test: add debug logging to getConfigGroups

lib/getConfigGroups.js

@@ -2,10 +2,15 @@
 
 import path from 'path'
 
+import debug from 'debug'
+import objectInspect from 'object-inspect'
+
 import { loadConfig } from './loadConfig.js'
 import { ConfigNotFoundError } from './symbols.js'
 import { validateConfig } from './validateConfig.js'
 
+const debugLog = debug('lint-staged:getConfigGroups')
+
 /**
  * Return matched files grouped by their configuration.
  *
@@ -16,14 +21,19 @@ import { validateConfig } from './validateConfig.js'
  * @param {Logger} logger
  */
 export const getConfigGroups = async ({ configObject, configPath, files }, logger = console) => {
+  debugLog('Grouping configuration files...')
+
   // Return explicit config object from js API
   if (configObject) {
+    debugLog('Using single direct configuration object...')
     const config = validateConfig(configObject, 'config object', logger)
     return { '': { config, files } }
   }
 
   // Use only explicit config path instead of discovering multiple
   if (configPath) {
+    debugLog('Using single configuration path...')
+
     const { config, filepath } = await loadConfig({ configPath }, logger)
 
     if (!config) {
@@ -35,6 +45,8 @@ export const getConfigGroups = async ({ configObject, configPath, files }, logge
     return { [configPath]: { config: validatedConfig, files } }
   }
 
+  debugLog('Grouping staged files by their directories...')
+
   // Group files by their base directory
   const filesByDir = files.reduce((acc, file) => {
     const dir = path.normalize(path.dirname(file))
@@ -48,22 +60,33 @@ export const getConfigGroups = async ({ configObject, configPath, files }, logge
     return acc
   }, {})
 
+  debugLog('Grouped staged files into %d directories:', Object.keys(filesByDir).length)
+  debugLog(objectInspect(filesByDir, { indent: 2 }))
+
   // Group files by their discovered config
   // { '.lintstagedrc.json': { config: {...}, files: [...] } }
   const configGroups = {}
 
+  debugLog('Discovering config files...')
+
   await Promise.all(
     Object.entries(filesByDir).map(([dir, files]) => {
       // Discover config from the base directory of the file
       return loadConfig({ cwd: dir }, logger).then(({ config, filepath }) => {
-        if (!config) return
+        if (!config) {
+          debugLog('Found no config from "%s"!', dir)
+          return
+        }
 
         if (filepath in configGroups) {
+          debugLog('Found existing config "%s" from "%s"!', filepath, dir)
           // Re-use cached config and skip validation
           configGroups[filepath].files.push(...files)
           return
         }
 
+        debugLog('Found new config "%s" from "%s"!', filepath, dir)
+
         const validatedConfig = validateConfig(config, filepath, logger)
         configGroups[filepath] = { config: validatedConfig, files }
       })
@@ -72,9 +95,12 @@ export const getConfigGroups = async ({ configObject, configPath, files }, logge
 
   // Throw if no configurations were found
   if (Object.keys(configGroups).length === 0) {
+    debugLog('Found no config groups!')
     logger.error(`${ConfigNotFoundError.message}.`)
     throw ConfigNotFoundError
   }
 
+  debugLog('Grouped staged files into %d groups!', Object.keys(configGroups).length)
+
   return configGroups
 }