Enable strict mode

.github/workflows/typecheck.yml

@@ -0,0 +1,19 @@
+on: [push, pull_request]
+
+jobs:
+    typecheck:
+        runs-on: ubuntu-latest
+        steps:
+        - uses: actions/checkout@v2
+
+        - name: Use Node.js 18.x
+          uses: actions/setup-node@v1
+          with:
+            node-version: '18.x'
+
+        - name: Install dependencies
+          uses: bahmutov/npm-install@v1
+
+        - name: Type check
+          run: yarn tsc
+

src/config/jest-playwright.ts

@@ -85,7 +85,7 @@ export const getJestConfig = () => {
     snapshotSerializers: [jestSerializerHtmlPath],
     testEnvironmentOptions: {
       'jest-playwright': {
-        browsers: TEST_BROWSERS.split(',')
+        browsers: TEST_BROWSERS?.split(',')
           .map((p) => p.trim().toLowerCase())
           .filter(Boolean),
         collectCoverage: STORYBOOK_COLLECT_COVERAGE === 'true',

src/csf/transformCsf.ts

@@ -37,9 +37,20 @@ const prefixFunction = (
     id: t.stringLiteral(toId(title, name)),
   };
 
-  const result = makeArray(testPrefixer(context));
-  const stmt = result[1] as t.ExpressionStatement;
-  return stmt.expression;
+  let result = input;
+  if (testPrefixer) {
+    const prefixResult = makeArray(testPrefixer(context));
+    const stmt = prefixResult[1] as t.ExpressionStatement;
+    if (stmt) {
+      result = stmt.expression;
+    }
+  }
+
+  if (!result) {
+    result = t.nullLiteral();
+  }
+
+  return result;
 };
 
 const makePlayTest = (
@@ -91,11 +102,11 @@ export const transformCsf = (
     makeTitle,
   }: TransformOptions = {}
 ) => {
-  const csf = loadCsf(code, { makeTitle });
+  const csf = loadCsf(code, { makeTitle: makeTitle || ((userTitle: string) => userTitle) });
   csf.parse();
 
   const storyExports = Object.keys(csf._stories);
-  const title = csf.meta.title;
+  const title = csf.meta?.title;
 
   const storyPlays = storyExports.reduce((acc, key) => {
     const annotations = csf._storyAnnotations[key];
@@ -107,14 +118,16 @@ export const transformCsf = (
   const playTests = storyExports
     .map((key: string) => {
       let tests: t.Statement[] = [];
-      tests = [...tests, ...makePlayTest(key, title, storyPlays[key], testPrefixer)];
+      if (title) {
+        tests = [...tests, ...makePlayTest(key, title, storyPlays[key], testPrefixer)];
+      }
 
       if (tests.length) {
         return makeDescribe(key, tests);
       }
       return null;
     })
-    .filter(Boolean);
+    .filter(Boolean) as babel.types.Statement[];
 
   const allTests = playTests;
 
@@ -123,7 +136,7 @@ export const transformCsf = (
   if (!clearBody) result = `${result}${code}\n`;
   if (allTests.length) {
     const describe = makeDescribe(
-      csf.meta.title,
+      csf.meta?.title as string,
       allTests,
       beforeEachPrefixer ? makeBeforeEach(beforeEachPrefixer) : undefined
     ) as babel.types.Node;
@@ -135,7 +148,7 @@ export const transformCsf = (
       }
     `;
   } else if (insertTestIfEmpty) {
-    result = `describe('${csf.meta.title}', () => { it('no-op', () => {}) });`;
+    result = `describe('${csf.meta?.title}', () => { it('no-op', () => {}) });`;
   }
   return result;
 };

src/playwright/transformPlaywright.ts

@@ -71,7 +71,8 @@ const makeTitleFactory = (filename: string) => {
   const { workingDir, normalizedStoriesEntries } = getStorybookMetadata();
   const filePath = './' + relative(workingDir, filename);
 
-  return (userTitle: string) => userOrAutoTitle(filePath, normalizedStoriesEntries, userTitle);
+  return (userTitle: string) =>
+    userOrAutoTitle(filePath, normalizedStoriesEntries, userTitle) as string;
 };
 
 export const transformPlaywright = (src: string, filename: string) => {

src/setup-page.ts

@@ -1,5 +1,5 @@
 import type { Page, BrowserContext } from 'playwright';
-import readPackageUp from 'read-pkg-up';
+import readPackageUp, { NormalizedReadResult } from 'read-pkg-up';
 import { PrepareContext } from './playwright/hooks';
 import { getTestRunnerConfig } from './util';
 
@@ -55,7 +55,7 @@ export const setupPage = async (page: Page, browserContext: BrowserContext) => {
 
   const viewMode = process.env.VIEW_MODE || 'story';
   const renderedEvent = viewMode === 'docs' ? 'docsRendered' : 'storyRendered';
-  const { packageJson } = await readPackageUp();
+  const { packageJson } = (await readPackageUp()) as NormalizedReadResult;
   const { version: testRunnerVersion } = packageJson;
 
   const referenceURL = process.env.REFERENCE_URL && sanitizeURL(process.env.REFERENCE_URL);
@@ -73,7 +73,7 @@ export const setupPage = async (page: Page, browserContext: BrowserContext) => {
   if (testRunnerConfig?.prepare) {
     await testRunnerConfig.prepare({ page, browserContext, testRunnerConfig });
   } else {
-    await defaultPrepare({ page, browserContext, testRunnerConfig });
+    if (testRunnerConfig) await defaultPrepare({ page, browserContext, testRunnerConfig });
   }
 
   // if we ever want to log something from the browser to node

src/test-storybook.ts

@@ -35,7 +35,7 @@ process.on('unhandledRejection', (err) => {
 });
 
 const log = (message: string) => console.log(`[test-storybook] ${message}`);
-const error = (err: { message: any; stack: any }) => {
+const error = (err: Error) => {
   if (err instanceof Error) {
     console.error(`\x1b[31m[test-storybook]\x1b[0m ${err.message} \n\n${err.stack}`);
   } else {
@@ -250,7 +250,10 @@ async function getIndexTempDir(url: string) {
       fs.writeFileSync(tmpFile, test as string);
     });
   } catch (err) {
-    error(err);
+    const errorMessage = err instanceof Error ? err.message : String(err);
+    const errorObject = new Error(errorMessage);
+    errorObject.stack = err instanceof Error ? err.stack : undefined;
+    error(errorObject);
     process.exit(1);
   }
   return tmpDir;

src/util/getCliOptions.ts

@@ -48,16 +48,20 @@ export const getCliOptions = (): CliOptions => {
     jestOptions: process.argv.splice(0, 2),
   };
 
-  const finalOptions = Object.keys(allOptions).reduce((acc, key: StorybookRunnerCommand) => {
-    if (STORYBOOK_RUNNER_COMMANDS.includes(key)) {
-      copyOption(acc.runnerOptions, key, allOptions[key]);
+  const finalOptions = Object.keys(allOptions).reduce((acc: CliOptions, key: string) => {
+    if (STORYBOOK_RUNNER_COMMANDS.includes(key as StorybookRunnerCommand)) {
+      copyOption(
+        acc.runnerOptions,
+        key as StorybookRunnerCommand,
+        allOptions[key as StorybookRunnerCommand]
+      );
     } else {
-      if (allOptions[key] === true) {
+      if (allOptions[key as StorybookRunnerCommand] === true) {
         acc.jestOptions.push(`--${key}`);
-      } else if (allOptions[key] === false) {
+      } else if (allOptions[key as StorybookRunnerCommand] === false) {
         acc.jestOptions.push(`--no-${key}`);
       } else {
-        acc.jestOptions.push(`--${key}`, allOptions[key] as string);
+        acc.jestOptions.push(`--${key}="${allOptions[key as StorybookRunnerCommand]}"`);
       }
     }
 

src/util/getParsedCliOptions.ts

@@ -1,5 +1,5 @@
 import type { CliOptions } from './getCliOptions';
-import { program } from 'commander';
+import { CommanderError, program } from 'commander';
 
 type ParsedCliOptions = {
   options: CliOptions['runnerOptions'];
@@ -82,23 +82,27 @@ export const getParsedCliOptions = (): ParsedCliOptions => {
 
   try {
     program.parse();
-  } catch (err) {
-    switch (err.code) {
-      case 'commander.unknownOption': {
-        program.outputHelp();
-        console.warn(
-          `\nIf you'd like this option to be supported, please open an issue at https://github.com/storybookjs/test-runner/issues/new\n`
-        );
-        process.exit(1);
-      }
+  } catch (err: unknown) {
+    if (err instanceof CommanderError) {
+      switch (err.code) {
+        case 'commander.unknownOption': {
+          program.outputHelp();
+          console.warn(
+            `\nIf you'd like this option to be supported, please open an issue at https://github.com/storybookjs/test-runner/issues/new\n`
+          );
+          process.exit(1);
+        }
 
-      case 'commander.helpDisplayed': {
-        process.exit(0);
-      }
+        case 'commander.helpDisplayed': {
+          process.exit(0);
+        }
 
-      default: {
-        throw err;
+        default: {
+          throw err;
+        }
       }
+    } else {
+      throw err;
     }
   }
 

src/util/getStorybookMetadata.ts

@@ -1,13 +1,14 @@
 import { join } from 'path';
 import { normalizeStories, getProjectRoot } from '@storybook/core-common';
 import { getStorybookMain } from './getStorybookMain';
+import { StoriesEntry } from '@storybook/types';
 
 export const getStorybookMetadata = () => {
   const workingDir = getProjectRoot();
-  const configDir = process.env.STORYBOOK_CONFIG_DIR;
+  const configDir = process.env.STORYBOOK_CONFIG_DIR || '';
 
   const main = getStorybookMain(configDir);
-  const normalizedStoriesEntries = normalizeStories(main.stories, {
+  const normalizedStoriesEntries = normalizeStories(main?.stories as StoriesEntry[], {
     configDir,
     workingDir,
   }).map((specifier) => ({

src/util/getTestRunnerConfig.ts

@@ -6,7 +6,7 @@ let testRunnerConfig: TestRunnerConfig;
 let loaded = false;
 
 export const getTestRunnerConfig = (
-  configDir: string = process.env.STORYBOOK_CONFIG_DIR
+  configDir = process.env.STORYBOOK_CONFIG_DIR || ''
 ): TestRunnerConfig | undefined => {
   // testRunnerConfig can be undefined
   if (loaded) {

tsconfig.json

@@ -15,7 +15,9 @@
     "skipLibCheck": true,
     "target": "es2020",
     "types": ["jest", "node"],
-    "moduleResolution": "node"
+    "moduleResolution": "node",
+    "strict": true,
+    "noEmit": true,
   },
   "include": ["src/**/*.ts"],
   "exclude": ["src/**/*.test.ts"]