feat(compare-func): pass cacheData to the compare() function

Also added caching the source file.

Author: pat841

README.md

@@ -52,7 +52,7 @@ module.exports = {
 |    **`cacheKey`**     |    `{Function(options, request) -> {String}}`    |                       `undefined`                       | Allows you to override default cache key generator                                                                                                                     |
 | **`cacheDirectory`**  |                    `{String}`                    | `findCacheDir({ name: 'cache-loader' }) or os.tmpdir()` | Provide a cache directory where cache items should be stored (used for default read/write implementation)                                                              |
 | **`cacheIdentifier`** |                    `{String}`                    |     `cache-loader:{version} {process.env.NODE_ENV}`     | Provide an invalidation identifier which is used to generate the hashes. You can use it for extra dependencies of loaders (used for default read/write implementation) |
-|     **`compare`**     |      `{Function(stats, dep) -> {Boolean}}`       |                       `undefined`                       | Allows you to override default comparison function between the cached dependency and the one is being read. Return `true` to use the cached resource                   |
+|     **`compare`**     | `{Function(stats, dep, cacheData) -> {Boolean}}` |                       `undefined`                       | Allows you to override default comparison function between the cached dependency and the one is being read. Return `true` to use the cached resource                   |
 |    **`precision`**    |                    `{Number}`                    |                           `0`                           | Round `mtime` by this number of milliseconds both for `stats` and `dep` before passing those params to the comparing function                                          |
 |      **`read`**       |    `{Function(cacheKey, callback) -> {void}}`    |                       `undefined`                       | Allows you to override default read cache data from file                                                                                                               |
 |    **`readOnly`**     |                   `{Boolean}`                    |                         `false`                         | Allows you to override default value and make the cache read only (useful for some environments where you don't want the cache to be updated, only read from it)       |

src/index.js

@@ -57,7 +57,7 @@ function roundMs(mtime, precision) {
 // right before writing. Every other internal steps with the paths
 // should be accomplish over absolute paths. Otherwise we have the risk
 // to break watchpack -> chokidar watch logic  over webpack@4 --watch
-function loader(...args) {
+function loader(source, ...args) {
   const options = Object.assign({}, defaults, getOptions(this));
 
   validateOptions(schema, options, {
@@ -70,7 +70,7 @@ function loader(...args) {
   // In case we are under a readOnly mode on cache-loader
   // we don't want to write or update any cache file
   if (readOnly) {
-    this.callback(null, ...args);
+    this.callback(null, source, ...args);
     return;
   }
 
@@ -117,11 +117,11 @@ function loader(...args) {
     ],
     (err, taskResults) => {
       if (err) {
-        callback(null, ...args);
+        callback(null, source, ...args);
         return;
       }
       if (!cache) {
-        callback(null, ...args);
+        callback(null, source, ...args);
         return;
       }
       const [deps, contextDeps] = taskResults;
@@ -132,13 +132,14 @@ function loader(...args) {
             options.cacheContext,
             data.remainingRequest
           ),
+          source,
           dependencies: deps,
           contextDependencies: contextDeps,
-          result: args,
+          result: [source, ...args],
         },
         () => {
           // ignore errors here
-          callback(null, ...args);
+          callback(null, source, ...args);
         }
       );
     }
@@ -228,7 +229,7 @@ function pitch(remainingRequest, prevRequest, dataInput) {
 
           // If the compare function returns false
           // we not read from cache
-          if (compareFn(compStats, compDep) !== true) {
+          if (compareFn(compStats, compDep, cacheData) !== true) {
             eachCallback(true);
             return;
           }

test/__snapshots__/cacheContext-option.test.js.snap

@@ -10,6 +10,10 @@ exports[`cacheContext option should generate relative paths to the project root:
 "[
   {
     \\"remainingRequest\\": \\"test/fixtures/basic/file_1.js\\",
+    \\"source\\": {
+      \\"type\\": \\"Buffer\\",
+      \\"data\\": \\"base64:LyogZXNsaW50LWRpc2FibGUgKi8KY29uc29sZS5sb2coJ2ZpbGVfMScpOwo=\\"
+    },
     \\"dependencies\\": [
       {
         \\"path\\": \\"test/fixtures/basic/file_1.js\\",
@@ -30,6 +34,10 @@ exports[`cacheContext option should generate relative paths to the project root:
   },
   {
     \\"remainingRequest\\": \\"test/fixtures/basic/file_2.js\\",
+    \\"source\\": {
+      \\"type\\": \\"Buffer\\",
+      \\"data\\": \\"base64:LyogZXNsaW50LWRpc2FibGUgKi8KY29uc29sZS5sb2coJ2ZpbGVfMicpOwo=\\"
+    },
     \\"dependencies\\": [
       {
         \\"path\\": \\"test/fixtures/basic/file_2.js\\",
@@ -50,6 +58,10 @@ exports[`cacheContext option should generate relative paths to the project root:
   },
   {
     \\"remainingRequest\\": \\"test/fixtures/basic/index.js\\",
+    \\"source\\": {
+      \\"type\\": \\"Buffer\\",
+      \\"data\\": \\"base64:LyogZXNsaW50LWRpc2FibGUgKi8KcmVxdWlyZSgnLi9maWxlXzEuanMnKTsKcmVxdWlyZSgnLi9maWxlXzIuanMnKTsKCmNvbnNvbGUubG9nKCdiYXNpY19lbnRyeScpOwo=\\"
+    },
     \\"dependencies\\": [
       {
         \\"path\\": \\"test/fixtures/basic/index.js\\",

test/compare-option.test.js

@@ -12,8 +12,8 @@ const mockWebpackConfig = {
   loader: {
     options: {
       cacheDirectory: mockRandomTmpDir,
-      compare: (stats, dep) => {
-        mockCacheLoaderCompareFn(stats, dep);
+      compare: (stats, dep, cacheData) => {
+        mockCacheLoaderCompareFn(stats, dep, cacheData);
         return true;
       },
     },
@@ -26,8 +26,8 @@ const mockRelativeWebpackConfig = {
     options: {
       cacheContext: path.resolve('./'),
       cacheDirectory: mockRandomTmpDir,
-      compare: (stats, dep) => {
-        mockCacheLoaderCompareOnRelativeFn(stats, dep);
+      compare: (stats, dep, cacheData) => {
+        mockCacheLoaderCompareOnRelativeFn(stats, dep, cacheData);
         return true;
       },
     },
@@ -50,12 +50,12 @@ describe('compare option', () => {
     expect(mockCacheLoaderCompareFn).toHaveBeenCalled();
   });
 
-  it('should call compare function with 2 args', async () => {
+  it('should call compare function with 3 args', async () => {
     const testId = './basic/index.js';
     await webpack(testId, mockWebpackConfig);
     await webpack(testId, mockWebpackConfig);
     expect(mockCacheLoaderCompareFn).toHaveBeenCalled();
-    expect(mockCacheLoaderCompareFn.mock.calls[0].length).toBe(2);
+    expect(mockCacheLoaderCompareFn.mock.calls[0].length).toBe(3);
   });
 
   it('should call compare function with correct args', async () => {
@@ -68,11 +68,19 @@ describe('compare option', () => {
     const stats = mockCacheLoaderCompareFn.mock.calls[0][0];
     // eslint-disable-next-line
     const dep = mockCacheLoaderCompareFn.mock.calls[0][1];
+    // eslint-disable-next-line
+    const cacheData = mockCacheLoaderCompareFn.mock.calls[0][2];
     expect(stats).toBeDefined();
     expect(stats instanceof fs.Stats);
     expect(dep).toBeDefined();
     expect(dep.mtime).toBeDefined();
     expect(dep.path).toBeDefined();
+    expect(cacheData).toBeDefined();
+    expect(cacheData.remainingRequest).toBeDefined();
+    expect(cacheData.source).toBeDefined();
+    expect(cacheData.dependencies).toBeDefined();
+    expect(cacheData.contextDependencies).toBeDefined();
+    expect(cacheData.result).toBeDefined();
   });
 
   it('should call compare with contextualized dep', async () => {

test/helpers.js

@@ -58,7 +58,7 @@ function compile(fixture, config = {}, options = {}) {
   // eslint-disable-next-line no-param-reassign
   config = {
     mode: 'development',
-    devtool: config.devtool || 'sourcemap',
+    devtool: config.devtool || 'source-map',
     context: path.resolve(__dirname, 'fixtures'),
     entry: path.resolve(__dirname, 'fixtures', fixture),
     output: outputConfig(config),