feat: expect-patch flag

Author: escaton

README.md

@@ -229,6 +229,10 @@ Run `patch-package` without arguments to apply all patches in your project.
 
   Specify the name for the directory in which the patch files are located
 
+- `--expect-patch`
+
+  Prints error when no patches happen. Best combined with `--error-on-fail` (enabled by default on CI).
+
 #### Notes
 
 To apply patches individually, you may use `git`:

src/applyPatches.ts

@@ -95,28 +95,34 @@ export function applyPatchesForApp({
   appPath,
   reverse,
   patchDir,
+  expectPatch,
   shouldExitWithError,
   shouldExitWithWarning,
   bestEffort,
 }: {
   appPath: string
   reverse: boolean
   patchDir: string
+  expectPatch: boolean
   shouldExitWithError: boolean
   shouldExitWithWarning: boolean
   bestEffort: boolean
 }): void {
   const patchesDirectory = join(appPath, patchDir)
   const groupedPatches = getGroupedPatches(patchesDirectory)
 
-  if (groupedPatches.numPatchFiles === 0) {
-    console.log(chalk.blueBright("No patch files found"))
-    return
-  }
-
   const errors: string[] = []
   const warnings: string[] = [...groupedPatches.warnings]
 
+  if (groupedPatches.numPatchFiles === 0) {
+    if (expectPatch) {
+      errors.push("No patch files found")
+    } else {
+      console.log(chalk.blueBright("No patch files found"))
+      return
+    }
+  }
+
   for (const patches of Object.values(
     groupedPatches.pathSpecifierToPatchFiles,
   )) {

src/index.ts

@@ -25,6 +25,7 @@ const argv = minimist(process.argv.slice(2), {
     "error-on-warn",
     "create-issue",
     "partial",
+    "expect-patch",
     "",
   ],
   string: ["patch-dir", "append", "rebase"],
@@ -114,11 +115,13 @@ if (argv.version || argv.v) {
       process.env.NODE_ENV === "test"
 
     const shouldExitWithWarning = !!argv["error-on-warn"]
+    const expectPatch = !!argv["expect-patch"]
 
     applyPatchesForApp({
       appPath,
       reverse,
       patchDir,
+      expectPatch,
       shouldExitWithError,
       shouldExitWithWarning,
       bestEffort: argv.partial,
@@ -177,6 +180,15 @@ Usage:
       This option was added to help people using CircleCI avoid an issue around caching
       and patch file updates (https://github.com/ds300/patch-package/issues/37),
       but might be useful in other contexts too.
+    
+    ${chalk.bold("--expect-patch")}
+        
+      Prints an error if no patch files were found.
+
+      This option works in tandem with ${chalk.bold(
+        "--error-on-fail",
+      )} (enabled by default in CI) to prevent
+      accidental skips due to patch folder was missed or ignored. For example during COPY in Dockerfile, or in .dockerignore.
       
 
   2. Creating patch files