tests: skip-path-normalization should be a testcase option (#15660)

The "Skip path normalization" option applies to all [out]s of a test
case, so it's more correct for it to be a "case" option rather than an
"out" option.

This also simplifies the parsing of "out" sections' args.

mypy/test/data.py

diff --git a/mypy/test/data.py b/mypy/test/data.py
index 66dafaf..de0267d 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -65,7 +65,6 @@
         join = posixpath.join
 
     out_section_missing = case.suite.required_out_section
-    normalize_output = True
 
     files: list[tuple[str, str]] = []  # path and contents
     output_files: list[tuple[str, str | Pattern[str]]] = []  # output path and contents
@@ -156,8 +155,6 @@
 
             version_check = True
             for arg in args:
-                if arg == "skip-path-normalization":
-                    normalize_output = False
                 if arg.startswith("version"):
                     compare_op = arg[7:9]
                     if compare_op not in {">=", "=="}:
@@ -185,7 +182,7 @@
                         version_check = sys.version_info[: len(version)] == version
             if version_check:
                 tmp_output = [expand_variables(line) for line in item.data]
-                if os.path.sep == "\\" and normalize_output:
+                if os.path.sep == "\\" and case.normalize_output:
                     tmp_output = [fix_win_path(line) for line in tmp_output]
                 if item.id == "out" or item.id == "out1":
                     output = tmp_output
@@ -239,7 +236,6 @@
     case.expected_rechecked_modules = rechecked_modules
     case.deleted_paths = deleted_paths
     case.triggered = triggered or []
-    case.normalize_output = normalize_output
     case.expected_fine_grained_targets = targets
     case.test_modules = test_modules
 
@@ -269,7 +265,7 @@
 
     # Whether or not we should normalize the output to standardize things like
     # forward vs backward slashes in file paths for Windows vs Linux.
-    normalize_output = True
+    normalize_output: bool
 
     # Extra attributes used by some tests.
     last_line: int
@@ -281,10 +277,12 @@
         self,
         parent: DataSuiteCollector,
         suite: DataSuite,
+        *,
         file: str,
         name: str,
         writescache: bool,
         only_when: str,
+        normalize_output: bool,
         platform: str | None,
         skip: bool,
         xfail: bool,
@@ -296,6 +294,7 @@
         self.file = file
         self.writescache = writescache
         self.only_when = only_when
+        self.normalize_output = normalize_output
         if (platform == "windows" and sys.platform != "win32") or (
             platform == "posix" and sys.platform == "win32"
         ):
@@ -651,6 +650,7 @@
     r"(?P<name>[a-zA-Z_0-9]+)"
     r"(?P<writescache>-writescache)?"
     r"(?P<only_when>-only_when_cache|-only_when_nocache)?"
+    r"(?P<skip_path_normalization>-skip_path_normalization)?"
     r"(-(?P<platform>posix|windows))?"
     r"(?P<skip>-skip)?"
     r"(?P<xfail>-xfail)?"
@@ -694,6 +694,7 @@
             platform=m.group("platform"),
             skip=bool(m.group("skip")),
             xfail=bool(m.group("xfail")),
+            normalize_output=not m.group("skip_path_normalization"),
             data=data,
             line=line_no,
         )

test-data/unit/check-literal.test

diff --git a/test-data/unit/check-literal.test b/test-data/unit/check-literal.test
index f63f402..4498b2d 100644
--- a/test-data/unit/check-literal.test
+++ b/test-data/unit/check-literal.test
@@ -278,7 +278,7 @@
 [builtins fixtures/tuple.pyi]
 [out]
 
-[case testLiteralUnicodeWeirdCharacters]
+[case testLiteralUnicodeWeirdCharacters-skip_path_normalization]
 from typing import Any
 from typing_extensions import Literal
 
@@ -334,7 +334,7 @@
 a1 = c3  # E: Incompatible types in assignment (expression has type "Literal['¬b ∧ λ(p)']", variable has type "Literal['\x00¬b ∧ λ(p)']")
 [builtins fixtures/tuple.pyi]
 
-[out skip-path-normalization]
+[out]
 
 [case testLiteralRenamingImportWorks]
 from typing_extensions import Literal as Foo
@@ -478,7 +478,7 @@
 [builtins fixtures/tuple.pyi]
 [out]
 
-[case testLiteralBasicStrUsageSlashes]
+[case testLiteralBasicStrUsageSlashes-skip_path_normalization]
 from typing_extensions import Literal
 
 a: Literal[r"foo\nbar"]
@@ -487,7 +487,7 @@
 reveal_type(a)
 reveal_type(b)
 [builtins fixtures/tuple.pyi]
-[out skip-path-normalization]
+[out]
 main:6: note: Revealed type is "Literal['foo\\nbar']"
 main:7: note: Revealed type is "Literal['foo\nbar']"