Fixes findPackageLocator on parent directories (#2061)

* Fixes a bug in findPackageLocator

* Versions

.yarn/versions/83802125.yml

@@ -0,0 +1,24 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/plugin-pnp": patch
+  "@yarnpkg/pnp": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-node-modules"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/pnpify"

packages/acceptance-tests/pkg-tests-specs/sources/pnpapi.test.js

@@ -19,6 +19,15 @@ describe(`Plug'n'Play API`, () => {
   );
 
   describe(`std - v1`, () => {
+    test(
+      `it shouldn't report the project parent directory as being part of the project`,
+      makeTemporaryEnv({}, async ({path, run, source}) => {
+        await run(`install`);
+
+        await expect(source(`require('pnpapi').findPackageLocator('${npath.fromPortablePath(ppath.dirname(path))}/')`)).resolves.toEqual(null);
+      }),
+    );
+
     test(
       `it should expose resolveToUnqualified`,
       makeTemporaryEnv({}, async ({path, run, source}) => {

packages/yarnpkg-pnp/sources/loader/makeApi.ts

@@ -38,7 +38,7 @@ export function makeApi(runtimeState: RuntimeState, opts: MakeApiOptions): PnpAp
 
   // Matches if the path starts with a valid path qualifier (./, ../, /)
   // eslint-disable-next-line no-unused-vars
-  const isStrictRegExp = /^\.{0,2}\//;
+  const isStrictRegExp = /^(\/|\.{1,2}(\/|$))/;
 
   // Matches if the path must point to a directory (ie ends with /)
   const isDirRegExp = /\/$/;