Add hook to check the number of allowed lines

README.md

@@ -58,6 +58,11 @@ Attempts to load all json files to verify syntax.
 #### `check-merge-conflict`
 Check for files that contain merge conflict strings.
 
+#### `check-number-of-lines-count`
+Check if number of lines of a file is greater than a threshold. You can
+configure this with the following commandline option:
+  - `--max-lines N` - maximum number of lines allowed in a file.
+
 #### `check-shebang-scripts-are-executable`
 Checks that scripts with shebangs are executable.
 

pre_commit_hooks/check_number_of_lines_count.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+import argparse
+from typing import Optional
+from typing import Sequence
+
+
+def main(argv: Optional[Sequence[str]] = None) -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*')
+    parser.add_argument(
+        '--max-lines',
+        default=30,
+        type=int,
+        action='store',
+        help='Maximum allowable number of lines (default: 30)',
+    )
+    args = parser.parse_args(argv)
+
+    retcode = 0
+    for filename in args.filenames:
+        with open(filename) as file:
+            file_content = file.readlines()
+            number_of_lines = len(file_content)
+            if number_of_lines > args.max_lines:
+                print(
+                    f'{filename} ({number_of_lines} lines) exceeds '
+                    f'{args.max_lines} lines.',
+                )
+                retcode = 1
+
+    return retcode
+
+
+if __name__ == '__main__':
+    exit(main())

setup.cfg

@@ -43,6 +43,7 @@ console_scripts =
     check-executables-have-shebangs = pre_commit_hooks.check_executables_have_shebangs:main
     check-json = pre_commit_hooks.check_json:main
     check-merge-conflict = pre_commit_hooks.check_merge_conflict:main
+    check-number-of-lines-count = check_number_of_lines_count:main
     check-shebang-scripts-are-executable = pre_commit_hooks.check_shebang_scripts_are_executable:main
     check-symlinks = pre_commit_hooks.check_symlinks:main
     check-toml = pre_commit_hooks.check_toml:main

tests/check_number_of_lines_count_test.py

@@ -0,0 +1,31 @@
+from pre_commit_hooks.check_number_of_lines_count import main
+
+
+def test_number_of_lines_count_bad(tmpdir):
+    max_lines = 30
+    line_contents = []
+    filename = tmpdir.join('lines_count_bad')
+
+    for line_number in range(max_lines + 1):
+        line_contents.append(f'I am the {line_number+1}. line!')
+
+    with open(filename, 'w') as file:
+        file.write('\n'.join(line_contents))
+
+    ret = main([str(filename), f'--max-lines={max_lines}'])
+    assert ret == 1
+
+
+def test_number_of_lines_count_good(tmpdir):
+    max_lines = 30
+    line_contents = []
+    filename = tmpdir.join('lines_count_good')
+
+    for line_number in range(max_lines):
+        line_contents.append(f'I am the {line_number+1}. line!')
+
+    with open(filename, 'w') as file:
+        file.write('\n'.join(line_contents))
+
+    ret = main([str(filename), f'--max-lines={max_lines}'])
+    assert ret == 0