From 86bc7752a75f657656b5eda70180322441aca105 Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Wed, 24 Aug 2022 10:35:02 +0200
Subject: [PATCH] feat: add `COREPACK_ENABLE_STRICT` env variable

---
 README.md            | 10 ++++++++--
 sources/specUtils.ts |  2 ++
 tests/main.test.ts   | 28 ++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 36e5d1028..8ba03a760 100644
--- a/README.md
+++ b/README.md
@@ -111,12 +111,18 @@ This command will retrieve the given package manager from the specified archive
 
 ## Environment Variables
 
-- `COREPACK_ENABLE_NETWORK` can be set to `0` to prevent Corepack from accessing the network (in which case you'll be responsible for hydrating the package manager versions that will be required for the projects you'll run, using `corepack hydrate`).
-
 - `COREPACK_DEFAULT_TO_LATEST` can be set to `0` in order to instruct Corepack
   not to lookup on the remote registry for the latest version of the selected
   package manager.
 
+- `COREPACK_ENABLE_NETWORK` can be set to `0` to prevent Corepack from accessing
+  the network (in which case you'll be responsible for hydrating the package
+  manager versions that will be required for the projects you'll run, using
+  `corepack hydrate`).
+
+- `COREPACK_ENABLE_STRICT` can be set to `0` to prevent Corepack from checking
+  if the package manager corresponds to the one defined for the current project.
+
 - `COREPACK_HOME` can be set in order to define where Corepack should install
   the package managers. By default it is set to `%LOCALAPPDATA%\node\corepack`
   on Windows, and to `$HOME/.cache/node/corepack` everywhere else.
diff --git a/sources/specUtils.ts b/sources/specUtils.ts
index e69bc8fe3..f587d3276 100644
--- a/sources/specUtils.ts
+++ b/sources/specUtils.ts
@@ -44,6 +44,8 @@ export async function findProjectSpec(initialCwd: string, locator: Locator, {tra
   // A locator is a valid descriptor (but not the other way around)
   const fallbackLocator = {name: locator.name, range: locator.reference};
 
+  if (process.env.COREPACK_ENABLE_STRICT === `0`) return fallbackLocator;
+
   while (true) {
     const result = await loadSpec(initialCwd);
 
diff --git a/tests/main.test.ts b/tests/main.test.ts
index 2d93a013b..05d414ce7 100644
--- a/tests/main.test.ts
+++ b/tests/main.test.ts
@@ -219,6 +219,34 @@ it(`should allow to call "prepare" without arguments within a configured project
   });
 });
 
+it(`should refuse to run a different package manager within a configured project`, async () => {
+  await xfs.mktempPromise(async cwd => {
+    await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+      packageManager: `yarn@1.0.0`,
+    });
+
+    process.env.FORCE_COLOR = `0`;
+
+    await expect(runCli(cwd, [`pnpm`, `--version`])).resolves.toMatchObject({
+      stdout: `Usage Error: This project is configured to use yarn\n\n$ pnpm ...\n`,
+      exitCode: 1,
+    });
+
+    // Disable strict checking to workaround the UsageError.
+    process.env.COREPACK_ENABLE_STRICT = `0`;
+
+    try {
+      await expect(runCli(cwd, [`pnpm`, `--version`])).resolves.toMatchObject({
+        stdout: `${config.definitions.pnpm.default.split(`+`, 1)[0]}\n`,
+        exitCode: 0,
+      });
+    } finally {
+      delete process.env.COREPACK_ENABLE_STRICT;
+      delete process.env.FORCE_COLOR;
+    }
+  });
+});
+
 it(`should allow to call "prepare" with --all to prepare all package managers`, async () => {
   await xfs.mktempPromise(async cwd => {
     await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {