[scout] fix playwright configs discovery script and add save flag for CI (#213147)

## Summary

This PR fixes the search logic to look for playwright configs in all
possible & expected locations (`src/*` was not working), matching one of
3 regexp:
```
      /(x-pack\/platform\/plugins\/(?:private|shared|[^\/]+)\/([^\/]+))\/ui_tests\//,
      /(x-pack\/solutions\/[^\/]+\/plugins\/([^\/]+))\/ui_tests\//,
      /(src\/platform\/plugins\/(?:private|shared)?\/?([^\/]+))\/ui_tests\//,
```

For each plugin we also have `usesParallelWorkers` prop (`true` if at
least 1 config runs with concurrent workers) to decide later, if we need
worker with 4 or 8 VCPUs.

The idea is to run `node scripts/scout discover-playwright-configs
--save` on CI and use generated json as source to build test run
pipeline.

Current output:

```
{
  "discover_enhanced": {
    "group": "platform",
    "pluginPath": "x-pack/platform/plugins/private/discover_enhanced",
    "configs": [
      "x-pack/platform/plugins/private/discover_enhanced/ui_tests/parallel.playwright.config.ts",
      "x-pack/platform/plugins/private/discover_enhanced/ui_tests/playwright.config.ts"
    ],
    "usesParallelWorkers": true
  },
  "maps": {
    "group": "platform",
    "pluginPath": "x-pack/platform/plugins/shared/maps",
    "configs": [
      "x-pack/platform/plugins/shared/maps/ui_tests/playwright.config.ts"
    ],
    "usesParallelWorkers": false
  },
  "observability_onboarding": {
    "group": "observability",
    "pluginPath": "x-pack/solutions/observability/plugins/observability_onboarding",
    "configs": [
      "x-pack/solutions/observability/plugins/observability_onboarding/ui_tests/parallel.playwright.config.ts",
      "x-pack/solutions/observability/plugins/observability_onboarding/ui_tests/playwright.config.ts"
    ],
    "usesParallelWorkers": true
  }
}
```

src/platform/packages/shared/kbn-scout/src/cli/config_discovery.ts

@@ -7,7 +7,10 @@
  * License v3.0 only", or the "Server Side Public License, v 1".
  */
 
+import fs from 'fs';
 import { Command } from '@kbn/dev-cli-runner';
+import { SCOUT_OUTPUT_ROOT } from '@kbn/scout-info';
+import { resolve } from 'path';
 import { getScoutPlaywrightConfigs, DEFAULT_TEST_PATH_PATTERNS } from '../config';
 import { measurePerformance } from '../common';
 
@@ -21,29 +24,41 @@ export const discoverPlaywrightConfigs: Command<void> = {
 
   Common usage:
     node scripts/scout discover-playwright-configs --searchPaths <search_paths>
+    node scripts/scout discover-playwright-configs --save
     node scripts/scout discover-playwright-configs
   `,
   flags: {
     string: ['searchPaths'],
-    default: { searchPaths: DEFAULT_TEST_PATH_PATTERNS },
+    boolean: ['save'],
+    default: { searchPaths: DEFAULT_TEST_PATH_PATTERNS, save: false },
   },
   run: ({ flagsReader, log }) => {
     const searchPaths = flagsReader.arrayOfStrings('searchPaths')!;
 
-    const plugins = measurePerformance(log, 'Discovering playwright config files', () => {
+    const pluginsMap = measurePerformance(log, 'Discovering playwright config files', () => {
       return getScoutPlaywrightConfigs(searchPaths, log);
     });
 
     const finalMessage =
-      plugins.size === 0
-        ? 'No playwright config files found'
-        : `Found playwright config files in '${plugins.size}' plugins`;
+      pluginsMap.size === 0
+        ? 'No Playwright config files found'
+        : `Found Playwright config files in '${pluginsMap.size}' plugins`;
+
+    if (pluginsMap.size > 0 && flagsReader.boolean('save')) {
+      const scoutConfigsFilePath = resolve(SCOUT_OUTPUT_ROOT, 'scout_playwright_configs.json');
+      fs.writeFileSync(
+        scoutConfigsFilePath,
+        JSON.stringify(Object.fromEntries(pluginsMap), null, 2)
+      );
+      log.info(`${finalMessage}. Saved to '${scoutConfigsFilePath}'`);
+      return;
+    }
 
     log.info(finalMessage);
 
-    plugins.forEach((files, plugin) => {
-      log.info(`[${plugin}] plugin:`);
-      files.forEach((file) => {
+    pluginsMap.forEach((data, plugin) => {
+      log.info(`${data.group} / [${plugin}] plugin:`);
+      data.configs.map((file) => {
         log.info(`- ${file}`);
       });
     });

src/platform/packages/shared/kbn-scout/src/config/discovery/search_configs.test.ts

@@ -35,21 +35,36 @@ describe('getScoutPlaywrightConfigs', () => {
 
   it('should correctly extract plugin names and group config files', () => {
     (fastGlob.sync as jest.Mock).mockReturnValue([
-      'x-pack/platform/plugins/plugin_a/ui_tests/playwright.config.ts',
-      'x-pack/platform/plugins/plugin_a/ui_tests/parallel.playwright.config.ts',
+      'x-pack/platform/plugins/private/plugin_a/ui_tests/playwright.config.ts',
+      'x-pack/platform/plugins/private/plugin_a/ui_tests/parallel.playwright.config.ts',
       'x-pack/solutions/security/plugins/plugin_b/ui_tests/playwright.config.ts',
+      'src/platform/plugins/shared/plugin_c/ui_tests/playwright.config.ts',
     ]);
 
-    const plugins = getScoutPlaywrightConfigs(['x-pack/'], mockLog);
+    const plugins = getScoutPlaywrightConfigs(['x-pack/', 'src/'], mockLog);
 
-    expect(plugins.size).toBe(2);
-    expect(plugins.get('plugin_a')).toEqual([
-      'x-pack/platform/plugins/plugin_a/ui_tests/playwright.config.ts',
-      'x-pack/platform/plugins/plugin_a/ui_tests/parallel.playwright.config.ts',
-    ]);
-    expect(plugins.get('plugin_b')).toEqual([
-      'x-pack/solutions/security/plugins/plugin_b/ui_tests/playwright.config.ts',
-    ]);
+    expect(plugins.size).toBe(3);
+    expect(plugins.get('plugin_a')).toEqual({
+      configs: [
+        'x-pack/platform/plugins/private/plugin_a/ui_tests/playwright.config.ts',
+        'x-pack/platform/plugins/private/plugin_a/ui_tests/parallel.playwright.config.ts',
+      ],
+      usesParallelWorkers: true,
+      group: 'platform',
+      pluginPath: 'x-pack/platform/plugins/private/plugin_a',
+    });
+    expect(plugins.get('plugin_b')).toEqual({
+      configs: ['x-pack/solutions/security/plugins/plugin_b/ui_tests/playwright.config.ts'],
+      usesParallelWorkers: false,
+      group: 'security',
+      pluginPath: 'x-pack/solutions/security/plugins/plugin_b',
+    });
+    expect(plugins.get('plugin_c')).toEqual({
+      configs: ['src/platform/plugins/shared/plugin_c/ui_tests/playwright.config.ts'],
+      usesParallelWorkers: false,
+      group: 'platform',
+      pluginPath: 'src/platform/plugins/shared/plugin_c',
+    });
   });
 
   it('should log a warning if a file path does not match the expected pattern', () => {

src/platform/packages/shared/kbn-scout/src/config/discovery/search_configs.ts

@@ -13,35 +13,78 @@ import { ToolingLog } from '@kbn/tooling-log';
 
 export const DEFAULT_TEST_PATH_PATTERNS = ['src/platform/plugins', 'x-pack/**/plugins'];
 
+interface PluginScoutConfig {
+  group: string;
+  pluginPath: string;
+  usesParallelWorkers: boolean;
+  configs: string[];
+}
+
 export const getScoutPlaywrightConfigs = (searchPaths: string[], log: ToolingLog) => {
   const patterns = searchPaths.map((basePath) =>
     path.join(basePath, '**/ui_tests/{playwright.config.ts,parallel.playwright.config.ts}')
   );
 
-  log.info('Searching for playwright config files in the following paths:');
+  log.info('Searching for Playwright config files in the following paths:');
   patterns.forEach((pattern) => log.info(`- ${pattern}`));
   log.info(''); // Add a newline for better readability
 
   const files = patterns.flatMap((pattern) => fastGlob.sync(pattern, { onlyFiles: true }));
 
-  // Group config files by plugin
-  const plugins = files.reduce((acc: Map<string, string[]>, filePath: string) => {
-    const match = filePath.match(
-      /(?:src\/platform\/plugins|x-pack\/.*?\/plugins)\/(?:.*?\/)?([^\/]+)\/ui_tests\//
-    );
-    const pluginName = match ? match[1] : null;
+  const typeMappings: Record<string, string> = {
+    'x-pack/solutions/security': 'security',
+    'x-pack/solutions/search': 'search',
+    'x-pack/solutions/observability': 'observability',
+    'x-pack/platform/plugins': 'platform',
+    'src/platform/plugins': 'platform',
+  };
 
-    if (pluginName) {
-      if (!acc.has(pluginName)) {
-        acc.set(pluginName, []);
+  const matchPluginPath = (filePath: string): { pluginPath: string; pluginName: string } | null => {
+    const regexes = [
+      /(x-pack\/platform\/plugins\/(?:private|shared|[^\/]+)\/([^\/]+))\/ui_tests\//,
+      /(x-pack\/solutions\/[^\/]+\/plugins\/([^\/]+))\/ui_tests\//,
+      /(src\/platform\/plugins\/(?:private|shared)?\/?([^\/]+))\/ui_tests\//,
+    ];
+
+    for (const regex of regexes) {
+      const match = filePath.match(regex);
+      if (match) {
+        return { pluginPath: match[1], pluginName: match[2] };
       }
-      acc.get(pluginName)!.push(filePath);
-    } else {
+    }
+    return null;
+  };
+
+  const pluginsWithConfigs = new Map<string, PluginScoutConfig>();
+
+  files.forEach((filePath) => {
+    const matchResult = matchPluginPath(filePath);
+    if (!matchResult) {
       log.warning(`Unable to extract plugin name from path: ${filePath}`);
+      return;
     }
 
-    return acc;
-  }, new Map<string, string[]>());
+    const { pluginPath, pluginName } = matchResult;
+    const group =
+      Object.entries(typeMappings).find(([key]) => filePath.includes(key))?.[1] || 'unknown';
 
-  return plugins;
+    if (!pluginsWithConfigs.has(pluginName)) {
+      pluginsWithConfigs.set(pluginName, {
+        group,
+        pluginPath,
+        configs: [],
+        usesParallelWorkers: false,
+      });
+    }
+
+    const pluginData = pluginsWithConfigs.get(pluginName)!;
+    if (!pluginData.configs.includes(filePath)) {
+      pluginData.configs.push(filePath);
+      if (filePath.endsWith('parallel.playwright.config.ts')) {
+        pluginData.usesParallelWorkers = true;
+      }
+    }
+  });
+
+  return pluginsWithConfigs;
 };