From 56dbb6b4c295d9b76f557779af14f5d21f6cf1d0 Mon Sep 17 00:00:00 2001
From: Luke Karrys <luke@lukekarrys.com>
Date: Thu, 2 May 2024 12:27:59 -0700
Subject: [PATCH] fix: properly check for diff with multiple files from
 overwrite:false

Fixes #437
---
 lib/check/check-apply.js      |  2 +-
 lib/util/files.js             | 23 ++++++++++++++++-------
 lib/util/parser.js            |  9 +++++++++
 test/apply/overwrite-false.js | 21 +++++++++++++++++++++
 4 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/lib/check/check-apply.js b/lib/check/check-apply.js
index b1cde376..2f47946a 100644
--- a/lib/check/check-apply.js
+++ b/lib/check/check-apply.js
@@ -12,7 +12,7 @@ const run = async (type, dir, files, options) => {
   const { add: addFiles, rm: rmFiles } = files
 
   const rm = await rmEach(dir, rmFiles, options, (f) => rel(f))
-  const parseOpts = { allowMultipleSources: false }
+  const parseOpts = { command: 'check' }
   const [add, update] = partition(await parseEach(dir, addFiles, options, parseOpts, async (p) => {
     const diff = await p.applyDiff()
     const target = rel(p.target)
diff --git a/lib/util/files.js b/lib/util/files.js
index 713c01e0..ad52f31e 100644
--- a/lib/util/files.js
+++ b/lib/util/files.js
@@ -31,7 +31,7 @@ const mergeFiles = mergeWithCustomizers((value, srcValue, key, target, source, s
   }
 }, customizers.overwriteArrays)
 
-const fileEntries = (dir, files, options, { allowMultipleSources = true } = {}) => {
+const fileEntries = (dir, files, options, { command } = {}) => {
   const results = []
 
   for (const [key, source] of Object.entries(files)) {
@@ -45,12 +45,21 @@ const fileEntries = (dir, files, options, { allowMultipleSources = true } = {})
 
     if (Array.isArray(source)) {
       // When turning an object of files into all its entries, we allow
-      // multiples when applying changes, but not when checking for changes
-      // since earlier files would always return as needing an update. So we
-      // either allow multiples and return the array or only return the last
-      // source file in the array.
-      const sources = allowMultipleSources ? source : source.slice(-1)
-      results.push(...sources.map(s => [target, s]))
+      // multiples when applying and checking changes. When applying we can
+      // run them each as [[t,s1],[t,s2],...] because they can be applied in order
+      // and get the correct result. When checking for changes we need to run them
+      // as [target,{file:[s1,s2...]}] so that all files can be merged first and then
+      // we can diff our target against that.
+      if (command === 'check') {
+        const sources = source.reduce((acc, { file, ...rest }) => {
+          acc.file.push(file)
+          Object.assign(acc, rest)
+          return acc
+        }, { file: [] })
+        results.push([target, sources])
+      } else {
+        results.push(...source.map(s => [target, s]))
+      }
     } else {
       results.push([target, source])
     }
diff --git a/lib/util/parser.js b/lib/util/parser.js
index 27f498b7..48b5f4e8 100644
--- a/lib/util/parser.js
+++ b/lib/util/parser.js
@@ -62,10 +62,16 @@ class Base {
   }
 
   read (s) {
+    if (Array.isArray(s)) {
+      return Promise.all(s.map(f => this.read(f)))
+    }
     return fs.readFile(s, { encoding: 'utf-8' })
   }
 
   template (s) {
+    if (Array.isArray(s)) {
+      return Promise.all(s.map(f => this.template(f)))
+    }
     return template(s, this.options)
   }
 
@@ -285,6 +291,9 @@ class Json extends Base {
   }
 
   parse (s) {
+    if (Array.isArray(s)) {
+      return s.map(f => this.parse(f)).reduce((a, f) => this.merge(a, f), {})
+    }
     return jsonParse(s)
   }
 
diff --git a/test/apply/overwrite-false.js b/test/apply/overwrite-false.js
index ca0bedbd..260d7f7f 100644
--- a/test/apply/overwrite-false.js
+++ b/test/apply/overwrite-false.js
@@ -31,10 +31,31 @@ t.test('json merge', async (t) => {
   })
 
   await s.apply()
+  t.strictSame(await s.check(), [])
 
   const pkg = await s.readJson('package.json')
   t.equal(pkg.scripts.test, 'tap test/')
   t.equal(pkg.scripts.snap, 'tap')
 
+  await s.writeJson('package.json', {
+    ...pkg,
+    author: 'What?',
+    scripts: {
+      ...pkg.scripts,
+      test: 'tap',
+    },
+    templateOSS: {
+      ...pkg.templateOSS,
+      version: '1.0.0',
+    },
+  })
+
+  const checks = await s.check()
+  t.equal(checks.length, 1)
+  t.match(checks[0].title, 'package.json needs to be updated')
+  t.match(checks[0].body[0], `"author" is "What?", expected "GitHub Inc."`)
+  t.match(checks[0].body[0], `scripts.test" is "tap", expected "tap test/"`)
+
+  await s.apply()
   t.strictSame(await s.check(), [])
 })