feat: invoke eslint as a process to pass arguments

README.md

@@ -11,7 +11,25 @@ In your Bitbucket Pipeline or Github Action, instead of `npx eslint .`:
 npx eslint-pullrequest
 ```
 
-It will use your existing ESLint configuration, but will attempt to lint all files in the pull request that have the extensions defined in the `LINTABLE_EXTENSIONS` environment variable. The default value is `.js,.ts,.jsx,.tsx`.
+### Arguments
+
+Any flags passed to _eslint-pullrequest_ will be passed to ESLint. See [ESLint CLI reference](https://eslint.org/docs/latest/use/command-line-interface) for inspiration.
+
+For example:
+
+```
+npx eslint-pullrequest --format compact
+```
+
+### Environment variables
+
+#### `LINTABLE_EXTENSIONS`
+
+_eslint-pullrequest_ will use your existing ESLint configuration, but because of how ESLint file matching works it will only attempt to lint files involved in the pull request that have the extensions defined in the `LINTABLE_EXTENSIONS` environment variable. The default value is `.js,.ts,.jsx,.tsx`.
+
+#### `MAX_EXEC_BUFFER_MB`
+
+The size of the buffer that holds ESLints terminal output. Normally you shouldn't have to change this value unless you have hundreds or thousands of linting errors. The default is `10`.
 
 ## License
 

bin/cli.ts

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 
 import { getLintableFiles } from '../src/index'
-import { ESLint } from 'eslint'
+import execute from '../src/utils/execute'
 
 const {
   LINTABLE_EXTENSIONS = '.js,.ts,.jsx,.tsx',
@@ -11,19 +11,25 @@ const {
   const lintableExtensions = LINTABLE_EXTENSIONS.split(',')
   const lintableFiles = await getLintableFiles(lintableExtensions)
 
-  const eslint = new ESLint()
-  const results = await eslint.lintFiles(lintableFiles)
+  const eslintArguments = [
+    // proxy any command-line arguments we received
+    ...process.argv.slice(2),
+    ...lintableFiles,
+  ]
+    .filter(Boolean)
+    .join(' ')
 
-  // eslint-disable-next-line @typescript-eslint/restrict-plus-operands
-  const errorCount = results.reduce((sum, { errorCount }) => { return sum + errorCount }, 0)
-
-  if (errorCount) {
-    const formatter = await eslint.loadFormatter()
-    const resultText = formatter.format(results)
-    console.log(resultText)
-
-    process.exit(1)
-  }
+  await execute(`npx eslint ${eslintArguments}`)
+    .catch(err => {
+      // ExecException will have a code
+      if (err.code) {
+        console.error(err)
+        process.exit(err.code)
+      }
+      // assume any other output is from eslint
+      console.log(err.message)
+      process.exit(1)
+    })
 })().catch(err => {
   console.error(err)
   process.exit(1)

src/utils/execute.ts

@@ -0,0 +1,27 @@
+import { exec } from 'child_process'
+
+const {
+  MAX_EXEC_BUFFER_MB = '10',
+} = process.env
+
+const maxBuffer = 1024 * 1024 * parseFloat(MAX_EXEC_BUFFER_MB)
+
+export default async (command: string): Promise<string> => await new Promise((resolve, reject) => {
+  exec(`cd "${process.cwd()}" && ${command}`, { shell: 'bash', maxBuffer }, (err, stdout, stderr) => {
+    if (err) {
+      // when `command` itself fails its error will be printed to stderr
+      if (stderr) {
+        return reject(new Error(stderr))
+      }
+      // some apps (eslint) uses stdout even for errors
+      // lets assume that exitcode 1 means there is a meaningful error from the command itself
+      if (!err.killed && err.code === 1) {
+        return reject(new Error(stdout))
+      }
+      // when child_process.exec fails the source error will be in `err`
+      return reject(err)
+    }
+
+    return resolve(stdout)
+  })
+})