feat(fvm): Support v3 config file

lib/modules/manager/fvm/extract.spec.ts

@@ -23,7 +23,7 @@ describe('modules/manager/fvm/extract', () => {
       ).toBeNull();
     });
 
-    it('returns a result', () => {
+    it('returns a result for .fvm/fvm_config.json', () => {
       const res = extractPackageFile(
         '{"flutterSdkVersion": "2.10.1", "flavors": {}}',
         packageFile,
@@ -38,7 +38,19 @@ describe('modules/manager/fvm/extract', () => {
       ]);
     });
 
-    it('supports non range', () => {
+    it('returns a result for .fvmrc', () => {
+      const res = extractPackageFile('{"flutter": "2.10.1"}', packageFile);
+      expect(res?.deps).toEqual([
+        {
+          currentValue: '2.10.1',
+          datasource: 'flutter-version',
+          depName: 'flutter',
+          packageName: 'flutter/flutter',
+        },
+      ]);
+    });
+
+    it('supports non range for .fvm/fvm_config.json', () => {
       const res = extractPackageFile(
         '{"flutterSdkVersion": "stable", "flavors": {}}',
         packageFile,
@@ -52,5 +64,17 @@ describe('modules/manager/fvm/extract', () => {
         },
       ]);
     });
+
+    it('supports non range for .fvmrc', () => {
+      const res = extractPackageFile('{"flutter": "stable"}', packageFile);
+      expect(res?.deps).toEqual([
+        {
+          currentValue: 'stable',
+          datasource: 'flutter-version',
+          depName: 'flutter',
+          packageName: 'flutter/flutter',
+        },
+      ]);
+    });
   });
 });

lib/modules/manager/fvm/extract.ts

@@ -1,38 +1,33 @@
-import is from '@sindresorhus/is';
 import { logger } from '../../../logger';
+import { Json } from '../../../util/schema-utils';
 import { FlutterVersionDatasource } from '../../datasource/flutter-version';
 import type { PackageDependency, PackageFileContent } from '../types';
-
-interface FvmConfig {
-  flutterSdkVersion: string;
-}
+import { FvmConfig } from './schema';
 
 export function extractPackageFile(
   content: string,
   packageFile: string,
 ): PackageFileContent | null {
-  let fvmConfig: FvmConfig;
+  let flutterVersion: string | undefined;
   try {
-    fvmConfig = JSON.parse(content);
+    const config = Json.pipe(FvmConfig).parse(content);
+    flutterVersion = config.flutter ?? config.flutterSdkVersion;
+
+    if (!flutterVersion) {
+      logger.debug(
+        { contents: config },
+        'FVM config does not have a flutter version specified',
+      );
+      return null;
+    }
   } catch (err) {
     logger.debug({ packageFile, err }, 'Invalid FVM config');
     return null;
   }
 
-  if (!fvmConfig.flutterSdkVersion) {
-    logger.debug(
-      { contents: fvmConfig },
-      'FVM config does not have flutterSdkVersion specified',
-    );
-    return null;
-  } else if (!is.string(fvmConfig.flutterSdkVersion)) {
-    logger.debug({ contents: fvmConfig }, 'flutterSdkVersion must be a string');
-    return null;
-  }
-
   const dep: PackageDependency = {
     depName: 'flutter',
-    currentValue: fvmConfig.flutterSdkVersion,
+    currentValue: flutterVersion,
     datasource: FlutterVersionDatasource.id,
     packageName: 'flutter/flutter',
   };

lib/modules/manager/fvm/index.ts

@@ -6,6 +6,6 @@ export { extractPackageFile } from './extract';
 export const supportedDatasources = [FlutterVersionDatasource.id];
 
 export const defaultConfig = {
-  fileMatch: ['(^|/)\\.fvm/fvm_config\\.json$'],
+  fileMatch: ['(^|/)\\.fvm/fvm_config\\.json$', '(^|/)\\.fvmrc$'],
   versioning: semverVersioning.id,
 };

lib/modules/manager/fvm/readme.md

@@ -1 +1 @@
-Keeps the `.fvm/fvm_config.json` file updated.
+Keeps the `.fvmrc` file or older `.fvm/fvm_config.json` file updated.

lib/modules/manager/fvm/schema.ts

@@ -0,0 +1,7 @@
+import { z } from 'zod';
+
+export const FvmConfig = z.object({
+  flutterSdkVersion: z.string().optional(),
+  flutter: z.string().optional(),
+});
+export type FvmConfig = z.infer<typeof FvmConfig>;