Issue #30 - add lint dirty files only flag

README.md

@@ -42,10 +42,11 @@ See [stylelint options](http://stylelint.io/user-guide/node-api/#options) for th
 
 * `configFile`: You can change the config file location. Default: (`undefined`), handled by [stylelint's cosmiconfig module](http://stylelint.io/user-guide/configuration/).
 * `context`: String indicating the root of your SCSS files. Default: inherits from webpack config.
+* `failOnError`: Have Webpack's build process die on error. Default: `false`
 * `files`: Change the glob pattern for finding files. Default: (`['**/*.s?(a|c)ss']`)
-* `syntax`: Use `'scss'` to lint .scss files. Default (`undefined`)
 * `formatter`: Use a custom formatter to print errors to the console. Default: (`require('stylelint').formatters.string`)
-* `failOnError`: Have Webpack's build process die on error. Default: `false`
+* `lintDirtyModulesOnly`: Lint only changed files, skip lint on start. Default (`false`)
+* `syntax`: Use `'scss'` to lint .scss files. Default (`undefined`)
 * `quiet`: Don't print stylelint output to the console. Default: `false`
 
 ## Errors

index.js

@@ -8,11 +8,11 @@ var formatter = require('stylelint').formatters.string;
 
 // Modules
 var runCompilation = require('./lib/run-compilation');
+var LintDirtyModulesPlugin = require('./lib/lint-dirty-modules-plugin');
 
 function apply (options, compiler) {
   options = options || {};
   var context = options.context || compiler.context;
-
   options = assign({
     formatter: formatter,
     quiet: false
@@ -27,10 +27,14 @@ function apply (options, compiler) {
 
   var runner = runCompilation.bind(this, options);
 
-  compiler.plugin('run', runner);
-  compiler.plugin('watch-run', function onWatchRun (watcher, callback) {
-    runner(watcher.compiler, callback);
-  });
+  if (options.lintDirtyModulesOnly) {
+    new LintDirtyModulesPlugin(compiler, options); // eslint-disable-line no-new
+  } else {
+    compiler.plugin('run', runner);
+    compiler.plugin('watch-run', function onWatchRun (watcher, callback) {
+      runner(watcher.compiler, callback);
+    });
+  }
 }
 
 /**

lib/lint-dirty-modules-plugin.js

@@ -0,0 +1,74 @@
+'use strict';
+var minimatch = require('minimatch');
+var reduce = require('lodash.reduce');
+var assign = require('object-assign');
+var runCompilation = require('./run-compilation');
+
+/**
+ * Binds callback with provided options and stores initial values.
+ *
+ * @param compiler - webpack compiler object
+ * @param options - stylelint nodejs options
+ * @param callback <function(options, compilitaion)> - callback to call on emit
+ */
+function LintDirtyModulesPlugin (compiler, options) {
+  this.startTime = Date.now();
+  this.prevTimestamps = {};
+  this.isFirstRun = true;
+  this.compiler = compiler;
+  this.options = options;
+  compiler.plugin('emit',
+    this.lint.bind(this) // bind(this) is here to prevent context overriding by webpack
+  );
+}
+
+/**
+ * Lints changed files provided by compilation object.
+ * Fully executed only after initial run.
+ *
+ * @param options - stylelint options
+ * @param compilation - webpack compilation object
+ * @param callback - to be called when execution is done
+ * @returns {*}
+ */
+LintDirtyModulesPlugin.prototype.lint = function (compilation, callback) {
+  if (this.isFirstRun) {
+    this.isFirstRun = false;
+    this.prevTimestamps = compilation.fileTimestamps;
+    return callback();
+  }
+  var dirtyOptions = assign({}, this.options);
+  var glob = dirtyOptions.files.join('|');
+  var changedFiles = this.getChangedFiles(compilation.fileTimestamps, glob);
+  this.prevTimestamps = compilation.fileTimestamps;
+  if (changedFiles.length) {
+    dirtyOptions.files = changedFiles;
+    runCompilation.call(this, dirtyOptions, this.compiler, callback);
+  } else {
+    callback();
+  }
+};
+
+/**
+ * Returns an array of changed files comparing current timestamps
+ * against cached timestamps from previous run.
+ *
+ * @param plugin - stylelint-webpack-plugin this scopr
+ * @param fileTimestamps - an object with keys as filenames and values as their timestamps.
+ * e.g. {'/filename.scss': 12444222000}
+ * @param glob - glob pattern to match files
+ */
+LintDirtyModulesPlugin.prototype.getChangedFiles = function (fileTimestamps, glob) {
+  return reduce(fileTimestamps, function (changedStyleFiles, timestamp, filename) {
+    // Check if file has been changed first ...
+    if ((this.prevTimestamps[filename] || this.startTime) < (fileTimestamps[filename] || Infinity) &&
+      // ... then validate by the glob pattern.
+      minimatch(filename, glob, {matchBase: true})
+    ) {
+      changedStyleFiles = changedStyleFiles.concat(filename);
+    }
+    return changedStyleFiles;
+  }.bind(this), []);
+};
+
+module.exports = LintDirtyModulesPlugin;

lib/run-compilation.js

@@ -38,7 +38,7 @@ module.exports = function runCompilation (options, compiler, done) {
     })
     .catch(done);
 
-  compiler.plugin('compilation', function onCompilation (compilation) {
+  compiler.plugin('after-emit', function onCompilation (compilation, callback) {
     if (warnings.length) {
       compilation.warnings.push(chalk.yellow(options.formatter(warnings)));
       warnings = [];
@@ -48,5 +48,7 @@ module.exports = function runCompilation (options, compiler, done) {
       compilation.errors.push(chalk.red(options.formatter(errors)));
       errors = [];
     }
+
+    callback();
   });
 };

package.json

@@ -33,6 +33,8 @@
   "dependencies": {
     "arrify": "^1.0.1",
     "chalk": "^1.1.3",
+    "lodash.reduce": "^4.6.0",
+    "minimatch": "^3.0.3",
     "object-assign": "^4.1.0",
     "stylelint": "^7.7.0"
   },
@@ -45,7 +47,8 @@
     "mocha": "^3.1.0",
     "npm-install-version": "^6.0.1",
     "nyc": "^10.0.0",
-    "semistandard": "^9.2.1"
+    "semistandard": "^9.2.1",
+    "testdouble": "^1.10.2"
   },
   "scripts": {
     "pretest": "semistandard",

test/index.js

@@ -1,13 +1,13 @@
 'use strict';
 
 var assign = require('object-assign');
-
 var StyleLintPlugin = require('../');
 var pack = require('./helpers/pack');
 var webpack = require('./helpers/webpack');
 var baseConfig = require('./helpers/base-config');
 
 var configFilePath = getPath('./.stylelintrc');
+require('./lib/lint-dirty-modules-plugin');
 
 describe('stylelint-webpack-plugin', function () {
   it('works with a simple file', function () {
@@ -106,7 +106,8 @@ describe('stylelint-webpack-plugin', function () {
       entry: './index',
       plugins: [
         new StyleLintPlugin({
-          configFile: configFilePath
+          configFile: configFilePath,
+          quiet: true
         })
       ]
     };
@@ -177,4 +178,27 @@ describe('stylelint-webpack-plugin', function () {
         expect(err.message).to.contain('Failed to parse').and.contain('as JSON');
       });
   });
+
+  context('lintDirtyModulesOnly flag is enabled', function () {
+    it('skips linting on initial run', function () {
+      var config = {
+        context: './test/fixtures/test3',
+        entry: './index',
+        plugins: [
+          new StyleLintPlugin({
+            configFile: configFilePath,
+            quiet: true,
+            lintDirtyModulesOnly: true
+          }),
+          new webpack.NoErrorsPlugin()
+        ]
+      };
+
+      return pack(assign({}, baseConfig, config))
+        .then(function (stats) {
+          expect(stats.compilation.errors).to.have.length(0);
+          expect(stats.compilation.warnings).to.have.length(0);
+        });
+    });
+  });
 });

test/lib/lint-dirty-modules-plugin.js

@@ -0,0 +1,141 @@
+'use strict';
+
+var td = require('testdouble');
+var formatter = require('stylelint').formatters.string;
+
+var runCompilation = td.replace('../../lib/run-compilation');
+
+var LintDirtyModulesPlugin = require('../../lib/lint-dirty-modules-plugin');
+
+var configFilePath = getPath('./.stylelintrc');
+var glob = '/**/*.s?(c|a)ss';
+
+describe('lint-dirty-modules-plugin', function () {
+  context('lintDirtyModulesOnly flag is enabled', function () {
+    var LintDirtyModulesPluginCloned;
+    var compilerMock;
+    var optionsMock;
+
+    beforeEach(function () {
+      LintDirtyModulesPluginCloned = function () {
+        LintDirtyModulesPlugin.apply(this, arguments);
+      };
+      LintDirtyModulesPluginCloned.prototype = Object.create(LintDirtyModulesPlugin.prototype);
+      LintDirtyModulesPluginCloned.prototype.constructor = LintDirtyModulesPlugin;
+
+      compilerMock = {
+        callback: null,
+        plugin: function plugin (event, callback) {
+          this.callback = callback;
+        }
+      };
+
+      optionsMock = {
+        configFile: configFilePath,
+        lintDirtyModulesOnly: true,
+        fomatter: formatter,
+        files: [glob]
+      };
+    });
+
+    it('lint is called on \'emit\'', function () {
+      var lintStub = td.function();
+      var doneStub = td.function();
+      LintDirtyModulesPluginCloned.prototype.lint = lintStub;
+      var plugin = new LintDirtyModulesPluginCloned(compilerMock, optionsMock);
+
+      var compilationMock = {
+        fileTimestamps: {
+          '/udpated.scss': 5
+        }
+      };
+      compilerMock.callback(compilationMock, doneStub);
+
+      expect(plugin.isFirstRun).to.eql(true);
+      td.verify(lintStub(compilationMock, doneStub));
+    });
+
+    context('LintDirtyModulesPlugin.prototype.lint()', function () {
+      var getChangedFilesStub;
+      var doneStub;
+      var compilationMock;
+      var fileTimestamps = {
+        '/test/changed.scss': 5,
+        '/test/newly-created.scss': 5
+      };
+      var pluginMock;
+      beforeEach(function () {
+        getChangedFilesStub = td.function();
+        doneStub = td.function();
+        compilationMock = {
+          fileTimestamps: {}
+        };
+        td.when(getChangedFilesStub({}, glob)).thenReturn([]);
+        td.when(getChangedFilesStub(fileTimestamps, glob)).thenReturn(Object.keys(fileTimestamps));
+        pluginMock = {
+          getChangedFiles: getChangedFilesStub,
+          compiler: compilerMock,
+          options: optionsMock,
+          isFirstRun: true
+        };
+      });
+
+      it('skips compilation on first run', function () {
+        expect(pluginMock.isFirstRun).to.eql(true);
+        LintDirtyModulesPluginCloned.prototype.lint.call(pluginMock, compilationMock, doneStub);
+        td.verify(doneStub());
+        expect(pluginMock.isFirstRun).to.eql(false);
+        td.verify(getChangedFilesStub, {times: 0, ignoreExtraArgs: true});
+        td.verify(runCompilation, {times: 0, ignoreExtraArgs: true});
+      });
+
+      it('runCompilation is not called if files are not changed', function () {
+        pluginMock.isFirstRun = false;
+        LintDirtyModulesPluginCloned.prototype.lint.call(pluginMock, compilationMock, doneStub);
+        td.verify(doneStub());
+        td.verify(runCompilation, {times: 0, ignoreExtraArgs: true});
+      });
+
+      it('runCompilation is called if styles are changed', function () {
+        pluginMock.isFirstRun = false;
+        compilationMock = {
+          fileTimestamps: fileTimestamps
+        };
+        LintDirtyModulesPluginCloned.prototype.lint.call(pluginMock, compilationMock, doneStub);
+        optionsMock.files = Object.keys(fileTimestamps);
+        td.verify(runCompilation(optionsMock, compilerMock, doneStub));
+      });
+    });
+
+    context('LintDirtyModulesPlugin.prototype.getChangedFiles()', function () {
+      var pluginMock;
+      before(function () {
+        pluginMock = {
+          compiler: compilerMock,
+          options: optionsMock,
+          isFirstRun: true,
+          startTime: 10,
+          prevTimestamps: {
+            '/test/changed.scss': 5,
+            '/test/removed.scss': 5,
+            '/test/changed.js': 5
+          }
+        };
+      });
+      it('returns changed style files', function () {
+        var fileTimestamps = {
+          '/test/changed.scss': 20,
+          '/test/changed.js': 20,
+          '/test/newly-created.scss': 15
+        };
+
+        expect(
+          LintDirtyModulesPluginCloned.prototype.getChangedFiles.call(pluginMock, fileTimestamps, glob)).to.eql([
+            '/test/changed.scss',
+            '/test/newly-created.scss'
+          ]
+        );
+      });
+    });
+  });
+});