packager: GlobalTransformCache: add unit test

Summary: Finally adding some unit test to increase confidence in the correctness of that piece of code.

Reviewed By: davidaurelio

Differential Revision: D4721543

fbshipit-source-id: 56776290d61f2b51c69d7eeae09663e3bc892b50

packages/metro-bundler/src/lib/__tests__/GlobalTransformCache-test.js

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+jest.disableAutomock();
+jest.useRealTimers();
+
+const fetchMock = jest.fn();
+jest.mock('node-fetch', () => fetchMock);
+
+const GlobalTransformCache = require('../GlobalTransformCache');
+const FetchError = require('node-fetch/lib/fetch-error');
+
+async function fetchResultURIs(keys: Array<string>): Promise<Map<string, string>> {
+  return new Map(keys.map(key => [key, `http://globalcache.com/${key}`]));
+}
+
+async function fetchResultFromURI(uri: string): Promise<?CachedResult> {
+  return {
+    code: `/* code from ${uri} */`,
+    dependencies: [],
+    dependencyOffsets: [],
+  };
+}
+
+describe('GlobalTransformCache', () => {
+
+  it('fetches results', async () => {
+    const cache = new GlobalTransformCache(fetchResultURIs, fetchResultFromURI, null, [
+      {dev: true, minify: false, platform: 'ios'},
+    ]);
+    const transformOptions = {
+      dev: true,
+      minify: false,
+      platform: 'ios',
+      transform: {projectRoots: [__dirname]},
+    };
+    const result = await Promise.all([cache.fetch({
+      filePath: 'foo.js',
+      sourceCode: '/* beep */',
+      getTransformCacheKey: () => 'abcd',
+      transformOptions,
+    }), cache.fetch({
+      filePath: 'bar.js',
+      sourceCode: '/* boop */',
+      getTransformCacheKey: () => 'abcd',
+      transformOptions,
+    })]);
+    expect(result).toMatchSnapshot();
+  });
+
+  describe('fetchResultFromURI', () => {
+
+    const defaultFetchMockImpl = async uri => ({
+      status: 200,
+      json: async () => ({
+        code: `/* code from ${uri} */`,
+        dependencies: [],
+        dependencyOffsets: [],
+      }),
+    });
+
+    beforeEach(() => {
+      fetchMock.mockReset();
+    });
+
+    it('fetches result', async () => {
+      fetchMock.mockImplementation(defaultFetchMockImpl);
+      const result = await GlobalTransformCache.fetchResultFromURI('http://globalcache.com/foo');
+      expect(result).toMatchSnapshot();
+    });
+
+    it('retries once on timeout', async () => {
+      fetchMock.mockImplementation(async uri => {
+        fetchMock.mockImplementation(defaultFetchMockImpl);
+        throw new FetchError('timeout!', 'request-timeout');
+      });
+      const result = await GlobalTransformCache.fetchResultFromURI('http://globalcache.com/foo');
+      expect(result).toMatchSnapshot();
+    });
+
+  });
+
+});

packages/metro-bundler/src/lib/__tests__/__snapshots__/GlobalTransformCache-test.js.snap

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+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`GlobalTransformCache fetchResultFromURI fetches result 1`] = `
+Object {
+  "code": "/* code from http://globalcache.com/foo */",
+  "dependencies": Array [],
+  "dependencyOffsets": Array [],
+}
+`;
+
+exports[`GlobalTransformCache fetchResultFromURI retries once on timeout 1`] = `
+Object {
+  "code": "/* code from http://globalcache.com/foo */",
+  "dependencies": Array [],
+  "dependencyOffsets": Array [],
+}
+`;
+
+exports[`GlobalTransformCache fetches results 1`] = `
+Array [
+  Object {
+    "code": "/* code from http://globalcache.com/2ad175cb80ae79fd33b914bfb392fb6742982d2a-foo.js */",
+    "dependencies": Array [],
+    "dependencyOffsets": Array [],
+  },
+  Object {
+    "code": "/* code from http://globalcache.com/d6c0a1a4199d572ab68b36c07d0d68607eebb131-bar.js */",
+    "dependencies": Array [],
+    "dependencyOffsets": Array [],
+  },
+]
+`;