", "long long line", "long long long line", "long long long long line", "long long long long long line"))
-func((("long line", "long long line", "long long long line", "long long long long line", "long long long long long line")))
-func([["long line", "long long line", "long long long line", "long long long long line", "long long long long long line"]])
-
-# Do not hug if the argument fits on a single line.
-func({"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"})
-func(("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"))
-func(["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"])
-func(**{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit---"})
-func(*("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit----"))
-array = [{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}]
-array = [("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")]
-array = [["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]]
-
 foooooooooooooooooooo(
     [{c: n + 1 for c in range(256)} for n in range(100)] + [{}], {size}
 )
@@ -151,14 +134,11 @@ def foo_square_brackets(request):
 )
 
 nested_mapping = {"key": [{"a very long key 1": "with a very long value", "a very long key 2": "with a very long value"}]}
-nested_array = [[["long line", "long long line", "long long long line", "long long long long line", "long long long long long line"]]]
 explicit_exploding = [[["short", "line",],],]
 single_item_do_not_explode = Context({
     "version": get_docs_version(),
 })
 
-foo(*["long long long long long line", "long long long long long line", "long long long long long line"])
-
 foo(*[str(i) for i in range(100000000000000000000000000000000000000000000000000000000000)])
 
 foo(
@@ -310,69 +290,6 @@ def foo_square_brackets(request):
     ]
 ])
 
-func({"short line"})
-func({
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-})
-func({{
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-}})
-func((
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-))
-func(((
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-)))
-func([[
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-]])
-
-# Do not hug if the argument fits on a single line.
-func(
-    {"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}
-)
-func(
-    ("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")
-)
-func(
-    ["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]
-)
-func(
-    **{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit---"}
-)
-func(
-    *("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit----")
-)
-array = [
-    {"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}
-]
-array = [
-    ("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")
-]
-array = [
-    ["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]
-]
-
 foooooooooooooooooooo(
     [{c: n + 1 for c in range(256)} for n in range(100)] + [{}], {size}
 )
@@ -387,13 +304,6 @@ def foo_square_brackets(request):
         "a very long key 2": "with a very long value",
     }]
 }
-nested_array = [[[
-    "long line",
-    "long long line",
-    "long long long line",
-    "long long long long line",
-    "long long long long long line",
-]]]
 explicit_exploding = [
     [
         [
@@ -406,12 +316,6 @@ def foo_square_brackets(request):
     "version": get_docs_version(),
 })
 
-foo(*[
-    "long long long long long line",
-    "long long long long long line",
-    "long long long long long line",
-])
-
 foo(*[
     str(i) for i in range(100000000000000000000000000000000000000000000000000000000000)
 ])

tests/data/cases/preview_hug_parens_with_braces_and_square_brackets_no_ll1.py

@@ -0,0 +1,106 @@
+# flags: --preview --no-preview-line-length-1
+# split out from preview_hug_parens_with_brackes_and_square_brackets, as it produces
+# different code on the second pass with line-length 1 in many cases.
+# Seems to be about whether the last string in a sequence gets wrapped in parens or not.
+foo(*["long long long long long line", "long long long long long line", "long long long long long line"])
+func({"short line"})
+func({"long line", "long long line", "long long long line", "long long long long line", "long long long long long line"})
+func({{"long line", "long long line", "long long long line", "long long long long line", "long long long long long line"}})
+func(("long line", "long long line", "long long long line", "long long long long line", "long long long long long line"))
+func((("long line", "long long line", "long long long line", "long long long long line", "long long long long long line")))
+func([["long line", "long long line", "long long long line", "long long long long line", "long long long long long line"]])
+
+
+# Do not hug if the argument fits on a single line.
+func({"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"})
+func(("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"))
+func(["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"])
+func(**{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit---"})
+func(*("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit----"))
+array = [{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}]
+array = [("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")]
+array = [["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]]
+
+nested_array = [[["long line", "long long line", "long long long line", "long long long long line", "long long long long long line"]]]
+
+# output
+
+# split out from preview_hug_parens_with_brackes_and_square_brackets, as it produces
+# different code on the second pass with line-length 1 in many cases.
+# Seems to be about whether the last string in a sequence gets wrapped in parens or not.
+foo(*[
+    "long long long long long line",
+    "long long long long long line",
+    "long long long long long line",
+])
+func({"short line"})
+func({
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+})
+func({{
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+}})
+func((
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+))
+func(((
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+)))
+func([[
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+]])
+
+
+# Do not hug if the argument fits on a single line.
+func(
+    {"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}
+)
+func(
+    ("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")
+)
+func(
+    ["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]
+)
+func(
+    **{"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit---"}
+)
+func(
+    *("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit----")
+)
+array = [
+    {"fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"}
+]
+array = [
+    ("fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line")
+]
+array = [
+    ["fit line", "fit line", "fit line", "fit line", "fit line", "fit line", "fit line"]
+]
+
+nested_array = [[[
+    "long line",
+    "long long line",
+    "long long long line",
+    "long long long long line",
+    "long long long long long line",
+]]]

tests/data/cases/return_annotation_brackets_crash_line_length_1.py

@@ -1,9 +0,0 @@
-# flags: --preview --minimum-version=3.10 --line-length=1
-
-def foo() -> tuple[int, int,]:
-    ...
-# output
-def foo() -> tuple[
-    int,
-    int,
-]: ...

tests/test_format.py

@@ -30,6 +30,7 @@ def check_file(subdir: str, filename: str, *, data: bool = True) -> None:
         fast=args.fast,
         minimum_version=args.minimum_version,
         lines=args.lines,
+        no_preview_line_length_1=args.no_preview_line_length_1,
     )
     if args.minimum_version is not None:
         major, minor = args.minimum_version
@@ -42,6 +43,7 @@ def check_file(subdir: str, filename: str, *, data: bool = True) -> None:
             fast=args.fast,
             minimum_version=args.minimum_version,
             lines=args.lines,
+            no_preview_line_length_1=args.no_preview_line_length_1,
         )
 
 

tests/util.py

@@ -46,6 +46,7 @@ class TestCaseArgs:
     fast: bool = False
     minimum_version: Optional[Tuple[int, int]] = None
     lines: Collection[Tuple[int, int]] = ()
+    no_preview_line_length_1: bool = False
 
 
 def _assert_format_equal(expected: str, actual: str) -> None:
@@ -96,6 +97,7 @@ def assert_format(
     fast: bool = False,
     minimum_version: Optional[Tuple[int, int]] = None,
     lines: Collection[Tuple[int, int]] = (),
+    no_preview_line_length_1: bool = False,
 ) -> None:
     """Convenience function to check that Black formats as expected.
 
@@ -124,20 +126,27 @@ def assert_format(
             f"Black crashed formatting this case in {text} mode."
         ) from e
     # Similarly, setting line length to 1 is a good way to catch
-    # stability bugs. But only in non-preview mode because preview mode
+    # stability bugs. Some tests are known to be broken in preview mode with line length
-    # currently has a lot of line length 1 bugs.
+    # of 1 though, and have marked that with a flag --no-preview-line-length-1
+    preview_modes = [False]
+    if not no_preview_line_length_1:
+        preview_modes.append(True)
+
+    for preview_mode in preview_modes:
+
         try:
             _assert_format_inner(
                 source,
                 None,
-            replace(mode, preview=False, line_length=1),
+                replace(mode, preview=preview_mode, line_length=1),
                 fast=fast,
                 minimum_version=minimum_version,
                 lines=lines,
             )
         except Exception as e:
+            text = "preview" if preview_mode else "non-preview"
             raise FormatFailure(
-            "Black crashed formatting this case with line-length set to 1."
+                f"Black crashed formatting this case in {text} mode with line-length=1."
             ) from e
 
 
@@ -246,6 +255,15 @@ def get_flags_parser() -> argparse.ArgumentParser:
         ),
     )
     parser.add_argument("--line-ranges", action="append")
+    parser.add_argument(
+        "--no-preview-line-length-1",
+        default=False,
+        action="store_true",
+        help=(
+            "Don't run in preview mode with --line-length=1, as that's known to cause a"
+            " crash"
+        ),
+    )
     return parser
 
 
@@ -266,7 +284,11 @@ def parse_mode(flags_line: str) -> TestCaseArgs:
     else:
         lines = []
     return TestCaseArgs(
-        mode=mode, fast=args.fast, minimum_version=args.minimum_version, lines=lines
+        mode=mode,
+        fast=args.fast,
+        minimum_version=args.minimum_version,
+        lines=lines,
+        no_preview_line_length_1=args.no_preview_line_length_1,
     )