Added tests of house rules hook.

tools/clangtidy/README.md

@@ -9,7 +9,8 @@ run-clang-tidy -p out/clang-tidy -j 10 -quiet <files>
 Both runners ship with LLVM, under `share/clang`. Needs clang-tidy 20 or
 newer: an older one ignores `CustomFunctions` without a word.
 
-The commit hook, once per clone, submodules included:
+The commit hook, once per clone, submodules included; its tests run with
+`python3 tools/rules/test_hook.py`:
 
 ```bash
 for repo in . $(git config -f .gitmodules --get-regexp path \

tools/rules/test_hook.py

@@ -0,0 +1,258 @@
+#!/usr/bin/env python3
+"""Tests of hook.py: python3 tools/rules/test_hook.py"""
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+HOOK = os.path.join(HERE, "hook.py")
+LICENSE = "/*\nThis file is part of Telegram Desktop,\nthe official desktop"\
+    " application for the Telegram messaging service.\n\nFor license and"\
+    " copyright information please follow this link:\n"\
+    "https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL\n*/\n"
+
+
+def edit(new, old="x", path="/tmp/rules/foo.cpp"):
+    return run({"tool_name": "Edit", "tool_input": {
+        "file_path": path, "old_string": old, "new_string": new}})
+
+
+def write(content, path):
+    return run({"tool_name": "Write", "tool_input": {
+        "file_path": path, "content": content}})
+
+
+def run(payload):
+    done = subprocess.run([sys.executable, HOOK], input=json.dumps(payload),
+        capture_output=True, text=True)
+    return done.returncode, done.stderr
+
+
+class EditHook(unittest.TestCase):
+    def test_one_line_comment_passes(self):
+        self.assertEqual(edit("// the server rejects more\n++count;\n")[0], 0)
+
+    def test_two_line_comment_fails(self):
+        code, why = edit("// the server rejects more,\n// so we stop\nf();\n")
+        self.assertEqual(code, 2)
+        self.assertIn("2-line comment: a comment is one line", why)
+        self.assertIn("// WHY:", why)
+
+    def test_why_block_of_three_passes(self):
+        self.assertEqual(edit("// WHY: a\n// b\n// c\nf();\n")[0], 0)
+
+    def test_why_block_of_four_fails(self):
+        code, why = edit("// WHY: a\n// b\n// c\n// d\nf();\n")
+        self.assertEqual(code, 2)
+        self.assertIn("4-line comment: a // WHY: block runs 3 lines", why)
+
+    def test_why_marker_must_open_the_block(self):
+        self.assertEqual(edit("// a\n// WHY: b\nf();\n")[0], 2)
+
+    def test_commented_out_code_is_a_comment(self):
+        self.assertEqual(edit("//foo();\n//bar();\n//baz();\n")[0], 2)
+
+    def test_block_comment_over_two_lines_fails(self):
+        code, _ = edit("/* the server\n   rejects more */\nf();\n")
+        self.assertEqual(code, 2)
+
+    def test_one_line_block_comment_passes(self):
+        self.assertEqual(edit("/* rejected */ f();\n")[0], 0)
+
+    def test_trailing_comment_opening_a_block_is_one_comment(self):
+        code, _ = edit("f(); /* the server\nrejects more */\n")
+        self.assertEqual(code, 2)
+
+    def test_edit_has_no_budget(self):
+        many = "".join(f"a{i} = {i}; // set a{i}\n" for i in range(6))
+        self.assertEqual(edit(many)[0], 0)
+        self.assertEqual(edit("// one\nf();\n// two\ng();\n")[0], 0)
+
+    def test_moved_block_is_not_new(self):
+        block = "// the server\n// rejects more\n"
+        self.assertEqual(edit(block + "g();\n", old=block + "f();\n")[0], 0)
+
+    def test_harness_is_exempt_from_comment_rules(self):
+        path = "/tmp/Telegram/SourceFiles/test/harness.cpp"
+        self.assertEqual(edit("// a\n// b\n// c\n// d\n", path=path)[0], 0)
+        self.assertEqual(edit("qMin(a, b);\n", path=path)[0], 2)
+
+    def test_banned_function_fails_with_replacement(self):
+        code, why = edit("w = qMin(a, b);\n")
+        self.assertEqual(code, 2)
+        self.assertIn("qMin is banned in this repository -- write std::min",
+            why)
+        self.assertIn("std::clamp", edit("w = qBound(0, v, 9);\n")[1])
+        self.assertIn("std::abs", edit("w = qAbs (v);\n")[1])
+
+    def test_banned_name_inside_identifier_passes(self):
+        self.assertEqual(edit("w = myqMin(a, b) + qMinimum(c);\n")[0], 0)
+
+    def test_banned_name_in_comment_or_string_passes(self):
+        self.assertEqual(edit("// qMin(a, b) was here\n")[0], 0)
+        self.assertEqual(edit('log("qMin(a, b)");\n')[0], 0)
+
+    def test_banned_call_after_url_string_still_fails(self):
+        self.assertEqual(edit('u = "http://x"; v = qMin(a, b);\n')[0], 2)
+
+    def test_untouched_banned_call_on_edited_line_still_fails(self):
+        self.assertEqual(
+            edit("w = qMin(a, b) + 2;\n", old="w = qMin(a, b) + 1;\n")[0], 2)
+
+    def test_non_source_paths_are_ignored(self):
+        self.assertEqual(edit("// a\n// b\n// c\n", path="/tmp/x.py")[0], 0)
+        self.assertEqual(edit("qMin(a, b)\n", path="/tmp/x.style")[0], 0)
+
+    def test_malformed_payload_passes(self):
+        done = subprocess.run([sys.executable, HOOK], input="not json",
+            capture_output=True, text=True)
+        self.assertEqual(done.returncode, 0)
+
+    def test_write_of_new_file_with_license_passes(self):
+        with tempfile.TemporaryDirectory() as folder:
+            path = os.path.join(folder, "new.cpp")
+            code, why = write(LICENSE + "#include \"a.h\"\n\nf();\n", path)
+            self.assertEqual(code, 0, why)
+            code, why = write(LICENSE + "// a\n// b\nf();\n", path)
+            self.assertEqual(code, 2)
+            code, why = write(LICENSE + "// a\nf();\n", path)
+            self.assertEqual(code, 0, why)
+
+    def test_multi_edit_shape_is_read(self):
+        code, why = run({"tool_name": "Edit", "tool_input": {
+            "file_path": "/tmp/rules/foo.cpp",
+            "edits": [{"old_string": "x", "new_string": "qMin(a, b);\n"}]}})
+        self.assertEqual(code, 2)
+
+
+class Repository:
+    def __init__(self):
+        self.folder = tempfile.TemporaryDirectory()
+        self.path = self.folder.name
+        self.git("init", "-q")
+        self.git("config", "user.email", "t@t")
+        self.git("config", "user.name", "t")
+
+    def git(self, *arguments):
+        return subprocess.run(["git", *arguments], cwd=self.path, check=True,
+            capture_output=True, text=True).stdout
+
+    def put(self, files):
+        for name, content in files.items():
+            full = os.path.join(self.path, name)
+            os.makedirs(os.path.dirname(full), exist_ok=True)
+            with open(full, "w", encoding="utf-8") as stream:
+                stream.write(content)
+            self.git("add", name)
+
+    def commit(self, files):
+        self.put(files)
+        self.git("commit", "-q", "-m", "base")
+
+    def staged(self):
+        done = subprocess.run([sys.executable, HOOK, "--staged"],
+            cwd=self.path, capture_output=True, text=True)
+        return done.returncode, done.stderr
+
+
+class StagedHook(unittest.TestCase):
+    def setUp(self):
+        self.repo = Repository()
+        self.repo.commit({"a.cpp": "int a() {\n\treturn 1;\n}\n"})
+
+    def tearDown(self):
+        self.repo.folder.cleanup()
+
+    def stage(self, files):
+        self.repo.put(files)
+        return self.repo.staged()
+
+    def test_two_plain_lines_pass(self):
+        code, why = self.stage({"a.cpp": "// one\nint a() {\n"
+            "\treturn 1; // two\n}\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_third_plain_line_fails(self):
+        code, why = self.stage({"a.cpp": "// one\nint a() {\n"
+            "\t// two\n\treturn 1;\n}\n// three\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("adds 3 comment lines; 2 is the budget", why)
+
+    def test_trailing_comments_count(self):
+        code, why = self.stage({"a.cpp": "int a() {\n\tint b = 1; // b\n"
+            "\tint c = 2; // c\n\treturn b + c; // sum\n}\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("adds 3 comment lines", why)
+
+    def test_closers_and_directives_carry_free_labels(self):
+        code, why = self.stage({"a.cpp": "#ifndef A\n#define A\n"
+            "namespace A {\nint a() {\n\treturn 1; // one\n}\n"
+            "} // namespace A\n#endif // A\n// two\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_moved_comment_is_free(self):
+        self.repo.commit({"a.cpp": "// one\n// two\n// three\nint a() {\n"
+            "\treturn 1;\n}\n"})
+        code, why = self.stage({
+            "a.cpp": "int a() {\n\treturn 1;\n}\n",
+            "b.cpp": "// one\n// two\n// three\nint b() {\n\treturn 2;\n}\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_edited_line_keeps_its_trailing_comment(self):
+        self.repo.commit({"a.cpp": "int a() {\n\treturn 1; // the server\n"
+            "}\n"})
+        code, why = self.stage({"a.cpp": "int a() {\n"
+            "\treturn 2; // the server\n}\n// one\n// two\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("a.cpp:4: a comment is one line", why)
+        self.assertNotIn("budget", why)
+
+    def test_one_why_block_on_top_of_budget(self):
+        code, why = self.stage({"a.cpp": "// one\n\n// two\n\n// three\n\n"
+            "// WHY: a\n// b\n// c\nint a() {\n\treturn 1;\n}\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("adds 3 comment lines", why)
+        code, why = self.stage({"a.cpp": "// one\n\n// two\n\n// WHY: a\n"
+            "// b\n// c\nint a() {\n\treturn 1;\n}\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_second_why_block_fails(self):
+        code, why = self.stage({"a.cpp": "// WHY: a\n// b\nint a() {\n"
+            "\treturn 1;\n}\n// WHY: c\n// d\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("takes 2 // WHY: exceptions; 1 is the budget", why)
+
+    def test_long_block_is_named_by_line(self):
+        code, why = self.stage({"a.cpp": "int a() {\n\treturn 1;\n}\n\n"
+            "// one\n// two\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("a.cpp:5: a comment is one line", why)
+
+    def test_banned_call_is_named_by_line(self):
+        code, why = self.stage({"a.cpp": "int a() {\n\treturn qMax(1, 2);\n"
+            "}\n"})
+        self.assertEqual(code, 1)
+        self.assertIn("a.cpp:2: qMax is banned -- write std::max", why)
+
+    def test_harness_is_exempt_from_comment_rules(self):
+        code, why = self.stage({"Telegram/SourceFiles/test/t.cpp":
+            "// a\n// b\n// c\n// d\nint t() {\n\treturn 1;\n}\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_other_files_are_ignored(self):
+        code, why = self.stage({
+            "t.py": "# a\n# b\n// c\n// d\nqMin(1, 2)\n",
+            "a.style": "// a\n// b\nx: 1px;\n"})
+        self.assertEqual(code, 0, why)
+
+    def test_license_header_of_new_file_is_free(self):
+        code, why = self.stage({"b.cpp": LICENSE + "int b() {\n"
+            "\treturn 2;\n}\n"})
+        self.assertEqual(code, 0, why)
+
+
+if __name__ == "__main__":
+    unittest.main()