Add support for checking only files changed in git

.github/workflows/build.yml

@@ -107,6 +107,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+      with:
+        ref: "${{ github.event.pull_request.head.sha }}"
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
@@ -118,7 +120,9 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        python -m pip install --upgrade build setuptools tox 
+        python -m pip install --upgrade build setuptools tox
     - name: ${{ matrix.tox-env }}
+      env:
+        TOX_MERGE_BASE: "${{ github.event.pull_request.base.sha }}"
       run: |
         python -m tox -e ${{ matrix.tox-env }}

pyproject.toml

@@ -134,12 +134,15 @@ commands=
     {envpython} -m coverage report --show-missing
 
 [testenv:documents]
+passenv = TOX_MERGE_BASE
 deps=
     .
     -r requirements/docs.txt
 commands=
     {envpython} -m mkdocs build --clean --verbose --strict
-    {envpython} -m pyspelling
+    {envpython} -m pyspelling -n python -m {env:TOX_MERGE_BASE:master} -v
+    {envpython} -m pyspelling -n markdown -m {env:TOX_MERGE_BASE:master} -v
+    {envpython} -m pyspelling -n mkdocs -v
 
 [testenv:lint]
 deps=

pyspelling/__init__.py

@@ -5,6 +5,7 @@
 from .__meta__ import __version__, __version_info__  # noqa: F401
 from . import flow_control
 from . import filters
+from .util import git
 from wcmatch import glob
 import codecs
 from collections import namedtuple
@@ -578,7 +579,7 @@ class SpellingTask:
         "O": glob.O
     }
 
-    def __init__(self, checker, config, binary='', verbose=0, jobs=0, debug=False):
+    def __init__(self, checker, config, binary='', verbose=0, jobs=0, git_merge_base='', git_binary=None, debug=False):
         """Initialize."""
 
         if checker == "hunspell":  # pragma: no cover
@@ -594,6 +595,8 @@ def __init__(self, checker, config, binary='', verbose=0, jobs=0, debug=False):
         self.binary = checker if not binary else binary
         self.debug = debug
         self.jobs = jobs
+        self.git_merge_base = git_merge_base
+        self.git_binary = git_binary
 
     def log(self, text, level):
         """Log level."""
@@ -613,11 +616,20 @@ def _to_flags(self, text):
     def walk_src(self, targets, flags, limit):
         """Walk source and parse files."""
 
-        for target in targets:
-            # Glob using `S` for patterns with `|` and `O` to exclude directories.
-            kwargs = {"flags": flags | glob.S | glob.O}
-            kwargs['limit'] = limit
-            yield from glob.iglob(target, **kwargs)
+        # Glob using `S` for patterns with `|` and `O` to exclude directories.
+        kwargs = {"flags": flags | glob.S | glob.O}
+        kwargs['limit'] = limit
+
+        if self.git_merge_base:
+            for target in targets:
+                yield from glob.globfilter(
+                    git.get_file_diff(self.git_merge_base, git_binary=self.git_binary),
+                    target,
+                    **kwargs
+                )
+        else:
+            for target in targets:
+                yield from glob.iglob(target, **kwargs)
 
     def get_checker(self):
         """Get a spell checker object."""
@@ -659,13 +671,18 @@ def run_task(self, task, source_patterns=None):
         glob_flags = self._to_flags(self.task.get('glob_flags', "N|B|G"))
         glob_limit = self.task.get('glob_pattern_limit', 1000)
 
+        if self.git_merge_base:
+            self.log("Searching: Only checking files that changed in git...", 1)
+        else:
+            self.log("Searching: Finding files to check...", 1)
+
         if not source_patterns:
             source_patterns = self.task.get('sources', [])
 
         # If jobs was not specified via command line, check the config for jobs settings
         jobs = max(1, self.config.get('jobs', 1) if self.jobs == 0 else self.jobs)
 
-        expect_match = self.task.get('expect_match', True)
+        expect_match = self.task.get('expect_match', True) and not self.git_merge_base
         if jobs > 1:
             # Use multi-processing to process files concurrently
             with ProcessPoolExecutor(max_workers=jobs) as pool:
@@ -696,7 +713,9 @@ def spellcheck(
     sources=None,
     verbose=0,
     debug=False,
-    jobs=0
+    jobs=0,
+    git_merge_base='',
+    git_binary=None
 ):
     """Spell check."""
 
@@ -737,7 +756,7 @@ def spellcheck(
 
         log('Using {} to spellcheck {}'.format(checker, task.get('name', '')), 1, verbose)
 
-        spelltask = SpellingTask(checker, config, binary, verbose, jobs, debug)
+        spelltask = SpellingTask(checker, config, binary, verbose, jobs, git_merge_base, git_binary, debug)
 
         for result in spelltask.run_task(task, source_patterns=sources):
             log('Context: %s' % result.context, 2, verbose)

pyspelling/__main__.py

@@ -16,6 +16,16 @@ def main():
     group.add_argument('--name', '-n', action='append', help="Specific spelling task by name to run.")
     group.add_argument('--group', '-g', action='append', help="Specific spelling task group to run.")
     parser.add_argument('--binary', '-b', action='store', default='', help="Provide path to spell checker's binary.")
+    parser.add_argument(
+        '--git-merge-base',
+        '-m',
+        help="Specify the git merge base for generating a modified file list."
+    )
+    parser.add_argument(
+        '--git-binary',
+        '-G',
+        help="Specify the path to the the git binary if not on the system path."
+    )
     parser.add_argument(
         '--jobs', '-j',
         action='store',
@@ -44,6 +54,8 @@ def main():
         verbose=args.verbose,
         debug=args.debug,
         jobs=args.jobs,
+        git_merge_base=args.git_merge_base,
+        git_binary=args.git_binary
     )
 
 
@@ -58,6 +70,8 @@ def run(config, **kwargs):
     sources = kwargs.get('sources', [])
     debug = kwargs.get('debug', False)
     jobs = kwargs.get('jobs', 0)
+    git_merge_base = kwargs.get('git_merge_base', '')
+    git_binary = kwargs.get('git_binary', None)
 
     fail = False
     count = 0
@@ -71,6 +85,8 @@ def run(config, **kwargs):
         verbose=verbose,
         debug=debug,
         jobs=jobs,
+        git_merge_base=git_merge_base,
+        git_binary=git_binary
     ):
         count += 1
         if results.error:

pyspelling/util/git.py

@@ -0,0 +1,78 @@
+"""Git support."""
+import subprocess
+import sys
+import os
+
+WIN = sys.platform.startswith('win')
+GIT_BINARY = "git.exe" if WIN else "git"
+
+
+def get_git_tree(target):
+    """Recursively get Git tree."""
+
+    is_file = os.path.isfile(target)
+    folder = os.path.dirname(target) if is_file else target
+    if os.path.exists(os.path.join(folder, ".git")):
+        return folder
+    else:
+        parent = os.path.dirname(folder)
+        if parent == folder:
+            return None
+        else:
+            return get_git_tree(parent)
+
+
+def get_git_dir(tree):
+    """Get Git directory from tree."""
+
+    return os.path.join(tree, ".git")
+
+
+def get_file_diff(target, git_binary=None):
+    """Get the file list of the HEAD vs the specified target."""
+
+    args = ['--no-pager', 'diff', '--name-only', '--cached', '--merge-base', f'{target}']
+    return gitopen(
+        args,
+        git_binary=git_binary,
+        git_tree=get_git_tree(os.path.abspath('.'))
+    ).decode('utf-8').splitlines()
+
+
+def gitopen(args, git_binary=None, git_tree=None):
+    """Call Git with arguments."""
+
+    returncode = output = None
+
+    if git_binary is None or not git_binary:
+        git_binary = GIT_BINARY
+
+    if git_tree is not None:
+        cmd = [git_binary, f"--work-tree={git_tree}", f"--git-dir={get_git_dir(git_tree)}"] + args
+    else:
+        cmd = [git_binary] + args
+
+    if WIN:
+        startupinfo = subprocess.STARTUPINFO()
+        startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
+        process = subprocess.Popen(
+            cmd,
+            startupinfo=startupinfo,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            shell=False
+        )
+    else:
+        process = subprocess.Popen(
+            cmd,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            shell=False,
+        )
+    output = process.communicate()
+    returncode = process.returncode
+
+    if returncode != 0:
+        raise RuntimeError(output[1].decode('utf-8').rstrip())
+
+    return output[0]