Update readConfig to use fs.access so the async path is fully async.

README.md

@@ -649,7 +649,7 @@ In advanced scenarios, it may be desirable to bypass the default file system API
 If a custom file system implementation is provided, `markdownlint` will use that
 instead of invoking `require("fs")`.
 
-Note: The only methods called are `readFile`, `readFileSync`, and `accessSync`.
+Note: The only methods called are `readFile`, `readFileSync`, `access`, and `accessSync`.
 
 #### callback
 

demo/markdownlint-browser.js

@@ -1638,6 +1638,33 @@ function parseConfiguration(name, content, parsers) {
         message: message
     };
 }
+/**
+ * Resolve referenced "extends" path in a configuration file
+ * using path.resolve() with require.resolve() as a fallback.
+ *
+ * @param {string} configFile Configuration file name.
+ * @param {string} referenceId Referenced identifier to resolve.
+ * @param {Object} fs File system implementation.
+ * @param {ResolveConfigExtendsCallback} [callback] Callback (err, result)
+ * function.
+ * @returns {void}
+ */
+function resolveConfigExtends(configFile, referenceId, fs, callback) {
+    var configFileDirname = path.dirname(configFile);
+    var resolvedExtendsFile = path.resolve(configFileDirname, referenceId);
+    fs.access(resolvedExtendsFile, function (err) {
+        if (err) {
+            // Not a file, try require.resolve
+            try {
+                return callback(null, dynamicRequire.resolve(referenceId, { "paths": [configFileDirname] }));
+            }
+            catch (_a) {
+                // Unable to resolve, use resolvedExtendsFile
+            }
+        }
+        return callback(null, resolvedExtendsFile);
+    });
+}
 /**
  * Resolve referenced "extends" path in a configuration file
  * using path.resolve() with require.resolve() as a fallback.
@@ -1647,7 +1674,7 @@ function parseConfiguration(name, content, parsers) {
  * @param {Object} fs File system implementation.
  * @returns {string} Resolved path to file.
  */
-function resolveConfigExtends(configFile, referenceId, fs) {
+function resolveConfigExtendsSync(configFile, referenceId, fs) {
     var configFileDirname = path.dirname(configFile);
     var resolvedExtendsFile = path.resolve(configFileDirname, referenceId);
     try {
@@ -1705,13 +1732,12 @@ function readConfig(file, parsers, fs, callback) {
         var configExtends = config["extends"];
         if (configExtends) {
             delete config["extends"];
-            var resolvedExtends = resolveConfigExtends(file, configExtends, fs);
-            return readConfig(resolvedExtends, parsers, fs, function (errr, extendsConfig) {
+            return resolveConfigExtends(file, configExtends, fs, function (_, resolvedExtends) { return readConfig(resolvedExtends, parsers, fs, function (errr, extendsConfig) {
                 if (errr) {
                     return callback(errr);
                 }
                 return callback(null, __assign(__assign({}, extendsConfig), config));
-            });
+            }); });
         }
         return callback(null, config);
     });
@@ -1752,7 +1778,7 @@ function readConfigSync(file, parsers, fs) {
     var configExtends = config["extends"];
     if (configExtends) {
         delete config["extends"];
-        var resolvedExtends = resolveConfigExtends(file, configExtends, fs);
+        var resolvedExtends = resolveConfigExtendsSync(file, configExtends, fs);
         return __assign(__assign({}, readConfigSync(resolvedExtends, parsers, fs)), config);
     }
     return config;

lib/markdownlint.d.ts

@@ -8,7 +8,7 @@ export = markdownlint;
  */
 declare function markdownlint(options: Options, callback: LintCallback): void;
 declare namespace markdownlint {
-    export { markdownlintSync as sync, readConfig, readConfigSync, getVersion, promises, RuleFunction, RuleParams, MarkdownItToken, RuleOnError, RuleOnErrorInfo, RuleOnErrorFixInfo, Rule, Options, Plugin, ToStringCallback, LintResults, LintError, FixInfo, LintCallback, Configuration, RuleConfiguration, ConfigurationParser, ReadConfigCallback };
+    export { markdownlintSync as sync, readConfig, readConfigSync, getVersion, promises, RuleFunction, RuleParams, MarkdownItToken, RuleOnError, RuleOnErrorInfo, RuleOnErrorFixInfo, Rule, Options, Plugin, ToStringCallback, LintResults, LintError, FixInfo, LintCallback, Configuration, RuleConfiguration, ConfigurationParser, ReadConfigCallback, ResolveConfigExtendsCallback };
 }
 /**
  * Configuration options.
@@ -58,7 +58,7 @@ type Options = {
     fs?: any;
 };
 /**
- * Called with the result of the lint operation.
+ * Called with the result of the lint function.
  */
 type LintCallback = (err: Error | null, results?: LintResults) => void;
 /**
@@ -355,9 +355,13 @@ type RuleConfiguration = boolean | any;
  */
 type ConfigurationParser = (text: string) => Configuration;
 /**
- * Called with the result of the readConfig operation.
+ * Called with the result of the readConfig function.
  */
 type ReadConfigCallback = (err: Error | null, config?: Configuration) => void;
+/**
+ * Called with the result of the resolveConfigExtends function.
+ */
+type ResolveConfigExtendsCallback = (err: Error | null, path?: string) => void;
 /**
  * Lint specified Markdown files.
  *

lib/markdownlint.js

@@ -926,6 +926,36 @@ function parseConfiguration(name, content, parsers) {
   };
 }
 
+/**
+ * Resolve referenced "extends" path in a configuration file
+ * using path.resolve() with require.resolve() as a fallback.
+ *
+ * @param {string} configFile Configuration file name.
+ * @param {string} referenceId Referenced identifier to resolve.
+ * @param {Object} fs File system implementation.
+ * @param {ResolveConfigExtendsCallback} [callback] Callback (err, result)
+ * function.
+ * @returns {void}
+ */
+function resolveConfigExtends(configFile, referenceId, fs, callback) {
+  const configFileDirname = path.dirname(configFile);
+  const resolvedExtendsFile = path.resolve(configFileDirname, referenceId);
+  fs.access(resolvedExtendsFile, (err) => {
+    if (err) {
+      // Not a file, try require.resolve
+      try {
+        return callback(null, dynamicRequire.resolve(
+          referenceId,
+          { "paths": [ configFileDirname ] }
+        ));
+      } catch {
+        // Unable to resolve, use resolvedExtendsFile
+      }
+    }
+    return callback(null, resolvedExtendsFile);
+  });
+}
+
 /**
  * Resolve referenced "extends" path in a configuration file
  * using path.resolve() with require.resolve() as a fallback.
@@ -935,7 +965,7 @@ function parseConfiguration(name, content, parsers) {
  * @param {Object} fs File system implementation.
  * @returns {string} Resolved path to file.
  */
-function resolveConfigExtends(configFile, referenceId, fs) {
+function resolveConfigExtendsSync(configFile, referenceId, fs) {
   const configFileDirname = path.dirname(configFile);
   const resolvedExtendsFile = path.resolve(configFileDirname, referenceId);
   try {
@@ -994,8 +1024,15 @@ function readConfig(file, parsers, fs, callback) {
     const configExtends = config.extends;
     if (configExtends) {
       delete config.extends;
-      const resolvedExtends = resolveConfigExtends(file, configExtends, fs);
-      return readConfig(resolvedExtends, parsers, fs, (errr, extendsConfig) => {
+      return resolveConfigExtends(
+        file,
+        configExtends,
+        fs,
+        (_, resolvedExtends) => readConfig(
+          resolvedExtends,
+          parsers,
+          fs,
+          (errr, extendsConfig) => {
             if (errr) {
               return callback(errr);
             }
@@ -1003,7 +1040,9 @@ function readConfig(file, parsers, fs, callback) {
               ...extendsConfig,
               ...config
             });
-      });
+          }
+        )
+      );
     }
     return callback(null, config);
   });
@@ -1047,7 +1086,7 @@ function readConfigSync(file, parsers, fs) {
   const configExtends = config.extends;
   if (configExtends) {
     delete config.extends;
-    const resolvedExtends = resolveConfigExtends(file, configExtends, fs);
+    const resolvedExtends = resolveConfigExtendsSync(file, configExtends, fs);
     return {
       ...readConfigSync(resolvedExtends, parsers, fs),
       ...config
@@ -1221,7 +1260,7 @@ module.exports = markdownlint;
  */
 
 /**
- * Called with the result of the lint operation.
+ * Called with the result of the lint function.
  *
  * @callback LintCallback
  * @param {Error | null} err Error object or null.
@@ -1251,10 +1290,19 @@ module.exports = markdownlint;
  */
 
 /**
- * Called with the result of the readConfig operation.
+ * Called with the result of the readConfig function.
  *
  * @callback ReadConfigCallback
  * @param {Error | null} err Error object or null.
  * @param {Configuration} [config] Configuration object.
  * @returns {void}
  */
+
+/**
+ * Called with the result of the resolveConfigExtends function.
+ *
+ * @callback ResolveConfigExtendsCallback
+ * @param {Error | null} err Error object or null.
+ * @param {string} [path] Resolved path to file.
+ * @returns {void}
+ */

test/markdownlint-test.js

@@ -1155,8 +1155,9 @@ test.cb("configCustomFileSystem", (t) => {
     "MD002": true
   };
   const fsApi = {
-    "accessSync": (p) => {
-      t.is(p, extended);
+    "access": (p, m, cb) => {
+      t.is(path.resolve(p), extended);
+      return (cb || m)();
     },
     "readFile": (p, o, cb) => {
       switch (p) {
@@ -1455,7 +1456,7 @@ test("configCustomFileSystemSync", (t) => {
   };
   const fsApi = {
     "accessSync": (p) => {
-      t.is(p, extended);
+      t.is(path.resolve(p), extended);
     },
     "readFileSync": (p) => {
       switch (p) {
@@ -1520,8 +1521,9 @@ test.cb("configCustomFileSystemPromise", (t) => {
     "MD002": true
   };
   const fsApi = {
-    "accessSync": (p) => {
-      t.is(p, extended);
+    "access": (p, m, cb) => {
+      t.is(path.resolve(p), extended);
+      return (cb || m)();
     },
     "readFile": (p, o, cb) => {
       switch (p) {