Standardize and improve exit code handling (#245)

README.md

@@ -112,9 +112,10 @@ If a rule is passed to both `--enable` and `--disable`, it will be disabled.
 `markdownlint-cli` returns one of the following exit codes:
 
 - `0`: Program ran successfully
-- `1`: Linting errors / bad parameter
+- `1`: Linting errors
 - `2`: Unable to write `-o`/`--output` output file
 - `3`: Unable to load `-r`/`--rules` custom rule
+- `4`: Unexpected error (e.g. malformed config)
 
 ## Use with pre-commit
 

markdownlint.js

@@ -24,6 +24,13 @@ function jsYamlSafeLoad(text) {
   return require('js-yaml').load(text);
 }
 
+const exitCodes = {
+  lintFindings: 1,
+  failedToWriteOutputFile: 2,
+  failedToLoadCustomRules: 3,
+  unexpectedError: 4
+};
+
 const projectConfigFiles = [
   '.markdownlint.json',
   '.markdownlint.yaml',
@@ -61,7 +68,7 @@ function readConfiguration(userConfigFile) {
       config = require('deep-extend')(config, userConfig);
     } catch (error) {
       console.error(`Cannot read or parse config file '${userConfigFile}': ${error.message}`);
-      process.exitCode = 1;
+      process.exitCode = exitCodes.unexpectedError;
     }
   }
 
@@ -160,7 +167,7 @@ function printResult(lintResult) {
     // and let the program terminate normally.
     // @see {@link https://nodejs.org/dist/latest-v8.x/docs/api/process.html#process_process_exit_code}
     // @see {@link https://github.com/igorshubovych/markdownlint-cli/pull/29#issuecomment-343535291}
-    process.exitCode = 1;
+    process.exitCode = exitCodes.lintFindings;
   }
 
   if (options.output) {
@@ -171,7 +178,7 @@ function printResult(lintResult) {
       fs.writeFileSync(options.output, lintResultString);
     } catch (error) {
       console.warn('Cannot write to output file ' + options.output + ': ' + error.message);
-      process.exitCode = 2;
+      process.exitCode = exitCodes.failedToWriteOutputFile;
     }
   } else if (lintResultString && !options.quiet) {
     console.error(lintResultString);
@@ -239,7 +246,7 @@ function loadCustomRules(rules) {
       return fileList;
     } catch (error) {
       console.error('Cannot load custom rule ' + rule + ': ' + error.message);
-      return process.exit(3);
+      return process.exit(exitCodes.failedToLoadCustomRules);
     }
   });
 }
@@ -321,11 +328,16 @@ function lintAndPrint(stdin, files) {
   printResult(lintResult);
 }
 
-if ((files.length > 0) && !options.stdin) {
-  lintAndPrint(null, diff);
-} else if ((files.length === 0) && options.stdin && !options.fix) {
-  const getStdin = require('get-stdin');
-  getStdin().then(lintAndPrint);
-} else {
-  program.help();
+try {
+  if ((files.length > 0) && !options.stdin) {
+    lintAndPrint(null, diff);
+  } else if ((files.length === 0) && options.stdin && !options.fix) {
+    const getStdin = require('get-stdin');
+    getStdin().then(lintAndPrint);
+  } else {
+    program.help();
+  }
+} catch (error) {
+  console.error(error);
+  process.exit(exitCodes.unexpectedError);
 }

test/test.js

@@ -126,6 +126,22 @@ test('linting of incorrect Markdown file fails with absolute path', async t => {
   }
 });
 
+test('linting of unreadable Markdown file fails', async t => {
+  const unreadablePath = '../unreadable.test.md';
+  fs.symlinkSync('nonexistent.dest.md', unreadablePath, 'file');
+
+  try {
+    await execa('../markdownlint.js',
+      ['--config', 'test-config.json', unreadablePath],
+      {stripFinalNewline: false});
+    t.fail();
+  } catch (error) {
+    t.is(error.exitCode, 4);
+  } finally {
+    fs.unlinkSync(unreadablePath, {force: true});
+  }
+});
+
 test('linting of incorrect Markdown via npm run file fails with eol', async t => {
   try {
     await execa('npm', ['run', 'invalid'], {stripFinalNewline: false});
@@ -472,7 +488,7 @@ test('error on configuration file not found', async t => {
   } catch (error) {
     t.is(error.stdout, '');
     t.regex(error.stderr, /Cannot read or parse config file 'non-existent-file-path.yaml': ENOENT: no such file or directory, open 'non-existent-file-path.yaml'/);
-    t.is(error.exitCode, 1);
+    t.is(error.exitCode, 4);
   }
 });
 
@@ -484,7 +500,7 @@ test('error on malformed YAML configuration file', async t => {
   } catch (error) {
     t.is(error.stdout, '');
     t.regex(error.stderr, /Cannot read or parse config file 'malformed-config.yaml': Unable to parse 'malformed-config.yaml'; Unexpected token/);
-    t.is(error.exitCode, 1);
+    t.is(error.exitCode, 4);
   }
 });