Add tests for Transformer

jestjs · Apr 16, 2018 · 6d208ee · 6d208ee
1 parent f0926d6
commit 6d208ee
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Showing 2 changed files with 55 additions and 8 deletions.
diff --git a/packages/jest-runtime/src/__tests__/script_transformer.test.js b/packages/jest-runtime/src/__tests__/script_transformer.test.js
@@ -85,6 +85,34 @@ jest.mock(
   {virtual: true},
 );
 
+jest.mock(
+  'skipped-required-props-preprocessor',
+  () => {
+    return {};
+  },
+  {virtual: true},
+);
+
+jest.mock(
+  'skipped-required-props-preprocessor',
+  () => {
+    return {};
+  },
+  {virtual: true},
+);
+
+jest.mock(
+  'skipped-required-create-transformer-props-preprocessor',
+  () => {
+    return {
+      createTransformer() {
+        return {};
+      },
+    };
+  },
+  {virtual: true},
+);
+
 const getCachePath = (fs, config) => {
   for (const path in mockFs) {
     if (path.startsWith(config.cacheDirectory)) {
@@ -262,6 +290,28 @@ describe('ScriptTransformer', () => {
     },
   );
 
+  it("throws an error if `process` doesn't defined", () => {
+    Object.assign(config, {
+      transform: [['^.+\\.js$', 'skipped-required-props-preprocessor']],
+    });
+    const scriptTransformer = new ScriptTransformer(config);
+    expect(() =>
+      scriptTransformer.transformSource('sample.js', '', false),
+    ).toThrow('Jest: a transform must export a `process` function.');
+  });
+
+  it('throws an error if createTransformer returns object without `process` method', () => {
+    Object.assign(config, {
+      transform: [
+        ['^.+\\.js$', 'skipped-required-create-transformer-props-preprocessor'],
+      ],
+    });
+    const scriptTransformer = new ScriptTransformer(config);
+    expect(() =>
+      scriptTransformer.transformSource('sample.js', '', false),
+    ).toThrow('Jest: a transform must export a `process` function.');
+  });
+
   it('uses the supplied preprocessor', () => {
     config = Object.assign(config, {
       transform: [['^.+\\.js$', 'test_preprocessor']],

diff --git a/packages/jest-runtime/src/script_transformer.js b/packages/jest-runtime/src/script_transformer.js
@@ -136,17 +136,14 @@ export default class ScriptTransformer {
 
       // $FlowFixMe
       transform = (require(transformPath): Transformer);
-      if (
-        typeof transform.process !== 'function' &&
-        typeof transform.createTransformer !== 'function'
-      ) {
-        throw new TypeError(
-          'Jest: a transform must export a `process` or `createTransformer` function.',
-        );
-      }
       if (typeof transform.createTransformer === 'function') {
         transform = transform.createTransformer();
       }
+      if (typeof transform.process !== 'function') {
+        throw new TypeError(
+          'Jest: a transform must export a `process` function.',
+        );
+      }
       this._transformCache.set(transformPath, transform);
     }
     return transform;