From cbdb82c950f0e746565bf765a494d0a73522ff91 Mon Sep 17 00:00:00 2001
From: Othmane KINANE <15254824+OKinane@users.noreply.github.com>
Date: Mon, 8 Nov 2021 18:17:42 +0100
Subject: [PATCH] fix: support --cache-strategy ESLint argument (fixes #29926)
 (#29928)

* fix: support --cache-strategy ESLint argument

* add integration tests for --cache-strategy

* fix: add cacheStrategy to eslintOptions

* minor adjustments in next lint help message for --cache-strategy

Co-authored-by: Steven <steven@ceriously.com>
---
 packages/next/cli/next-lint.ts             |  3 ++
 test/integration/eslint/test/index.test.js | 41 ++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/packages/next/cli/next-lint.ts b/packages/next/cli/next-lint.ts
index 9f2be2e96abb0b..a225753a8174f5 100755
--- a/packages/next/cli/next-lint.ts
+++ b/packages/next/cli/next-lint.ts
@@ -30,6 +30,7 @@ const eslintOptions = (args: arg.Spec, defaultCacheLocation: string) => ({
     args['--report-unused-disable-directives'] || null,
   cache: !Boolean(args['--no-cache']),
   cacheLocation: args['--cache-location'] || defaultCacheLocation,
+  cacheStrategy: args['--cache-strategy'] || 'metadata',
   errorOnUnmatchedPattern: args['--error-on-unmatched-pattern']
     ? Boolean(args['--error-on-unmatched-pattern'])
     : false,
@@ -67,6 +68,7 @@ const nextLint: cliCommand = async (argv) => {
     '--cache': Boolean, // Although cache is enabled by default, this dummy flag still exists to not cause any breaking changes
     '--no-cache': Boolean,
     '--cache-location': String,
+    '--cache-strategy': String,
     '--error-on-unmatched-pattern': Boolean,
     '--format': String,
 
@@ -134,6 +136,7 @@ const nextLint: cliCommand = async (argv) => {
         Caching:
           --no-cache                     Disable caching
           --cache-location path::String  Path to the cache file or directory - default: .eslintcache
+          --cache-strategy String        Strategy to use for detecting changed files in the cache, either metadata or content - default: metadata
         
         Miscellaneous:
           --error-on-unmatched-pattern   Show errors when any file patterns are unmatched - default: false
diff --git a/test/integration/eslint/test/index.test.js b/test/integration/eslint/test/index.test.js
index e9b499ab3d1942..ac7a005b48cbea 100644
--- a/test/integration/eslint/test/index.test.js
+++ b/test/integration/eslint/test/index.test.js
@@ -536,6 +536,47 @@ describe('ESLint', () => {
       expect(fs.existsSync(cacheFile)).toBe(true)
     })
 
+    const getEslintCacheContent = async (cacheDir) => {
+      const eslintCacheDir = join(cacheDir, 'eslint/')
+      let files = await fs.readdir(eslintCacheDir)
+      let cacheFiles = files.filter((f) => /\.cache/.test(f))
+      expect(cacheFiles.length).toBe(1)
+      const cacheFile = join(eslintCacheDir, cacheFiles[0])
+      return await fs.readFile(cacheFile, 'utf8')
+    }
+
+    test('the default eslint caching strategy is metadata', async () => {
+      const cacheDir = join(dirEslintCache, '.next', 'cache')
+
+      await fs.remove(cacheDir)
+      await nextLint(dirEslintCache)
+
+      const defaultStrategyCache = await getEslintCacheContent(cacheDir)
+
+      await fs.remove(cacheDir)
+      await nextLint(dirEslintCache, ['--cache-strategy', 'metadata'])
+
+      const metadataStrategyCache = await getEslintCacheContent(cacheDir)
+
+      expect(metadataStrategyCache).toBe(defaultStrategyCache)
+    })
+
+    test('cache with content strategy is different from the one with default strategy', async () => {
+      const cacheDir = join(dirEslintCache, '.next', 'cache')
+
+      await fs.remove(cacheDir)
+      await nextLint(dirEslintCache)
+
+      const defaultStrategyCache = await getEslintCacheContent(cacheDir)
+
+      await fs.remove(cacheDir)
+      await nextLint(dirEslintCache, ['--cache-strategy', 'content'])
+
+      const contentStrategyCache = await getEslintCacheContent(cacheDir)
+
+      expect(contentStrategyCache).not.toBe(defaultStrategyCache)
+    })
+
     test('file flag can selectively lint only a single file', async () => {
       const { stdout, stderr } = await nextLint(
         dirFileLinting,