Fail when patch found for uninstalled package

integration-tests/fails-when-no-package/__snapshots__/fails-when-no-package.test.ts.snap

@@ -0,0 +1,8 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Test fails-when-no-package: no package present failure 1`] = `
+"SNAPSHOT: no package present failure
+Error: Patch file found for package left-pad which is not present at node_modules/left-pad
+error Command failed with exit code 1.
+END SNAPSHOT"
+`;

integration-tests/fails-when-no-package/fails-when-no-package.sh

@@ -0,0 +1,11 @@
+# make sure errors stop the script
+set -e
+
+echo "add patch-package"
+yarn add $1
+
+(>&2 echo "SNAPSHOT: no package present failure")
+if yarn patch-package; then
+  exit 1
+fi
+(>&2 echo "END SNAPSHOT")

integration-tests/fails-when-no-package/fails-when-no-package.test.ts

@@ -0,0 +1,5 @@
+import { runIntegrationTest } from "../runIntegrationTest"
+runIntegrationTest({
+  projectName: "fails-when-no-package",
+  shouldProduceSnapshots: true,
+})

integration-tests/fails-when-no-package/package.json

@@ -0,0 +1,9 @@
+{
+  "name": "fails-when-no-package",
+  "version": "1.0.0",
+  "description": "integration test for patch-package",
+  "main": "index.js",
+  "author": "",
+  "license": "ISC",
+  "dependencies": {}
+}

integration-tests/fails-when-no-package/patches/left-pad+1.1.3.patch

@@ -0,0 +1,13 @@
+diff --git a/node_modules/left-pad/index.js b/node_modules/left-pad/index.js
+index 26f73ff..60f3f56 100644
+--- a/node_modules/left-pad/index.js
++++ b/node_modules/left-pad/index.js
+@@ -4,7 +4,7 @@
+      * To Public License, Version 2, as published by Sam Hocevar. See
+      * http://www.wtfpl.net/ for more details. */
+ 'use strict';
+-module.exports = leftPad;
++module.exports = patch-package;
+
+ var cache = [
+   '',

integration-tests/fails-when-no-package/yarn.lock

@@ -0,0 +1,4 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+

integration-tests/patches/left-pad+1.1.3.patch

@@ -0,0 +1,13 @@
+diff --git a/node_modules/left-pad/index.js b/node_modules/left-pad/index.js
+index 26f73ff..60f3f56 100644
+--- a/node_modules/left-pad/index.js
++++ b/node_modules/left-pad/index.js
+@@ -4,7 +4,7 @@
+      * To Public License, Version 2, as published by Sam Hocevar. See
+      * http://www.wtfpl.net/ for more details. */
+ 'use strict';
+-module.exports = leftPad;
++module.exports = patch-package;
+
+ var cache = [
+   '',

src/applyPatches.ts

@@ -2,7 +2,7 @@ import chalk from "chalk"
 import { getPatchFiles } from "./patchFs"
 import { executeEffects } from "./patch/apply"
 import { existsSync } from "fs-extra"
-import { join, resolve } from "./path"
+import { join, resolve, relative } from "./path"
 import { posix } from "path"
 import {
   getPackageDetailsFromPatchFilename,
@@ -17,6 +17,8 @@ import { readPatch } from "./patch/read"
 // see https://github.com/ds300/patch-package/issues/86
 const shouldExitPostinstallWithError = isCi || process.env.NODE_ENV === "test"
 
+const exit = () => process.exit(shouldExitPostinstallWithError ? 1 : 0)
+
 function findPatchFiles(patchesDirectory: string): string[] {
   if (!existsSync(patchesDirectory)) {
     return []
@@ -33,22 +35,35 @@ function getInstalledPackageVersion({
   appPath: string
   path: string
   pathSpecifier: string
-}): string | null {
+}): string {
   const packageDir = join(appPath, path)
   if (!existsSync(packageDir)) {
-    console.log(
-      `${chalk.yellow(
-        "Warning:",
-      )} Patch file found for package ${posix.basename(pathSpecifier)}` +
-        ` which is not present at ${packageDir}`,
+    console.error(
+      `${chalk.red("Error:")} Patch file found for package ${posix.basename(
+        pathSpecifier,
+      )}` + ` which is not present at ${relative(".", packageDir)}`,
     )
 
-    return null
+    exit()
   }
 
   const { version } = require(join(packageDir, "package.json"))
   // normalize version for `npm ci`
-  return semver.valid(version)
+  const result = semver.valid(version)
+  if (result === null) {
+    console.error(
+      `${chalk.red(
+        "Error:",
+      )} Version string '${version}' cannot be parsed from ${join(
+        packageDir,
+        "package.json",
+      )}`,
+    )
+
+    exit()
+  }
+
+  return result as string
 }
 
 export function applyPatchesForApp({
@@ -84,10 +99,6 @@ export function applyPatchesForApp({
       pathSpecifier,
     })
 
-    if (!installedPackageVersion) {
-      return
-    }
-
     if (
       applyPatch({
         patchFilePath: resolve(patchesDirectory, filename) as string,
@@ -131,7 +142,8 @@ export function applyPatchesForApp({
           pathSpecifier,
         })
       }
-      process.exit(shouldExitPostinstallWithError ? 1 : 0)
+
+      exit()
     }
   })
 }