Make --diff usable with --check

This follows black's behaviour.

.gersemirc.example

@@ -1,4 +1,4 @@
-# yaml-language-server: $schema=https://raw.githubusercontent.com/BlankSpruce/gersemi/0.19.0/gersemi/configuration.schema.json
+# yaml-language-server: $schema=https://raw.githubusercontent.com/BlankSpruce/gersemi/0.19.1/gersemi/configuration.schema.json
 
 definitions: []
 disable_formatting: false

CHANGELOG.md

@@ -1,4 +1,8 @@
 # Changelog
+## [0.19.1] 2025-02-14
+### Fixed
+- Make `--diff` usable with `--check`. (#58)
+
 ## [0.19.0] 2025-02-10
 ### Added
 - Add `--warnings-as-errors`. (#57)

README.md

@@ -36,9 +36,10 @@ positional arguments:
 modes:
   -c, --check           Check if files require reformatting. Return 0 when there's
                         nothing to reformat. Return 1 when some files would be
-                        reformatted.
+                        reformatted. It can be used together with --diff.
   -i, --in-place        Format files in-place.
-  --diff                Show diff on stdout for each formatted file instead.
+  --diff                Show diff on stdout for each formatted file instead. It can be
+                        used together with --check.
   --print-config {minimal,verbose,default}
                         Print configuration for files. With "minimal" prints source of
                         outcome configuration (configuration file or defaults) and the
@@ -134,7 +135,7 @@ You can use gersemi with a pre-commit hook by adding the following to `.pre-comm
 ```yaml
 repos:
 - repo: https://github.com/BlankSpruce/gersemi
-  rev: 0.19.0
+  rev: 0.19.1
   hooks:
   - id: gersemi
 ```
@@ -150,7 +151,7 @@ If you want to use extensions with pre-commit list them with [`additional_depend
 ```yaml
 repos:
 - repo: https://github.com/BlankSpruce/gersemi
-  rev: 0.19.0
+  rev: 0.19.1
   hooks:
   - id: gersemi
     additional_dependencies:

gersemi/__main__.py

@@ -68,6 +68,7 @@ def create_argparser():
     Check if files require reformatting.
     Return {SUCCESS} when there's nothing to reformat.
     Return {FAIL} when some files would be reformatted.
+    It can be used together with --diff.
             """,
     )
     modes_group.add_argument(
@@ -81,7 +82,10 @@ def create_argparser():
         "--diff",
         dest="show_diff",
         action="store_true",
-        help="Show diff on stdout for each formatted file instead.",
+        help="""
+    Show diff on stdout for each formatted file instead.
+    It can be used together with --check.
+        """,
     )
     modes_group.add_argument(
         "--print-config",

gersemi/__version__.py

@@ -4,4 +4,4 @@
 __license__ = "MPL 2.0"
 __title__ = "gersemi"
 __url__ = "https://github.com/BlankSpruce/gersemi"
-__version__ = "0.19.0"
+__version__ = "0.19.1"

gersemi/mode.py

@@ -7,9 +7,12 @@ class Mode(Enum):
     CheckFormatting = 2
     ShowDiff = 3
     PrintConfig = 4
+    CheckFormattingAndShowDiff = 5
 
 
 def get_mode(args) -> Mode:
+    if args.check_formatting and args.show_diff:
+        return Mode.CheckFormattingAndShowDiff
     if args.show_diff:
         return Mode.ShowDiff
     if args.check_formatting:

gersemi/runner.py

@@ -37,11 +37,12 @@
 from gersemi.return_codes import FAIL, INTERNAL_ERROR, SUCCESS
 from gersemi.task_result import TaskResult
 from gersemi.tasks.check_formatting import check_formatting
+from gersemi.tasks.check_and_show_diff import check_and_show_diff
 from gersemi.tasks.do_nothing import do_nothing
 from gersemi.tasks.forward_to_stdout import forward_to_stdout
 from gersemi.tasks.format_file import format_file
 from gersemi.tasks.rewrite_in_place import rewrite_in_place
-from gersemi.tasks.show_diff import show_colorized_diff, show_diff
+from gersemi.tasks.show_diff import show_diff
 from gersemi.utils import fromfile, smart_open
 from gersemi.keywords import Keywords
 from gersemi.warnings import UnknownCommandWarning
@@ -58,11 +59,16 @@ class WarningSink:
     def __init__(self, quiet):
         self.quiet = quiet
         self.at_least_one_warning_issued = False
+        self.records = []
 
-    def __call__(self, *args, **kwargs):
+    def __call__(self, s: str):
         self.at_least_one_warning_issued = True
         if not self.quiet:
-            print_to_stderr(*args, **kwargs)
+            self.records.append(s)
+
+    def flush(self):
+        for s in self.records:
+            print_to_stderr(s)
 
 
 class StatusCode:
@@ -162,13 +168,14 @@ def find_all_custom_command_definitions(
 
 def select_task(mode: Mode, configuration: Configuration):
     return {
-        Mode.ForwardToStdout: lambda _: forward_to_stdout,
-        Mode.RewriteInPlace: lambda _: rewrite_in_place,
-        Mode.CheckFormatting: lambda _: check_formatting,
-        Mode.ShowDiff: lambda config: (
-            show_colorized_diff if config.control.color else show_diff
+        Mode.ForwardToStdout: forward_to_stdout,
+        Mode.RewriteInPlace: rewrite_in_place,
+        Mode.CheckFormatting: check_formatting,
+        Mode.ShowDiff: partial(show_diff, configuration.control.color),
+        Mode.CheckFormattingAndShowDiff: partial(
+            check_and_show_diff, configuration.control.color
         ),
-    }[mode](configuration)
+    }[mode]
 
 
 def run_task(
@@ -257,7 +264,11 @@ def split_files_by_formatting_state(
 def store_files_in_cache(
     mode: Mode, cache, configuration_summary: str, files: Iterable[Path]
 ) -> None:
-    if mode in [Mode.CheckFormatting, Mode.RewriteInPlace]:
+    if mode in [
+        Mode.CheckFormatting,
+        Mode.CheckFormattingAndShowDiff,
+        Mode.RewriteInPlace,
+    ]:
         cache.store_files(configuration_summary, files)
 
 
@@ -335,7 +346,7 @@ def __init__(
         self.warning_sink = warning_sink
 
     def _warn(self, item: NotSupportedKeys, text: str):
-        self.warning_sink(f"{item.path}:", text)
+        self.warning_sink(f"{item.path}: {text}")
 
     def _inform_about_not_supported_keys(self, item: NotSupportedKeys):
         if item.path in self.processed_configuration_files:
@@ -442,4 +453,5 @@ def run(args: argparse.Namespace):
             if (control.warnings_as_errors and warning_sink.at_least_one_warning_issued)
             else SUCCESS
         )
+        warning_sink.flush()
         return status_code.value

gersemi/tasks/check_and_show_diff.py

@@ -0,0 +1,12 @@
+from gersemi.formatted_file import FormattedFile
+from gersemi.task_result import TaskResult
+from gersemi.tasks.check_formatting import check_formatting
+from gersemi.tasks.show_diff import get_diff
+
+
+def check_and_show_diff(
+    should_colorize: bool, formatted_file: FormattedFile
+) -> TaskResult:
+    result = check_formatting(formatted_file)
+    result.to_stdout = get_diff(should_colorize, formatted_file)
+    return result

gersemi/tasks/show_diff.py

@@ -1,5 +1,4 @@
 from difflib import unified_diff
-from typing import Iterator
 from gersemi.formatted_file import FormattedFile
 from gersemi.return_codes import SUCCESS
 from gersemi.task_result import TaskResult
@@ -29,29 +28,23 @@ def colorize(diff):
         yield from diff
 
 
-def get_diff(formatted_file: FormattedFile) -> Iterator[str]:
-    return unified_diff(
+def get_diff(should_colorize: bool, formatted_file: FormattedFile) -> str:
+    result = unified_diff(
         a=f"{formatted_file.before}\n".splitlines(keepends=True),
         b=f"{formatted_file.after}\n".splitlines(keepends=True),
         fromfile=fromfile(formatted_file.path),
         tofile=tofile(formatted_file.path),
         n=5,
     )
+    if should_colorize:
+        result = colorize(result)
+    return "".join(result)
 
 
-def show_diff(formatted_file: FormattedFile) -> TaskResult:
+def show_diff(should_colorize: bool, formatted_file: FormattedFile) -> TaskResult:
     return TaskResult(
         path=formatted_file.path,
         return_code=SUCCESS,
-        to_stdout="".join(get_diff(formatted_file)),
-        warnings=formatted_file.warnings,
-    )
-
-
-def show_colorized_diff(formatted_file: FormattedFile) -> TaskResult:
-    return TaskResult(
-        path=formatted_file.path,
-        return_code=SUCCESS,
-        to_stdout="".join(colorize(get_diff(formatted_file))),
+        to_stdout=get_diff(should_colorize, formatted_file),
         warnings=formatted_file.warnings,
     )

tests/test_executable.py

@@ -81,7 +81,32 @@ def test_check_on_formatted_file_should_return_zero(app, testfiles):
 
 
 def test_check_on_not_formatted_file_should_return_one(app, testfiles):
-    assert app("--check", testfiles / "not_formatted_file.cmake") == fail()
+    target = (testfiles / "not_formatted_file.cmake").resolve()
+    assert app("--check", target) == fail(
+        stdout="",
+        stderr=f"""{target} would be reformatted
+""",
+    )
+
+
+def test_diff_on_not_formatted_files_should_return_zero(app, testfiles):
+    target = testfiles / "directory_with_not_formatted_files"
+    assert app("--diff", target) == success(stdout=match_not(""), stderr="")
+
+
+def test_check_with_diff_on_not_formatted_files_should_return_one(app, testfiles):
+    target = testfiles / "directory_with_not_formatted_files"
+    file1 = (target / "file1.cmake").resolve()
+    file2 = (target / "file2.cmake").resolve()
+    file3 = (target / "file3.cmake").resolve()
+
+    assert app("--check", "--diff", target) == fail(
+        stdout=match_not(""),
+        stderr=f"""{file1} would be reformatted
+{file2} would be reformatted
+{file3} would be reformatted
+""",
+    )
 
 
 def test_format_file_in_place(app, testfiles):