Rehydrate UncommitedAsset in Transformation#readFromCache (#5570)

packages/core/core/src/Transformation.js

@@ -1,6 +1,7 @@
 // @flow strict-local
 
 import type {
+  AST,
   FilePath,
   GenerateOutput,
   Transformer,
@@ -397,12 +398,28 @@ export default class Transformation {
       return null;
     }
 
-    return cachedAssets.map(
-      (value: AssetValue) =>
-        new UncommittedAsset({
+    return Promise.all(
+      cachedAssets.map(async (value: AssetValue) => {
+        let content =
+          value.contentKey != null
+            ? this.options.cache.getStream(value.contentKey)
+            : null;
+        let mapBuffer =
+          value.astKey != null
+            ? await this.options.cache.getBlob<Buffer>(value.astKey)
+            : null;
+        let ast =
+          value.astKey != null
+            ? await this.options.cache.getBlob<AST>(value.astKey)
+            : null;
+        return new UncommittedAsset({
           value,
           options: this.options,
-        }),
+          content,
+          mapBuffer,
+          ast,
+        });
+      }),
     );
   }
 

packages/core/core/src/UncommittedAsset.js

@@ -18,6 +18,7 @@ import type {
 } from './types';
 
 import v8 from 'v8';
+import invariant from 'assert';
 import {Readable} from 'stream';
 import SourceMap from '@parcel/source-map';
 import {
@@ -179,7 +180,7 @@ export default class UncommittedAsset {
       return (await this.content).toString();
     }
 
-    return '';
+    invariant(false, 'Internal error: missing content');
   }
 
   async getBuffer(): Promise<Buffer> {

packages/core/integration-tests/test/cache.js

@@ -17,7 +17,7 @@ let inputDir: string;
 
 function runBundle(entries = 'src/index.js', opts) {
   entries = (Array.isArray(entries) ? entries : [entries]).map(entry =>
-    path.join(inputDir, entry),
+    path.resolve(inputDir, entry),
   );
 
   return bundler(entries, {
@@ -2636,4 +2636,96 @@ describe('cache', function() {
       assert.equal(bundles.length, 4);
     });
   });
+
+  it('should correctly read additional child assets from cache', async function() {
+    await ncp(
+      path.join(__dirname, '/integration/postcss-modules-cjs'),
+      path.join(inputDir),
+    );
+
+    let entries = 'index.js';
+
+    let b = await runBundle(entries, {minify: false});
+    let result1 = (await run(b.bundleGraph))();
+
+    b = await runBundle(entries, {minify: true});
+    let result2 = (await run(b.bundleGraph))();
+
+    b = await runBundle(entries, {minify: false});
+    let result3 = (await run(b.bundleGraph))();
+
+    assert(typeof result1 === 'string' && result1.includes('foo'));
+    assert.strictEqual(result1, result2);
+    assert.strictEqual(result1, result3);
+  });
+
+  it('should correctly read additional child assets from cache 2', async function() {
+    await ncp(
+      path.join(__dirname, '/integration/postcss-modules-cjs'),
+      path.join(inputDir),
+    );
+
+    let entries = 'index.js';
+
+    await overlayFS.writeFile(
+      path.join(inputDir, 'foo.module.css'),
+      `.foo {
+  color: red;
+}`,
+    );
+
+    let b = await runBundle(entries);
+    let result1 = (await run(b.bundleGraph))();
+
+    await overlayFS.writeFile(
+      path.join(inputDir, 'foo.module.css'),
+      `.foo {
+  color: blue;
+}`,
+    );
+
+    b = await runBundle(entries);
+    let result2 = (await run(b.bundleGraph))();
+
+    await overlayFS.writeFile(
+      path.join(inputDir, 'foo.module.css'),
+      `.foo {
+  color: red;
+}`,
+    );
+
+    b = await runBundle(entries);
+    let result3 = (await run(b.bundleGraph))();
+
+    assert(typeof result1 === 'string' && result1.includes('foo'));
+    assert.strictEqual(result1, result2);
+    assert.strictEqual(result1, result3);
+  });
+
+  it('should correctly reuse intermediate pipeline results when transforming', async function() {
+    await ncp(path.join(__dirname, '/integration/json'), path.join(inputDir));
+
+    let entry = path.join(inputDir, 'index.js');
+    let original = await overlayFS.readFile(entry, 'utf8');
+
+    let b = await runBundle(entry);
+    let result1 = (await run(b.bundleGraph))();
+
+    await overlayFS.writeFile(
+      entry,
+      'module.exports = function(){ return 10; }',
+    );
+
+    b = await runBundle(entry);
+    let result2 = (await run(b.bundleGraph))();
+
+    await overlayFS.writeFile(entry, original);
+
+    b = await runBundle(entry);
+    let result3 = (await run(b.bundleGraph))();
+
+    assert.strictEqual(result1, 3);
+    assert.strictEqual(result2, 10);
+    assert.strictEqual(result3, 3);
+  });
 });