Remove 'createTransformer' from Transformer types

closes jestjs#12403
fatso83 · Feb 16, 2022 · 47062c7 · 47062c7
1 parent 199f981
commit 47062c7
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Showing 2 changed files with 17 additions and 6 deletions.
diff --git a/packages/jest-transform/src/ScriptTransformer.ts b/packages/jest-transform/src/ScriptTransformer.ts
@@ -42,6 +42,7 @@ import type {
   TransformResult,
   TransformedSource,
   Transformer,
+  TransformerFactory,
 } from './types';
 // Use `require` to avoid TS rootDir
 const {version: VERSION} = require('../package.json');
@@ -72,6 +73,13 @@ async function waitForPromiseWithCleanup(
   }
 }
 
+// type predicate
+function isTransformerFactory(
+  t: Transformer | TransformerFactory,
+): t is TransformerFactory {
+  return typeof (t as TransformerFactory).createTransformer === 'function';
+}
+
 class ScriptTransformer {
   private readonly _cache: ProjectCache;
   private readonly _transformCache = new Map<
@@ -259,14 +267,13 @@ class ScriptTransformer {
     await Promise.all(
       this._config.transform.map(
         async ([, transformPath, transformerConfig]) => {
-          let transformer: Transformer = await requireOrImportModule(
-            transformPath,
-          );
+          let transformer: Transformer | TransformerFactory =
+            await requireOrImportModule(transformPath);
 
           if (!transformer) {
             throw new Error(makeInvalidTransformerError(transformPath));
           }
-          if (typeof transformer.createTransformer === 'function') {
+          if (isTransformerFactory(transformer)) {
             transformer = transformer.createTransformer(transformerConfig);
           }
           if (

diff --git a/packages/jest-transform/src/types.ts b/packages/jest-transform/src/types.ts
@@ -76,7 +76,6 @@ export interface SyncTransformer<OptionType = unknown> {
    * If V8 coverage is _not_ active, and this is `false`. Jest will instrument the code returned by this transformer using Babel.
    */
   canInstrument?: boolean;
-  createTransformer?: (options?: OptionType) => SyncTransformer<OptionType>;
 
   getCacheKey?: (
     sourceText: string,
@@ -111,7 +110,6 @@ export interface AsyncTransformer<OptionType = unknown> {
    * If V8 coverage is _not_ active, and this is `false`. Jest will instrument the code returned by this transformer using Babel.
    */
   canInstrument?: boolean;
-  createTransformer?: (options?: OptionType) => AsyncTransformer<OptionType>;
 
   getCacheKey?: (
     sourceText: string,
@@ -141,3 +139,9 @@ export interface AsyncTransformer<OptionType = unknown> {
 export type Transformer<OptionType = unknown> =
   | SyncTransformer<OptionType>
   | AsyncTransformer<OptionType>;
+
+type TransformerCreator<OptionType = unknown> = (
+  options?: OptionType,
+) => Transformer<OptionType>;
+
+export type TransformerFactory = {createTransformer: TransformerCreator};