storybookjs · JReinhold · Jun 16, 2025 · Jun 18, 2025 · tmeasday · Jun 18, 2025
diff --git a/code/addons/vitest/src/postinstall-logger.ts b/code/addons/vitest/src/postinstall-logger.ts
@@ -1,7 +1,7 @@
+import { isCI } from 'storybook/internal/common';
 import { colors, logger } from 'storybook/internal/node-logger';
 
-const fancy =
-  process.platform !== 'win32' || process.env.CI || process.env.TERM === 'xterm-256color';
+const fancy = process.platform !== 'win32' || isCI || process.env.TERM === 'xterm-256color';
 
 export const step = colors.gray('›');
 export const info = colors.blue(fancy ? 'ℹ' : 'i');

diff --git a/code/addons/vitest/src/postinstall.ts b/code/addons/vitest/src/postinstall.ts
@@ -8,13 +8,13 @@ import {
   extractProperFrameworkName,
   formatFileContent,
   getProjectRoot,
+  isCI,
   loadAllPresets,
   loadMainConfig,
   scanAndTransformFiles,
   serverResolve,
   transformImportFiles,
   validateFrameworkName,
-  versions,
 } from 'storybook/internal/common';
 import { readConfig, writeConfig } from 'storybook/internal/csf-tools';
 import { colors, logger } from 'storybook/internal/node-logger';
@@ -71,7 +71,7 @@ export default async function postInstall(options: PostinstallOptions) {
 
   const hasCustomWebpackConfig = !!config.getFieldNode(['webpackFinal']);
 
-  const isInteractive = process.stdout.isTTY && !process.env.CI;
+  const isInteractive = process.stdout.isTTY && !isCI;
 
   if (info.frameworkPackageName === '@storybook/nextjs' && !hasCustomWebpackConfig) {
     const out =

diff --git a/code/addons/vitest/src/vitest-plugin/index.ts b/code/addons/vitest/src/vitest-plugin/index.ts
@@ -8,6 +8,7 @@ import {
   DEFAULT_FILES_PATTERN,
   getInterpretedFile,
   normalizeStories,
+  optionalEnvToBoolean,
   resolvePathInStorybookCache,
   validateConfigurationFiles,
 } from 'storybook/internal/common';
@@ -123,14 +124,18 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
     },
   } as InternalOptions;
 
-  if (process.env.DEBUG) {
+  if (optionalEnvToBoolean(process.env.DEBUG)) {
     finalOptions.debug = true;
   }
 
   // To be accessed by the global setup file
   process.env.__STORYBOOK_URL__ = finalOptions.storybookUrl;
   process.env.__STORYBOOK_SCRIPT__ = finalOptions.storybookScript;
 
+  // We signal the test runner that we are not running it via Storybook
+  // We are overriding the environment variable to 'true' if vitest runs via @storybook/addon-vitest's backend
+  const isVitestStorybook = optionalEnvToBoolean(process.env.VITEST_STORYBOOK);
+
   const directories = {
     configDir: finalOptions.configDir,
     workingDir: WORKING_DIR,
@@ -210,10 +215,6 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
       //   plugin.name?.startsWith('vitest:browser')
       // )
 
-      // We signal the test runner that we are not running it via Storybook
-      // We are overriding the environment variable to 'true' if vitest runs via @storybook/addon-vitest's backend
-      const vitestStorybook = process.env.VITEST_STORYBOOK ?? 'false';
-
       const testConfig = nonMutableInputConfig.test;
       finalOptions.vitestRoot =
         testConfig?.dir || testConfig?.root || nonMutableInputConfig.root || process.cwd();
@@ -258,7 +259,7 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
             // To be accessed by the setup file
             __STORYBOOK_URL__: finalOptions.storybookUrl,
 
-            VITEST_STORYBOOK: vitestStorybook,
+            VITEST_STORYBOOK: isVitestStorybook ? 'true' : 'false',
             __VITEST_INCLUDE_TAGS__: finalOptions.tags.include.join(','),
             __VITEST_EXCLUDE_TAGS__: finalOptions.tags.exclude.join(','),
             __VITEST_SKIP_TAGS__: finalOptions.tags.skip.join(','),
@@ -286,9 +287,7 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
               getInitialGlobals: () => {
                 const envConfig = JSON.parse(process.env.VITEST_STORYBOOK_CONFIG ?? '{}');
 
-                const shouldRunA11yTests = process.env.VITEST_STORYBOOK
-                  ? (envConfig.a11y ?? false)
-                  : true;
+                const shouldRunA11yTests = isVitestStorybook ? (envConfig.a11y ?? false) : true;
 
                 return {
                   a11y: {
@@ -370,10 +369,10 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
     configureVitest(context) {
       context.vitest.config.coverage.exclude.push('storybook-static');
 
-      const disableTelemetryVar =
-        process.env.STORYBOOK_DISABLE_TELEMETRY &&
-        process.env.STORYBOOK_DISABLE_TELEMETRY !== 'false';
-      if (!core?.disableTelemetry && !disableTelemetryVar) {
+      if (
+        !core?.disableTelemetry &&
+        !optionalEnvToBoolean(process.env.STORYBOOK_DISABLE_TELEMETRY)
+      ) {
         // NOTE: we start telemetry immediately but do not wait on it. Typically it should complete
         // before the tests do. If not we may miss the event, we are OK with that.
         telemetry(
@@ -407,7 +406,7 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
       }
     },
     async transform(code, id) {
-      if (process.env.VITEST !== 'true') {
+      if (!optionalEnvToBoolean(process.env.VITEST)) {
         return code;
       }
 
@@ -431,7 +430,7 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
   // When running tests via the Storybook UI, we need
   // to find the right project to run, thus we override
   // with a unique identifier using the path to the config dir
-  if (process.env.VITEST_STORYBOOK) {
+  if (isVitestStorybook) {
     const projectName = `storybook:${normalize(finalOptions.configDir)}`;
     plugins.push({
       name: 'storybook:workspace-name-override',

diff --git a/code/core/src/cli/bin/index.ts b/code/core/src/cli/bin/index.ts
@@ -1,4 +1,4 @@
-import { getEnvConfig, parseList } from 'storybook/internal/common';
+import { getEnvConfig, optionalEnvToBoolean, parseList } from 'storybook/internal/common';
 import { logTracker, logger } from 'storybook/internal/node-logger';
 import { addToGlobalContext } from 'storybook/internal/telemetry';
 
@@ -22,8 +22,7 @@ const command = (name: string) =>
     .option(
       '--disable-telemetry',
       'Disable sending telemetry data',
-      // default value is false, but if the user sets STORYBOOK_DISABLE_TELEMETRY, it can be true
-      process.env.STORYBOOK_DISABLE_TELEMETRY && process.env.STORYBOOK_DISABLE_TELEMETRY !== 'false'
+      optionalEnvToBoolean(process.env.STORYBOOK_DISABLE_TELEMETRY)
     )
     .option('--debug', 'Get more logs in debug mode', false)
     .option('--enable-crash-reports', 'Enable sending crash reports to telemetry data')
@@ -151,7 +150,7 @@ command('build')
     await build({
       ...options,
       packageJson: pkg,
-      test: !!options.test || process.env.SB_TESTBUILD === 'true',
+      test: !!options.test || optionalEnvToBoolean(process.env.SB_TESTBUILD),
     }).catch(() => process.exit(1));
   });
 

diff --git a/code/core/src/cli/globalSettings.test.ts b/code/core/src/cli/globalSettings.test.ts
@@ -85,16 +85,22 @@ describe('Settings', () => {
       );
     });
 
-    it('throws error if write fails', async () => {
+    it('logs warning if write fails', async () => {
       vi.mocked(fs.writeFile).mockRejectedValue(new Error('Write error'));
 
-      await expect(settings.save()).rejects.toThrow('Unable to save global settings');
+      await expect(settings.save()).resolves.toBeUndefined();
+      expect(console.warn).toHaveBeenCalledWith(
+        'Unable to save global settings file to /test/settings.json\nReason: Write error'
+      );
     });
 
-    it('throws error if directory creation fails', async () => {
+    it('logs warning if directory creation fails', async () => {
       vi.mocked(fs.mkdir).mockRejectedValue(new Error('Directory creation error'));
 
-      await expect(settings.save()).rejects.toThrow('Unable to save global settings');
+      await expect(settings.save()).resolves.toBeUndefined();
+      expect(console.warn).toHaveBeenCalledWith(
+        'Unable to save global settings file to /test/settings.json\nReason: Directory creation error'
+      );
     });
   });
 });
diff --git a/code/core/src/cli/globalSettings.ts b/code/core/src/cli/globalSettings.ts
@@ -2,10 +2,9 @@ import fs from 'node:fs/promises';
 import { homedir } from 'node:os';
 import { dirname, join } from 'node:path';
 
+import { dedent } from 'ts-dedent';
 import { z } from 'zod';
 
-import { SavingGlobalSettingsFileError } from '../server-errors';
-
 const DEFAULT_SETTINGS_PATH = join(homedir(), '.storybook', 'settings.json');
 
 const VERSION = 1;
@@ -71,10 +70,9 @@ export class Settings {
       await fs.mkdir(dirname(this.filePath), { recursive: true });
       await fs.writeFile(this.filePath, JSON.stringify(this.value, null, 2));
     } catch (err) {
-      throw new SavingGlobalSettingsFileError({
-        filePath: this.filePath,
-        error: err,
-      });
+      console.warn(dedent`
+        Unable to save global settings file to ${this.filePath}
+        ${err && `Reason: ${(err as Error).message ?? err}`}`);
     }
   }
 }
diff --git a/code/core/src/common/utils/envs.ts b/code/core/src/common/utils/envs.ts
@@ -67,3 +67,24 @@ export const stringifyProcessEnvs = (raw: Record<string, string>): Record<string
   // envs['process.env'] = JSON.stringify(raw);
   return envs;
 };
+
+export const optionalEnvToBoolean = (input: string | undefined): boolean | undefined => {
+  if (input === undefined) {
+    return undefined;
+  }
+  if (input.toUpperCase() === 'FALSE' || input === '0') {
+    return false;
+  }
+  if (input.toUpperCase() === 'TRUE' || input === '1') {
+    return true;
+  }
+  return Boolean(input);
+};
+
+/**
+ * Consistently determine if we are in a CI environment
+ *
+ * Doing Boolean(process.env.CI) or !process.env.CI is not enough, because users might set CI=false
+ * or CI=0, which would be truthy, and thus return true in those cases.
+ */
+export const isCI = optionalEnvToBoolean(process.env.CI);
diff --git a/code/core/src/core-server/presets/common-preset.ts b/code/core/src/core-server/presets/common-preset.ts
@@ -3,6 +3,7 @@ import { readFile } from 'node:fs/promises';
 import { dirname, isAbsolute, join } from 'node:path';
 
 import type { Channel } from 'storybook/internal/channels';
+import { optionalEnvToBoolean } from 'storybook/internal/common';
 import {
   JsPackageManagerFactory,
   type RemoveAddonOptions,
@@ -171,22 +172,6 @@ export const typescript = () => ({
   },
 });
 
-const optionalEnvToBoolean = (input: string | undefined): boolean | undefined => {
-  if (input === undefined) {
-    return undefined;
-  }
-  if (input.toUpperCase() === 'FALSE') {
-    return false;
-  }
-  if (input.toUpperCase() === 'TRUE') {
-    return true;
-  }
-  if (typeof input === 'string') {
-    return true;
-  }
-  return undefined;
-};
-
 /** This API is used by third-parties to access certain APIs in a Node environment */
 export const experimental_serverAPI = (extension: Record<string, Function>, options: Options) => {
   let removeAddon = removeAddonBase;

diff --git a/code/core/src/core-server/stores/status.ts b/code/core/src/core-server/stores/status.ts
@@ -1,3 +1,4 @@
+import { optionalEnvToBoolean } from '../../common/utils/envs';
 import { createStatusStore } from '../../shared/status-store';
 import { UNIVERSAL_STATUS_STORE_OPTIONS } from '../../shared/status-store';
 import { UniversalStore } from '../../shared/universal-store';
@@ -12,7 +13,7 @@ const statusStore = createStatusStore({
       before it was ready.
       This will be fixed when we do the planned UniversalStore v0.2.
     */
-    leader: process.env.VITEST_CHILD_PROCESS !== 'true',
+    leader: !optionalEnvToBoolean(process.env.VITEST_CHILD_PROCESS),
   }),
   environment: 'server',
 });

diff --git a/code/core/src/core-server/stores/test-provider.ts b/code/core/src/core-server/stores/test-provider.ts
@@ -1,3 +1,4 @@
+import { optionalEnvToBoolean } from '../../common/utils/envs';
 import { createTestProviderStore } from '../../shared/test-provider-store';
 import { UNIVERSAL_TEST_PROVIDER_STORE_OPTIONS } from '../../shared/test-provider-store';
 import { UniversalStore } from '../../shared/universal-store';
@@ -12,7 +13,7 @@ const testProviderStore = createTestProviderStore({
             before it was ready.
             This will be fixed when we do the planned UniversalStore v0.2.
           */
-    leader: process.env.VITEST_CHILD_PROCESS !== 'true',
+    leader: !optionalEnvToBoolean(process.env.VITEST_CHILD_PROCESS),
   }),
 });
 

diff --git a/code/core/src/core-server/withTelemetry.ts b/code/core/src/core-server/withTelemetry.ts
@@ -1,4 +1,4 @@
-import { HandledError, cache, loadAllPresets } from 'storybook/internal/common';
+import { HandledError, cache, isCI, loadAllPresets } from 'storybook/internal/common';
 import { logger } from 'storybook/internal/node-logger';
 import { getPrecedingUpgrade, oneWayHash, telemetry } from 'storybook/internal/telemetry';
 import type { EventType } from 'storybook/internal/telemetry';
@@ -14,7 +14,7 @@ type TelemetryOptions = {
 };
 
 const promptCrashReports = async () => {
-  if (process.env.CI) {
+  if (isCI) {
     return undefined;
   }
 

diff --git a/code/core/src/node-logger/logger/log-tracker.ts b/code/core/src/node-logger/logger/log-tracker.ts
@@ -1,6 +1,8 @@
 import { promises as fs } from 'node:fs';
 import path, { join } from 'node:path';
 
+import { isCI } from 'storybook/internal/common';
+
 import { cleanLog } from '../../../../lib/cli-storybook/src/automigrate/helpers/cleanLog';
 import type { LogLevel } from './logger';
 
@@ -97,7 +99,7 @@ class LogTracker {
     await fs.writeFile(filePath, logContent, 'utf-8');
     this.#logs = [];
 
-    return process.env.CI ? filePath : path.relative(process.cwd(), filePath);
+    return isCI ? filePath : path.relative(process.cwd(), filePath);
   }
 }
 

diff --git a/code/core/src/node-logger/prompts/prompt-config.ts b/code/core/src/node-logger/prompts/prompt-config.ts
@@ -1,3 +1,4 @@
+import { optionalEnvToBoolean } from '../../common/utils/envs';
 import type { PromptProvider } from './prompt-provider-base';
 import { ClackPromptProvider } from './prompt-provider-clack';
 import { PromptsPromptProvider } from './prompt-provider-prompts';
@@ -9,7 +10,9 @@ const PROVIDERS = {
   prompts: new PromptsPromptProvider(),
 } as const;
 
-let currentPromptLibrary: PromptLibrary = process.env.USE_CLACK === 'true' ? 'clack' : 'prompts';
+let currentPromptLibrary: PromptLibrary = optionalEnvToBoolean(process.env.USE_CLACK)
+  ? 'clack'
+  : 'prompts';
 
 export const setPromptLibrary = (library: PromptLibrary): void => {
   currentPromptLibrary = library;

diff --git a/code/core/src/server-errors.ts b/code/core/src/server-errors.ts
@@ -566,15 +566,3 @@ export class IncompatiblePostCssConfigError extends StorybookError {
     });
   }
 }
-
-export class SavingGlobalSettingsFileError extends StorybookError {
-  constructor(public data: { filePath: string; error: Error | unknown }) {
-    super({
-      category: Category.CORE_SERVER,
-      code: 1,
-      message: dedent`
-        Unable to save global settings file to ${data.filePath}
-        ${data.error && `Reason: ${data.error}`}`,
-    });
-  }
-}
diff --git a/code/core/src/telemetry/storybook-metadata.ts b/code/core/src/telemetry/storybook-metadata.ts
@@ -4,6 +4,7 @@ import {
   getProjectRoot,
   getStorybookConfiguration,
   getStorybookInfo,
+  isCI,
   loadMainConfig,
   versions,
 } from 'storybook/internal/common';
@@ -57,10 +58,10 @@ export const computeStorybookMetadata = async ({
   mainConfig?: StorybookConfig & Record<string, any>;
   configDir: string;
 }): Promise<StorybookMetadata> => {
-  const settings = await globalSettings();
+  const settings = isCI ? undefined : await globalSettings();
   const metadata: Partial<StorybookMetadata> = {
     generatedAt: new Date().getTime(),
-    userSince: settings.value.userSince,
+    userSince: settings?.value.userSince,
     hasCustomBabel: false,
     hasCustomWebpack: false,
     hasStaticDirs: false,

diff --git a/code/core/src/telemetry/telemetry.ts b/code/core/src/telemetry/telemetry.ts
@@ -1,6 +1,8 @@
 /// <reference types="node" />
 import * as os from 'node:os';
 
+import { isCI } from 'storybook/internal/common';
+
 import retry from 'fetch-retry';
 import { nanoid } from 'nanoid';
 
@@ -45,7 +47,7 @@ const getOperatingSystem = (): 'Windows' | 'macOS' | 'Linux' | `Other: ${string}
 // by the app. currently:
 // - cliVersion
 const globalContext = {
-  inCI: Boolean(process.env.CI),
+  inCI: isCI,
   isTTY: process.stdout.isTTY,
   platform: getOperatingSystem(),
   nodeVersion: process.versions.node,