fix: evaluate functional configuration only once

lib/makeCmdTasks.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const resolveTaskFn = require('./resolveTaskFn')
+const { createError } = require('./validateConfig')
 
 const debug = require('debug')('lint-staged:make-cmd-tasks')
 
@@ -15,32 +16,34 @@ const debug = require('debug')('lint-staged:make-cmd-tasks')
  */
 module.exports = async function makeCmdTasks({ commands, files, gitDir, shell }) {
   debug('Creating listr tasks for commands %o', commands)
-  const commandsArray = Array.isArray(commands) ? commands : [commands]
+  const commandArray = Array.isArray(commands) ? commands : [commands]
   const cmdTasks = []
 
-  for (const cmd of commandsArray) {
+  for (const cmd of commandArray) {
     // command function may return array of commands that already include `stagedFiles`
     const isFn = typeof cmd === 'function'
     const resolved = isFn ? await cmd(files) : cmd
 
     const resolvedArray = Array.isArray(resolved) ? resolved : [resolved] // Wrap non-array command as array
 
-    // Function command should not be used as the task title as-is
-    // because the resolved string it might be very long
-    // Create a matching command array with [file] in place of file names
-    let mockCmdTasks
-    if (isFn) {
-      const mockFileList = Array(files.length).fill('[file]')
-      const resolved = await cmd(mockFileList)
-      mockCmdTasks = Array.isArray(resolved) ? resolved : [resolved]
-    }
-
-    for (const [i, command] of resolvedArray.entries()) {
+    for (const command of resolvedArray) {
       let title = isFn ? '[Function]' : command
-      if (isFn && mockCmdTasks[i]) {
-        // If command is a function, use the matching mock command as title,
-        // but since might include multiple [file] arguments, shorten to one
-        title = mockCmdTasks[i].replace(/\[file\].*\[file\]/, '[file]')
+
+      if (isFn) {
+        // If the function linter didn't return string | string[]  it won't work
+        // Do the validation here instead of `validateConfig` to skip evaluating the function multiple times
+        if (typeof command !== 'string') {
+          throw new Error(
+            createError(
+              title,
+              'Function task should return a string or an array of strings',
+              resolved
+            )
+          )
+        }
+
+        const [startOfFn] = command.split(' ')
+        title += ` ${startOfFn} ...` // Append function name, like `[Function] eslint ...`
       }
 
       cmdTasks.push({

lib/validateConfig.js

@@ -80,21 +80,6 @@ module.exports = function validateConfig(config) {
           )
         )
       }
-
-      entries.forEach(([, task]) => {
-        if (typeof task !== 'function') return
-        const resolved = task(['[filename]'])
-        if (typeof resolved === 'string') return
-        if (!Array.isArray(resolved) || resolved.some(subtask => typeof subtask !== 'string')) {
-          errors.push(
-            createError(
-              task,
-              'Function task should return a string or an array of strings',
-              resolved
-            )
-          )
-        }
-      })
     })
   }
 
@@ -104,3 +89,5 @@ module.exports = function validateConfig(config) {
 
   return config
 }
+
+module.exports.createError = createError

test/__snapshots__/validateConfig.spec.js.snap

@@ -150,15 +150,3 @@ Please refer to https://github.com/okonet/lint-staged#configuration for more inf
 `;
 
 exports[`validateConfig should throw when detecting deprecated advanced configuration 2`] = `""`;
-
-exports[`validateConfig should throw when function task returns incorrect values 1`] = `
-"● Validation Error:
-
-  Invalid value for 'filenames => filenames.map(file => [\`eslint --fix \${file}\`, \`git add \${file}\`])'.
-
-  Function task should return a string or an array of strings.
- 
-  Configured value is: [['eslint --fix [filename]', 'git add [filename]']]
-
-Please refer to https://github.com/okonet/lint-staged#configuration for more information..."
-`;

test/makeCmdTasks.spec.js

@@ -61,7 +61,7 @@ describe('makeCmdTasks', () => {
   it('should work with function task returning a string', async () => {
     const res = await makeCmdTasks({ commands: () => 'test', gitDir, files: ['test.js'] })
     expect(res.length).toBe(1)
-    expect(res[0].title).toEqual('test')
+    expect(res[0].title).toEqual('[Function] test ...')
   })
 
   it('should work with function task returning array of string', async () => {
@@ -71,8 +71,8 @@ describe('makeCmdTasks', () => {
       files: ['test.js']
     })
     expect(res.length).toBe(2)
-    expect(res[0].title).toEqual('test')
-    expect(res[1].title).toEqual('test2')
+    expect(res[0].title).toEqual('[Function] test ...')
+    expect(res[1].title).toEqual('[Function] test2 ...')
   })
 
   it('should work with function task accepting arguments', async () => {
@@ -82,8 +82,8 @@ describe('makeCmdTasks', () => {
       files: ['test.js', 'test2.js']
     })
     expect(res.length).toBe(2)
-    expect(res[0].title).toEqual('test [file]')
-    expect(res[1].title).toEqual('test [file]')
+    expect(res[0].title).toEqual('[Function] test ...')
+    expect(res[1].title).toEqual('[Function] test ...')
   })
 
   it('should work with array of mixed string and function tasks', async () => {
@@ -93,26 +93,31 @@ describe('makeCmdTasks', () => {
       files: ['test.js', 'test2.js', 'test3.js']
     })
     expect(res.length).toBe(5)
-    expect(res[0].title).toEqual('test')
+    expect(res[0].title).toEqual('[Function] test ...')
     expect(res[1].title).toEqual('test2')
-    expect(res[2].title).toEqual('test [file]')
-    expect(res[3].title).toEqual('test [file]')
-    expect(res[4].title).toEqual('test [file]')
-  })
-
-  it('should generate short names for function tasks with long file list', async () => {
-    const res = await makeCmdTasks({
-      commands: filenames => `test ${filenames.map(file => `--file ${file}`).join(' ')}`,
-      gitDir,
-      files: Array(100).fill('file.js') // 100 times `file.js`
-    })
-    expect(res.length).toBe(1)
-    expect(res[0].title).toEqual('test --file [file]')
+    expect(res[2].title).toEqual('[Function] test ...')
+    expect(res[3].title).toEqual('[Function] test ...')
+    expect(res[4].title).toEqual('[Function] test ...')
   })
 
   it('should work with async function tasks', async () => {
     const res = await makeCmdTasks({ commands: async () => 'test', gitDir, files: ['test.js'] })
     expect(res.length).toBe(1)
-    expect(res[0].title).toEqual('test')
+    expect(res[0].title).toEqual('[Function] test ...')
+  })
+
+  it("should throw when function task doesn't return string | string[]", async () => {
+    await expect(makeCmdTasks({ commands: () => null, gitDir, files: ['test.js'] })).rejects
+      .toThrowErrorMatchingInlineSnapshot(`
+"● Validation Error:
+
+  Invalid value for '[Function]'.
+
+  Function task should return a string or an array of strings.
+ 
+  Configured value is: null
+
+Please refer to https://github.com/okonet/lint-staged#configuration for more information..."
+`)
   })
 })

test/runAll.unmocked.spec.js

@@ -710,8 +710,8 @@ describe('runAll', () => {
       LOG Preparing... [completed]
       LOG Running tasks... [started]
       LOG Running tasks for *.js [started]
-      LOG git stash drop [started]
-      LOG git stash drop [completed]
+      LOG [Function] git ... [started]
+      LOG [Function] git ... [completed]
       LOG Running tasks for *.js [completed]
       LOG Running tasks... [completed]
       LOG Applying modifications... [started]

test/validateConfig.spec.js

@@ -49,13 +49,6 @@ describe('validateConfig', () => {
     expect(console.printHistory()).toMatchSnapshot()
   })
 
-  it('should throw when function task returns incorrect values', () => {
-    const invalidConfig = {
-      '*.js': filenames => filenames.map(file => [`eslint --fix ${file}`, `git add ${file}`])
-    }
-    expect(() => validateConfig(invalidConfig)).toThrowErrorMatchingSnapshot()
-  })
-
   it('should throw when detecting deprecated advanced configuration', () => {
     const advancedConfig = {
       chunkSize: 10,