packages/cli: update jest config to point to src and use sucrase

packages/cli/config/jest.js

@@ -14,44 +14,67 @@
  * limitations under the License.
  */
 
-const fs = require('fs');
+const fs = require('fs-extra');
 const path = require('path');
 
-// If the package has it's own jest config, we use that instead. It will have to
-// manually extend @spotify/web-scripts/config/jest.config.js that is desired
-if (fs.existsSync('jest.config.js')) {
-  module.exports = require(path.resolve('jest.config.js'));
-} else if (fs.existsSync('jest.config.ts')) {
-  module.exports = require(path.resolve('jest.config.ts'));
-} else {
-  const extraOptions = {
-    modulePaths: ['<rootDir>'],
-    moduleNameMapper: {
-      '\\.(css|less|scss|sss|styl)$': require.resolve('jest-css-modules'),
-    },
+async function getConfig() {
+  // If the package has it's own jest config, we use that instead.
+  if (await fs.pathExists('jest.config.js')) {
+    return require(path.resolve('jest.config.js'));
+  } else if (await fs.pathExists('jest.config.ts')) {
+    return require(path.resolve('jest.config.ts'));
+  }
+
+  const moduleNameMapper = {
+    '\\.(css|less|scss|sss|styl)$': require.resolve('jest-css-modules'),
+  };
+
+  // Only point to src/ if we're not in CI, there we just build packages first anyway
+  if (!process.env.CI) {
+    const LernaProject = require('@lerna/project');
+    const project = new LernaProject(path.resolve('.'));
+    const packages = await project.getPackages();
+
+    // To avoid having to build all deps inside the monorepo before running tests,
+    // we point directory to src/ where applicable.
+    for (const pkg of packages) {
+      const mainSrc = pkg.get('main:src');
+      if (mainSrc) {
+        moduleNameMapper[pkg.name] = path.resolve(pkg.location, mainSrc);
+      }
+    }
+  }
+
+  const options = {
+    rootDir: path.resolve('src'),
+    coverageDirectory: path.resolve('coverage'),
+    collectCoverageFrom: ['**/*.{js,jsx,ts,tsx}', '!**/*.d.ts'],
+    moduleNameMapper,
+
     // We build .esm.js files with plugin:build, so to be able to load these in tests they need to be transformed
     // TODO: jest is working on module support, it's possible that we can remove this in the future
     transform: {
       '\\.esm\\.js$': require.resolve('jest-esm-transformer'),
+      '\\.(js|jsx|ts|tsx)': require.resolve('@sucrase/jest-plugin'),
     },
-    // Default behaviour is to not apply transforms for node_modules, but we still want to tranform .esm.js files
+
+    // Default behaviour is to not apply transforms for node_modules, but we still want
+    // to apply the esm-transformer to .esm.js files, since that's what we use in backstage packages.
     transformIgnorePatterns: ['/node_modules/(?!.*\\.esm\\.js$)'],
   };
 
   // Use src/setupTests.ts as the default location for configuring test env
   if (fs.existsSync('src/setupTests.ts')) {
-    extraOptions.setupFilesAfterEnv = ['<rootDir>/setupTests.ts'];
+    options.setupFilesAfterEnv = ['<rootDir>/setupTests.ts'];
   }
 
-  module.exports = {
-    // We base the jest config on web-scripts, it's pretty flat so we skip any complex merging of config objects
-    // Config can be found here: https://github.com/spotify/web-scripts/blob/master/packages/web-scripts/config/jest.config.js
-    ...require('@spotify/web-scripts/config/jest.config.js'),
-
-    ...extraOptions,
+  return {
+    ...options,
 
     // If the package has a jest object in package.json we merge that config in. This is the recommended
     // location for configuring tests.
     ...require(path.resolve('package.json')).jest,
   };
 }
+
+module.exports = getConfig();