Better skip_file behavior for streams

isort/api.py

@@ -125,6 +125,7 @@ def sort_stream(
     file_path: Optional[Path] = None,
     disregard_skip: bool = False,
     show_diff: Union[bool, TextIO] = False,
+    raise_on_skip: bool = True,
     **config_kwargs,
 ) -> bool:
     """Sorts any imports within the provided code stream, outputs to the provided output stream.
@@ -150,6 +151,7 @@ def sort_stream(
             config=config,
             file_path=file_path,
             disregard_skip=disregard_skip,
+            raise_on_skip=raise_on_skip,
             **config_kwargs,
         )
         _output_stream.seek(0)
@@ -187,6 +189,7 @@ def sort_stream(
             _internal_output,
             extension=extension or (file_path and file_path.suffix.lstrip(".")) or "py",
             config=config,
+            raise_on_skip=raise_on_skip,
         )
     except FileSkipComment:
         raise FileSkipComment(content_source)

isort/core.py

@@ -30,6 +30,7 @@ def process(
     input_stream: TextIO,
     output_stream: TextIO,
     extension: str = "py",
+    raise_on_skip: bool = True,
     config: Config = DEFAULT_CONFIG,
 ) -> bool:
     """Parses stream identifying sections of contiguous imports and sorting them
@@ -61,6 +62,7 @@ def process(
     first_import_section: bool = True
     indent: str = ""
     isort_off: bool = False
+    skip_file: bool = False
     code_sorting: Union[bool, str] = False
     code_sorting_section: str = ""
     code_sorting_indent: str = ""
@@ -149,7 +151,11 @@ def process(
 
             for file_skip_comment in FILE_SKIP_COMMENTS:
                 if file_skip_comment in line:
-                    raise FileSkipComment("Passed in content")
+                    if raise_on_skip:
+                        raise FileSkipComment("Passed in content")
+                    else:
+                        isort_off = True
+                        skip_file = True
 
             if not in_quote and stripped_line == "# isort: off":
                 isort_off = True
@@ -195,7 +201,7 @@ def process(
             not_imports = bool(in_quote) or was_in_quote or in_top_comment or isort_off
             if not (in_quote or was_in_quote or in_top_comment):
                 if isort_off:
-                    if stripped_line == "# isort: on":
+                    if not skip_file and stripped_line == "# isort: on":
                         isort_off = False
                 elif stripped_line.endswith("# isort: split"):
                     not_imports = True

isort/main.py

@@ -1089,6 +1089,7 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
                 show_diff=show_diff,
                 file_path=file_path,
                 extension=ext_format,
+                raise_on_skip=False,
             )
     elif "/" in file_names and not allow_root:
         printer = create_terminal_printer(color=config.color_output)

tests/unit/test_main.py

@@ -918,6 +918,31 @@ def test_unsupported_encodings(tmpdir, capsys):
     out, error = capsys.readouterr()
 
 
+def test_stream_skip_file(tmpdir, capsys):
+    input_with_skip = """
+# isort: skip_file
+import b
+import a
+"""
+    stream_with_skip = as_stream(input_with_skip)
+    main.main(["-"], stdin=stream_with_skip)
+    out, error = capsys.readouterr()
+    assert out == input_with_skip
+
+    input_without_skip = input_with_skip.replace("isort: skip_file", "generic comment")
+    stream_without_skip = as_stream(input_without_skip)
+    main.main(["-"], stdin=stream_without_skip)
+    out, error = capsys.readouterr()
+    assert (
+        out
+        == """
+# generic comment
+import a
+import b
+"""
+    )
+
+
 def test_only_modified_flag(tmpdir, capsys):
     # ensures there is no verbose output for correct files with only-modified flag