Refactor to move parseConfiguration function into a separate file, add stronger typing, add first test case.

lib/markdownlint.mjs

@@ -8,6 +8,7 @@ import { requireMarkdownItCjs } from "./defer-require.cjs";
 import { resolveModule } from "./resolve-module.cjs";
 import rules from "./rules.mjs";
 import { parse as micromarkParse } from "./micromark-parse.mjs";
+import parseConfiguration from "./parse-configuration.mjs";
 import * as helpers from "../helpers/helpers.cjs";
 
 /**
@@ -268,39 +269,6 @@ function getEffectiveConfig(ruleList, config, aliasToRuleNames) {
   return effectiveConfig;
 }
 
-/**
- * Parse the content of a configuration file.
- *
- * @param {string} name Name of the configuration file.
- * @param {string} content Configuration content.
- * @param {ConfigurationParser[] | null} [parsers] Parsing function(s).
- * @returns {Object} Configuration object and error message.
- */
-function parseConfiguration(name, content, parsers) {
-  let config = null;
-  let message = "";
-  const errors = [];
-  let index = 0;
-  // Try each parser
-  (parsers || [ JSON.parse ]).every((parser) => {
-    try {
-      config = parser(content);
-    } catch (error) {
-      errors.push(`Parser ${index++}: ${error.message}`);
-    }
-    return !config;
-  });
-  // Message if unable to parse
-  if (!config) {
-    errors.unshift(`Unable to parse '${name}'`);
-    message = errors.join("; ");
-  }
-  return {
-    config,
-    message
-  };
-}
-
 /**
  * Create a mapping of enabled rules per line.
  *
@@ -309,7 +277,7 @@ function parseConfiguration(name, content, parsers) {
  * @param {string[]} frontMatterLines List of front matter lines.
  * @param {boolean} noInlineConfig Whether to allow inline configuration.
  * @param {Configuration} config Configuration object.
- * @param {ConfigurationParser[] | null} configParsers Configuration parsers.
+ * @param {ConfigurationParser[] | undefined} configParsers Configuration parsers.
  * @param {Object.<string, string[]>} aliasToRuleNames Map of alias to rule
  * names.
  * @returns {Object} Effective configuration and enabled rules per line number.
@@ -448,7 +416,7 @@ function getEnabledRulesPerLineNumber(
  * @param {string} content Markdown content.
  * @param {MarkdownItFactory} markdownItFactory Function to create a markdown-it parser.
  * @param {Configuration} config Configuration object.
- * @param {ConfigurationParser[] | null} configParsers Configuration parsers.
+ * @param {ConfigurationParser[] | undefined} configParsers Configuration parsers.
  * @param {RegExp | null} frontMatter Regular expression for front matter.
  * @param {boolean} handleRuleFailures Whether to handle exceptions in rules.
  * @param {boolean} noInlineConfig Whether to allow inline configuration.
@@ -776,7 +744,7 @@ function lintContent(
  * @param {string} file Path of file to lint.
  * @param {MarkdownItFactory} markdownItFactory Function to create a markdown-it parser.
  * @param {Configuration} config Configuration object.
- * @param {ConfigurationParser[] | null} configParsers Configuration parsers.
+ * @param {ConfigurationParser[] | undefined} configParsers Configuration parsers.
  * @param {RegExp | null} frontMatter Regular expression for front matter.
  * @param {boolean} handleRuleFailures Whether to handle exceptions in rules.
  * @param {boolean} noInlineConfig Whether to allow inline configuration.
@@ -869,7 +837,7 @@ function lintInput(options, synchronous, callback) {
   const strings = options.strings || {};
   const stringsKeys = Object.keys(strings);
   const config = options.config || { "default": true };
-  const configParsers = options.configParsers || null;
+  const configParsers = options.configParsers || undefined;
   const frontMatter = (options.frontMatter === undefined) ?
     helpers.frontMatterRe :
     options.frontMatter;

lib/parse-configuration.mjs

@@ -0,0 +1,42 @@
+// @ts-check
+
+/**
+ * Result of a call to parseConfiguration.
+ *
+ * @typedef {Object} ParseConfigurationResult
+ * @property {Object | null} config Configuration object if successful.
+ * @property {string} message Error message if an error occurred.
+ */
+
+/**
+ * Parse the content of a configuration file.
+ *
+ * @param {string} name Name of the configuration file.
+ * @param {string} content Configuration content.
+ * @param {import("./markdownlint.mjs").ConfigurationParser[]} [parsers] Parsing function(s).
+ * @returns {ParseConfigurationResult} Parse configuration result.
+ */
+export default function parseConfiguration(name, content, parsers) {
+  let config = null;
+  let message = "";
+  const errors = [];
+  let index = 0;
+  // Try each parser
+  (parsers || [ JSON.parse ]).every((parser) => {
+    try {
+      config = parser(content);
+    } catch (error) {
+      errors.push(`Parser ${index++}: ${error.message}`);
+    }
+    return !config;
+  });
+  // Message if unable to parse
+  if (!config) {
+    errors.unshift(`Unable to parse '${name}'`);
+    message = errors.join("; ");
+  }
+  return {
+    config,
+    message
+  };
+}

package.json

@@ -59,7 +59,7 @@
     "lint-test-repos": "ava --timeout=10m test/markdownlint-test-repos-*.mjs",
     "serial-config-docs": "npm run build-config && npm run build-docs",
     "serial-declaration": "npm run build-declaration && npm run test-declaration",
-    "test": "ava --timeout=30s test/markdownlint-test.mjs test/markdownlint-test-config.mjs test/markdownlint-test-custom-rules.mjs test/markdownlint-test-fixes.mjs test/markdownlint-test-helpers.mjs test/markdownlint-test-micromark.mjs test/markdownlint-test-result-object.mjs test/markdownlint-test-scenarios.mjs test/resolve-module-test.mjs helpers/test.cjs",
+    "test": "ava --timeout=30s test/markdownlint-test.mjs test/markdownlint-test-config.mjs test/markdownlint-test-custom-rules.mjs test/markdownlint-test-fixes.mjs test/markdownlint-test-helpers.mjs test/markdownlint-test-micromark.mjs test/markdownlint-test-result-object.mjs test/markdownlint-test-scenarios.mjs test/parse-configuration-test.mjs test/resolve-module-test.mjs helpers/test.cjs",
     "test-cover": "c8 --100 npm test",
     "test-declaration": "npm-run-all --continue-on-error --parallel test-declaration-cts test-declaration-mts",
     "test-declaration-cts": "cd example/typescript && node ../../scripts/index.mjs copy type-check.ts type-check-commonjs.cts && tsc --module commonjs --esModuleInterop type-check-commonjs.cts",

test/parse-configuration-test.mjs

@@ -0,0 +1,24 @@
+// @ts-check
+
+import test from "ava";
+import parseConfiguration from "../lib/parse-configuration.mjs";
+
+const testObject = {
+  "string": "text",
+  "number": 10,
+  "object": {
+    "property": "value"
+  },
+  "array": [ 1, 2, 3 ]
+};
+const successfulTestObjectResult = {
+  "config": testObject,
+  "message": ""
+};
+const testObjectJsonString = JSON.stringify(testObject);
+
+test("json object, default parsers", (t) => {
+  t.plan(1);
+  const actual = parseConfiguration("name", testObjectJsonString);
+  t.deepEqual(actual, successfulTestObjectResult);
+});