Fix PostCSS plugin ignoring .stylelintignore

lib/isPathIgnored.js

@@ -1,6 +1,8 @@
 /* @flow */
 "use strict";
 
+const filterFilePaths = require("./utils/filterFilePaths");
+const getFileIgnorer = require("./utils/getFileIgnorer");
 const micromatch = require("micromatch");
 const path = require("path");
 const slash = require("slash");
@@ -18,6 +20,9 @@ module.exports = function(
     return Promise.resolve(false);
   }
 
+  const cwd = process.cwd();
+  const ignorer = getFileIgnorer(stylelint._options);
+
   return stylelint.getConfigForFile(filePath).then(result => {
     // Glob patterns for micromatch should be in POSIX-style
     const ignoreFiles = (result.config.ignoreFiles || []).map(slash);
@@ -30,6 +35,14 @@ module.exports = function(
       return true;
     }
 
+    // Check filePath with .stylelintignore file
+    if (
+      filterFilePaths(ignorer, [path.relative(cwd, absoluteFilePath)])
+        .length === 0
+    ) {
+      return true;
+    }
+
     return false;
   });
 };

lib/standalone.js

@@ -99,6 +99,7 @@ module.exports = function(
     configBasedir,
     configOverrides,
     ignoreDisables,
+    ignorePath: ignoreFilePath,
     reportNeedlessDisables,
     syntax,
     customSyntax,

lib/utils/getFileIgnorer.js

@@ -0,0 +1,30 @@
+"use strict";
+// Try to get file ignorer from '.stylelintignore'
+
+const fs = require("fs");
+const ignore = require("ignore");
+const path = require("path");
+
+const DEFAULT_IGNORE_FILENAME = ".stylelintignore";
+const FILE_NOT_FOUND_ERROR_CODE = "ENOENT";
+
+module.exports = function(options /*: stylelint$standaloneOptions */) {
+  const ignoreFilePath = options.ignorePath || DEFAULT_IGNORE_FILENAME;
+  const absoluteIgnoreFilePath = path.isAbsolute(ignoreFilePath)
+    ? ignoreFilePath
+    : path.resolve(process.cwd(), ignoreFilePath);
+  let ignoreText = "";
+
+  try {
+    ignoreText = fs.readFileSync(absoluteIgnoreFilePath, "utf8");
+  } catch (readError) {
+    if (readError.code !== FILE_NOT_FOUND_ERROR_CODE) throw readError;
+  }
+
+  const ignorePattern = options.ignorePattern || [];
+  const ignorer = ignore()
+    .add(ignoreText)
+    .add(ignorePattern);
+
+  return ignorer;
+};