Add more study validation from processed_study.cc. (#1183)

Implement additional validation that exists in
[processed_study.cc](https://source.chromium.org/chromium/chromium/src/+/main:components/variations/processed_study.cc;l=38;drc=f9d386e085b36b0118ab74f9a3d6dc18934de430).

Important ones:
* study, experiment, feature name validation
* default_experiment_name validation + experiment existence validation
* experiment param name conflict and emptiness

Other was added just to have the full coverage (forcing_flag,
google_web_experiment_id).

src/seed_tools/README.md

@@ -75,3 +75,17 @@ npm run seed_tools -- split_seed_json <seed_json_path> <output_dir>
 - `<seed_json_path>`: The path to the `seed.json` file to be split.
 - `<output_dir>`: The directory where the individual study files will be
   outputted.
+
+### `validate_seed`
+
+Validates a seed protobuf.
+
+##### Syntax
+
+```bash
+npm run seed_tools -- validate_seed <seed_file>
+```
+
+##### Arguments
+
+- `<seed_file>`: The path to the binary-serialized `seed` protobuf.

src/seed_tools/commands/validate_seed.test.ts

@@ -0,0 +1,55 @@
+// Copyright (c) 2024 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+import * as fs_sync from 'fs';
+import * as path from 'path';
+import { wsPath } from '../../base/path_utils';
+import validate_seed from './validate_seed';
+
+describe('validate_seed command', () => {
+  const testDataDir = wsPath('//src/test/data');
+
+  let errorMock: jest.SpyInstance;
+  let exitMock: jest.SpyInstance;
+
+  beforeEach(async () => {
+    errorMock = jest.spyOn(console, 'error').mockImplementation();
+    exitMock = jest.spyOn(process, 'exit').mockImplementation();
+  });
+
+  afterEach(async () => {
+    jest.restoreAllMocks();
+  });
+
+  describe('valid seeds', () => {
+    const validSeedsDir = path.join(testDataDir, 'valid_seeds');
+    it.each(fs_sync.readdirSync(validSeedsDir))(
+      'correctly validates %s',
+      async (testCase) => {
+        const testCaseDir = path.join(validSeedsDir, testCase);
+        const seedBin = path.join(testCaseDir, 'expected_seed.bin');
+
+        await validate_seed.parseAsync(['node', 'validate_seed', seedBin]);
+
+        expect(errorMock).toHaveBeenCalledTimes(0);
+        expect(exitMock).toHaveBeenCalledWith(0);
+      },
+    );
+  });
+
+  test('invalid seed', async () => {
+    const seedBin = path.join(testDataDir, 'invalid_seed.bin');
+    expect(fs_sync.existsSync(seedBin)).toBe(true);
+
+    await validate_seed.parseAsync(['node', 'validate_seed', seedBin]);
+
+    expect(errorMock).toHaveBeenCalledWith(
+      expect.stringContaining(
+        'Total probability is not 100 for study AllowCertainClientHintsStudy',
+      ),
+    );
+    expect(exitMock).toHaveBeenCalledWith(1);
+  });
+});

src/seed_tools/commands/validate_seed.ts

@@ -0,0 +1,44 @@
+// Copyright (c) 2024 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+import { Command } from '@commander-js/extra-typings';
+import { promises as fs } from 'fs';
+import { VariationsSeed } from '../../proto/generated/variations_seed';
+import * as seed_validation from '../utils/seed_validation';
+import * as study_validation from '../utils/study_validation';
+
+export default new Command('validate_seed')
+  .description('Validates seed.bin')
+  .argument('<seed_file>', 'path to a seed protobuf')
+  .action(main);
+
+async function main(seedFilePath: string) {
+  const variationsSeed = VariationsSeed.fromBinary(
+    await fs.readFile(seedFilePath, { encoding: null }),
+  );
+  const errors = [];
+  for (const study of variationsSeed.study) {
+    const filePath = `${study.name}.json`;
+    for (const error of study_validation.validateStudyReturnErrors(
+      study,
+      filePath,
+    )) {
+      errors.push(error);
+    }
+  }
+
+  for (const error of seed_validation.validateSeedReturnErrors(
+    variationsSeed,
+  )) {
+    errors.push(error);
+  }
+
+  console.log('Seed studies count:', variationsSeed.study.length);
+  if (errors.length > 0) {
+    console.error(`Seed validation errors:\n${errors.join('\n---\n')}`);
+  }
+
+  process.exit(errors.length > 0 ? 1 : 0);
+}

src/seed_tools/seed_tools.ts

@@ -9,6 +9,7 @@ import check_study from './commands/check_study';
 import compare_seeds from './commands/compare_seeds';
 import create_seed from './commands/create_seed';
 import split_seed_json from './commands/split_seed_json';
+import validate_seed from './commands/validate_seed';
 
 program
   .name('seed_tools')
@@ -17,4 +18,5 @@ program
   .addCommand(compare_seeds)
   .addCommand(create_seed)
   .addCommand(split_seed_json)
+  .addCommand(validate_seed)
   .parse();