feat(jest-transform): add additionalTransformer

uhyo · Feb 18, 2024 · e320624 · e320624
1 parent 9b4d246
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diff --git a/packages/jest-transform/README.md b/packages/jest-transform/README.md
@@ -18,23 +18,21 @@ Example Jest configuration:
 
 `@nitrogql/jest-transform` is only capable of emitting ES modules. If you are running CommonJS modules during your tests, you will need to use another transformer (for example, `babel-jest` or `ts-jest`) to further transform the output from ES modules to CommonJS.
 
-Using multiple transformers should be possible by using the [jest-chain-transform](https://www.npmjs.com/package/jest-chain-transform) package:
+`@nitrogql/jest-transform` lets you apply another transformer to the output. To do so, use the `additionalTransformer` and `additionalTransformerFilenameSuffix` option:
 
 ```js
 {
   "transform": {
     // For example, if you are using ts-jest...
-    "^.+\.tsx?": "ts-jest",
-    // Then, use jest-chain-transform to chain @nitrogql/jest-transform
-    // with ts-jest
-    "^.+\\.graphql$": ["jest-chain-transform", {
-      "transformers": [
-        ["@nitrogql/jest-transform", {
-          "configFile":  path.resolve(__dirname, "nitrogql.config.js")
-        }],
-        "ts-jest"
-      ]
+    "^.+\.tsx?": ["ts-jest", { isolatedModules: true }],
+    "^.+\\.graphql$": ["@nitrogql/jest-transform", {
+      "configFile":  path.resolve(__dirname, "nitrogql.config.yml"),
+      // Then, use the additionalTransformer option to apply ts-jest to the output.
+      "additionalTransformer": ["ts-jest", { isolatedModules: true }],
+      // ts-jest expects .ts files, so we need to change the file extension
+      // by applying the additionalTransformerFilenameSuffix option.
+      "additionalTransformerFilenameSuffix": ".ts"
     }]
-  }
+  },
 }
 ```
diff --git a/packages/jest-transform/src/index.ts b/packages/jest-transform/src/index.ts
@@ -1,57 +1,118 @@
 import { readFileSync } from "node:fs";
-import type { SyncTransformer, TransformedSource } from "@jest/transform";
+import type {
+  SyncTransformer,
+  TransformedSource,
+  TransformerCreator,
+} from "@jest/transform";
 import { executeConfigFileSync } from "@nitrogql/core";
 import { init } from "@nitrogql/loader-core";
 
-const { initiateTask, getLog } = await init();
-
-let lastLoadedConfigPath: string | undefined = undefined;
-
 export type TransformerConfig = {
   /**
    * The path to the nitrogql config file.
    */
   configFile?: string;
+  /**
+   * Additional transformer to apply to the generated source code.
+   */
+  additionalTransformer?:
+    | string
+    | [transformer: string, transformerConfig: unknown];
+  /**
+   * Suffix to add to filename when passing code to the additional transformer.
+   * @default ".js"
+   */
+  additionalTransformerFilenameSuffix?: string;
 };
 
-const transformer: SyncTransformer<TransformerConfig> = {
-  process(sourceText, sourcePath, options): TransformedSource {
-    const configFile = options.transformerConfig.configFile;
-    const task = initiateTask(sourcePath, sourceText);
-
-    if (lastLoadedConfigPath !== configFile && configFile) {
-      const configFileSource = configFileIsJS(configFile)
-        ? executeConfigFileSync(configFile)
-        : readFileSync(configFile, "utf-8");
-      task.loadConfig(configFileSource);
-    }
-    lastLoadedConfigPath = configFile;
-
-    while (true) {
-      const status = task.status();
-      switch (status.status) {
-        case "fileRequired": {
-          const requiredFiles = status.files;
-          for (const requiredFile of requiredFiles) {
-            const requiredFileSource = readFileSync(requiredFile, "utf-8");
-            task.supplyFile(requiredFile, requiredFileSource);
+const createTransformer: TransformerCreator<
+  SyncTransformer<TransformerConfig>,
+  TransformerConfig
+> = async (options) => {
+  const { initiateTask } = await init();
+
+  let lastLoadedConfigPath: string | undefined = undefined;
+
+  const additionalTransformer = options?.additionalTransformer
+    ? await loadTransformer(options.additionalTransformer)
+    : undefined;
+
+  const transformer: SyncTransformer<TransformerConfig> = {
+    process(sourceText, sourcePath, options): TransformedSource {
+      const configFile = options.transformerConfig.configFile;
+      const task = initiateTask(sourcePath, sourceText);
+
+      if (lastLoadedConfigPath !== configFile && configFile) {
+        const configFileSource = configFileIsJS(configFile)
+          ? executeConfigFileSync(configFile)
+          : readFileSync(configFile, "utf-8");
+        task.loadConfig(configFileSource);
+      }
+      lastLoadedConfigPath = configFile;
+
+      let result: string;
+      loop: while (true) {
+        const status = task.status();
+        switch (status.status) {
+          case "fileRequired": {
+            const requiredFiles = status.files;
+            for (const requiredFile of requiredFiles) {
+              const requiredFileSource = readFileSync(requiredFile, "utf-8");
+              task.supplyFile(requiredFile, requiredFileSource);
+            }
+            break;
+          }
+          case "ready": {
+            result = task.emit();
+            task.free();
+            break loop;
           }
-          break;
-        }
-        case "ready": {
-          const result = task.emit();
-          task.free();
-          return {
-            code: result,
-          };
         }
       }
-    }
-  },
+      if (additionalTransformer === undefined) {
+        return { code: result };
+      }
+      const transformed = additionalTransformer[0].process(
+        result,
+        sourcePath +
+          (options.transformerConfig.additionalTransformerFilenameSuffix ??
+            ".js"),
+        {
+          ...options,
+          transformerConfig: additionalTransformer[1],
+        }
+      );
+      return transformed;
+    },
+  };
+  return transformer;
 };
 
-export default transformer;
+export default {
+  createTransformer,
+};
 
 function configFileIsJS(configFile: string) {
   return /\.[cm]?[jt]s$/.test(configFile);
 }
+
+async function loadTransformer(
+  transformer: string | [transformer: string, transformerConfig: unknown]
+): Promise<[transformer: SyncTransformer<unknown>, config: unknown]> {
+  let transformerModule, transformerConfig: unknown;
+  if (typeof transformer === "string") {
+    transformerModule = await import(transformer);
+  } else {
+    transformerModule = await import(transformer[0]);
+    transformerConfig = transformer[1];
+  }
+  while (transformerModule.default) {
+    transformerModule = transformerModule.default;
+  }
+  if (transformerModule.createTransformer) {
+    transformerModule = await transformerModule.createTransformer(
+      transformerConfig
+    );
+  }
+  return [transformerModule, transformerConfig];
+}