fix: doctor for 0.72 Ruby changes

The new release requires support for a range of Ruby version, which are
defined in the project Gemfile. This change add support for validating
against an in project Gemfile (or .ruby-version if it can't find one).
It finally falls back on the baked in version with the CLI.

There are also additional unit tests and some background comments.

packages/cli-doctor/src/commands/doctor.ts

@@ -129,6 +129,7 @@ const doctorCommand = (async (_, options) => {
           }
 
           const {
+            description,
             needsToBeFixed,
             version,
             versions,
@@ -145,7 +146,7 @@ const doctorCommand = (async (_, options) => {
             version,
             versions,
             versionRange,
-            description: healthcheck.description,
+            description: description ?? healthcheck.description,
             runAutomaticFix: getAutomaticFixForPlatform(
               healthcheck,
               process.platform,

packages/cli-doctor/src/tools/envinfo.ts

@@ -33,8 +33,8 @@ async function getEnvironmentInfo(
       System: ['OS', 'CPU', 'Memory', 'Shell'],
       Binaries: ['Node', 'Yarn', 'npm', 'Watchman'],
       IDEs: ['Xcode', 'Android Studio', 'Visual Studio'],
-      Managers: ['CocoaPods', 'RubyGems'],
-      Languages: ['Java'],
+      Managers: ['CocoaPods'],
+      Languages: ['Java', 'Ruby'],
       SDKs: ['iOS SDK', 'Android SDK', 'Windows SDK'],
       npmPackages: packages,
       npmGlobalPackages: ['*react-native*'],

packages/cli-doctor/src/tools/healthchecks/__tests__/ruby.test.ts

@@ -0,0 +1,103 @@
+import ruby, {output} from '../ruby';
+
+//
+// Mocks
+//
+const mockExeca = jest.fn();
+jest.mock('execa', () => mockExeca);
+
+const mockLogger = jest.fn();
+jest.mock('@react-native-community/cli-tools', () => ({
+  findProjectRoot: () => '.',
+  logger: {
+    warn: mockLogger,
+  },
+}));
+
+jest.mock('../../versionRanges', () => ({
+  RUBY: '>= 1.0.0',
+}));
+
+//
+// Placeholder Values
+//
+const Languages = {
+  Ruby: {version: '1.0.0'},
+};
+
+const runRubyGetDiagnostic = () => {
+  // @ts-ignore
+  return ruby.getDiagnostics({Languages});
+};
+
+const Gemfile = {
+  noGemfile: {code: 1},
+  noRuby: {code: 'ENOENT'},
+  ok: {stdout: output.OK},
+  unknown: (err: Error) => err,
+  wrongRuby: (stderr: string) => ({code: 2, stderr}),
+};
+
+//
+// Tests
+//
+
+describe('ruby', () => {
+  beforeEach(() => {
+    mockLogger.mockClear();
+    mockExeca.mockClear();
+  });
+
+  describe('Gemfile', () => {
+    it('validates the environment', async () => {
+      mockExeca.mockResolvedValueOnce(Gemfile.ok);
+
+      expect(await runRubyGetDiagnostic()).toMatchObject({
+        needsToBeFixed: false,
+      });
+    });
+
+    it('fails to find ruby to run the script', async () => {
+      mockExeca.mockRejectedValueOnce(Gemfile.noRuby);
+
+      const resp = await runRubyGetDiagnostic();
+      expect(resp.needsToBeFixed).toEqual(true);
+      expect(resp.description).toMatch(/Ruby/i);
+    });
+
+    it('fails to find the Gemfile and messages the user', async () => {
+      mockExeca.mockRejectedValueOnce(Gemfile.noGemfile);
+
+      const {description} = await runRubyGetDiagnostic();
+      expect(description).toMatch(/could not find/i);
+    });
+
+    it('fails because the wrong version of ruby is installed', async () => {
+      const stderr = '>= 3.2.0, < 3.2.0';
+      mockExeca.mockRejectedValueOnce(Gemfile.wrongRuby(stderr));
+
+      expect(await runRubyGetDiagnostic()).toMatchObject({
+        needsToBeFixed: true,
+        versionRange: stderr,
+      });
+    });
+
+    it('fails for unknown reasons, so we skip it but log', async () => {
+      const error = Error('Something bad went wrong');
+      mockExeca.mockRejectedValueOnce(Gemfile.unknown(error));
+
+      await runRubyGetDiagnostic();
+      expect(mockLogger).toBeCalledTimes(1);
+      expect(mockLogger).toBeCalledWith(error.message);
+    });
+
+    it('uses are static ruby versions builtin into doctor if no Gemfile', async () => {
+      mockExeca.mockRejectedValueOnce(new Error('Meh'));
+      expect(await runRubyGetDiagnostic()).toMatchObject({
+        needsToBeFixed: false,
+        version: Languages.Ruby.version,
+        versionRange: '>= 1.0.0',
+      });
+    });
+  });
+});

packages/cli-doctor/src/tools/healthchecks/common.ts

@@ -104,4 +104,28 @@ function removeMessage(message: string) {
   readline.clearScreenDown(process.stdout);
 }
 
-export {logMessage, logManualInstallation, logError, removeMessage};
+/**
+ * Inline a series of Ruby statements:
+ *
+ * In:
+ *  puts "a"
+ *  puts "b"
+ *
+ * Out:
+ *  puts "a"; puts "b";
+ */
+function inline(
+  strings: TemplateStringsArray,
+  ...values: {toString(): string}[]
+) {
+  const zipped = strings.map((str, i) => `${str}${values[i] ?? ''}`).join('');
+
+  return zipped
+    .trim()
+    .split('\n')
+    .filter((line) => !/^\W*$/.test(line))
+    .map((line) => line.trim())
+    .join('; ');
+}
+
+export {logMessage, logManualInstallation, logError, removeMessage, inline};

packages/cli-doctor/src/tools/healthchecks/ruby.ts

@@ -1,19 +1,174 @@
+import execa from 'execa';
+import chalk from 'chalk';
+
+import {logger, findProjectRoot} from '@react-native-community/cli-tools';
+
 import versionRanges from '../versionRanges';
 import {doesSoftwareNeedToBeFixed} from '../checkInstallation';
 import {HealthCheckInterface} from '../../types';
+import {inline} from './common';
+
+// Exposed for testing only
+export const output = {
+  OK: 'Ok',
+  NO_GEMFILE: 'No Gemfile',
+  NO_RUBY: 'No Ruby',
+  BUNDLE_INVALID_RUBY: 'Bundle invalid Ruby',
+  UNKNOWN: 'Unknown',
+} as const;
+
+// The Change:
+// -----------
+//
+// React Native 0.72 primarily defines the compatible version of Ruby in the
+// project's Gemfile [1]. It does this because it allows for ranges instead of
+// pinning to a version of Ruby.
+//
+// In previous versions the .ruby-version file defined the compatible version,
+// and it was derived in the Gemfile [2]:
+//
+// > ruby File.read(File.join(__dir__, '.ruby-version')).strip
+//
+// Why all of the changes with Ruby?
+// ---------------------------------
+//
+// React Native has had to weigh up a couple of concerns:
+//
+// - Cocoapods: we don't control the minimum supported version, although that
+//   was defined almost a decade ago [3]. Practically system Ruby on macOS works
+//   for our users.
+//
+// - Apple may drop support for scripting language runtimes in future version of
+//   macOS [4]. Ruby 2.7 is effectively EOL, which means many supporting tools and
+//   developer environments _may_ not support it going forward, and 3.0 is becoming
+//   the default in, for example, places like our CI. Some users may be unable to
+//   install Ruby 2.7 on their devices as a matter of policy.
+//
+// - Our Codegen is extensively built in Ruby 2.7.
+//
+// - A common pain-point for users (old and new) setting up their environment is
+//   configuring a Ruby version manager or managing multiple Ruby versions on their
+//   device. This occurs so frequently that we've removed the step from our docs [6]
+//
+// After users suggested bumping Ruby to 3.1.3 [5], a discussion concluded that
+// allowing a range of version of Ruby (>= 2.6.10) was the best way forward. This
+// balanced the need to make the platform easier to start with, but unblocked more
+// sophisticated users.
+//
+// [1] https://github.com/facebook/react-native/pull/36281
+// [2] https://github.com/facebook/react-native/blob/v0.71.3/Gemfile#L4
+// [3] https://github.com/CocoaPods/guides.cocoapods.org/commit/30881800ac2bd431d9c5d7ee74404b13e7f43888
+// [4] https://developer.apple.com/documentation/macos-release-notes/macos-catalina-10_15-release-notes#Scripting-Language-Runtimes
+// [5] https://github.com/facebook/react-native/pull/36074
+// [6] https://github.com/facebook/react-native-website/commit/8db97602347a8623f21e3e516245d04bdf6f1a29
+
+async function checkRubyGemfileRequirement(
+  projectRoot: string,
+): Promise<[string, string?]> {
+  const evaluateGemfile = inline`
+  require "Bundler"
+  gemfile = Bundler::Definition.build("Gemfile", nil, {})
+  version = gemfile.ruby_version.engine_versions.join(", ")
+  begin
+    gemfile.validate_runtime!
+  rescue Bundler::GemfileNotFound
+    puts "${output.NO_GEMFILE}"
+    exit 1
+  rescue Bundler::RubyVersionMismatch
+    puts "${output.BUNDLE_INVALID_RUBY}"
+    STDERR.puts version
+    exit 2
+  rescue => e
+    STDERR e.message
+    exit 3
+  else
+    puts "${output.OK}"
+    STDERR.puts version
+  end`;
+
+  try {
+    await execa('ruby', ['-e', evaluateGemfile], {
+      cwd: projectRoot,
+    });
+    return [output.OK];
+  } catch (e) {
+    switch (e.code) {
+      case 'ENOENT':
+        return [output.NO_RUBY];
+      case 1:
+        return [output.NO_GEMFILE];
+      case 2:
+        return [output.BUNDLE_INVALID_RUBY, e.stderr];
+      default:
+        return [output.UNKNOWN, e.message];
+    }
+  }
+}
 
 export default {
   label: 'Ruby',
   isRequired: false,
   description: 'Required for installing iOS dependencies',
-  getDiagnostics: async ({Managers}) => ({
-    needsToBeFixed: doesSoftwareNeedToBeFixed({
-      version: Managers.RubyGems.version,
+  getDiagnostics: async ({Languages}) => {
+    let projectRoot;
+    try {
+      projectRoot = findProjectRoot();
+    } catch (e) {
+      logger.debug(e.message);
+    }
+
+    const fallbackResult = {
+      needsToBeFixed: doesSoftwareNeedToBeFixed({
+        version: Languages.Ruby.version,
+        versionRange: versionRanges.RUBY,
+      }),
+      version: Languages.Ruby.version,
       versionRange: versionRanges.RUBY,
-    }),
-    version: Managers.RubyGems.version,
-    versionRange: versionRanges.RUBY,
-  }),
+      description: '',
+    };
+
+    // No guidance from the project, so we make the best guess
+    if (!projectRoot) {
+      return fallbackResult;
+    }
+
+    // Gemfile
+    let [code, versionOrError] = await checkRubyGemfileRequirement(projectRoot);
+    switch (code) {
+      case output.OK: {
+        return {
+          needsToBeFixed: false,
+          version: Languages.Ruby.version,
+          versionRange: versionOrError,
+        };
+      }
+      case output.BUNDLE_INVALID_RUBY:
+        return {
+          needsToBeFixed: true,
+          version: Languages.Ruby.version,
+          versionRange: versionOrError,
+        };
+      case output.NO_RUBY:
+        return {
+          needsToBeFixed: true,
+          description: 'Cannot find a working copy of Ruby.',
+        };
+      case output.NO_GEMFILE:
+        fallbackResult.description = `Could not find the project ${chalk.bold(
+          'Gemfile',
+        )} in your project folder (${chalk.dim(
+          projectRoot,
+        )}), guessed using my built-in version.`;
+        break;
+      default:
+        if (versionOrError) {
+          logger.warn(versionOrError);
+        }
+        break;
+    }
+
+    return fallbackResult;
+  },
   runAutomaticFix: async ({loader, logManualInstallation}) => {
     loader.fail();
 

packages/cli-doctor/src/tools/versionRanges.ts

@@ -3,7 +3,7 @@ export default {
   NODE_JS: '>= 16',
   YARN: '>= 1.10.x',
   NPM: '>= 4.x',
-  RUBY: '>= 2.7.6',
+  RUBY: '>= 2.6.10',
   JAVA: '>= 11',
   // Android
   ANDROID_SDK: '>= 31.x',

packages/cli-doctor/src/types.ts

@@ -26,7 +26,6 @@ export type EnvironmentInfo = {
   };
   Managers: {
     CocoaPods: AvailableInformation;
-    RubyGems: AvailableInformation;
   };
   SDKs: {
     'iOS SDK': {
@@ -51,6 +50,7 @@ export type EnvironmentInfo = {
   };
   Languages: {
     Java: Information;
+    Ruby: AvailableInformation;
   };
 };
 
@@ -89,6 +89,7 @@ export type HealthCheckInterface = {
   getDiagnostics: (
     environmentInfo: EnvironmentInfo,
   ) => Promise<{
+    description?: string;
     version?: string;
     versions?: [string];
     versionRange?: string;