From e4dc7dc2a60f12de267453ef420b7e00f66ff76f Mon Sep 17 00:00:00 2001
From: Chris Olszewski <chris.olszewski@vercel.com>
Date: Fri, 19 May 2023 09:44:56 -0700
Subject: [PATCH] feat(prune) allow pruning of projects using Yarn PnP  (#5019)

### Description

We have had Yarn2+ support* for quite awhile now. This PR is one of the
final steps to remove that asterisks and allow Yarn PnP to be used.

A note is that we currently don't copy over the `.pnp.cjs` file or the
`.yarn/cache` which are required for [zero
installs](https://yarnpkg.com/features/zero-installs). We skip this a
naive copy would cause Docker cache misses in the same way a naive copy
of the lockfile would. Future work can include correctly pruning this
file and directory to allow for the `yarn install` on a cache miss to be
even faster.

### Testing Instructions

Manual testing that `yarn install --immutable` works for PnP projects.

Added an integration test that verifies we no longer throw when trying
to prune a PnP project and that we don't copy over files that would bust
the cache.

---------

Co-authored-by: Chris Olszewski <Chris Olszewski>
---
 cli/internal/packagemanager/berry.go          |  7 -----
 .../packagemanager/packagemanager_test.go     |  2 +-
 cli/internal/util/backends.go                 | 30 -------------------
 .../integration/tests/prune/yarn-pnp.t        | 15 ++++++++++
 4 files changed, 16 insertions(+), 38 deletions(-)
 delete mode 100644 cli/internal/util/backends.go
 create mode 100644 turborepo-tests/integration/tests/prune/yarn-pnp.t

diff --git a/cli/internal/packagemanager/berry.go b/cli/internal/packagemanager/berry.go
index b1964468f2f04..2bcb12c8ea062 100644
--- a/cli/internal/packagemanager/berry.go
+++ b/cli/internal/packagemanager/berry.go
@@ -4,11 +4,9 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/pkg/errors"
 	"github.com/vercel/turbo/cli/internal/fs"
 	"github.com/vercel/turbo/cli/internal/lockfile"
 	"github.com/vercel/turbo/cli/internal/turbopath"
-	"github.com/vercel/turbo/cli/internal/util"
 )
 
 var nodejsBerry = PackageManager{
@@ -41,11 +39,6 @@ var nodejsBerry = PackageManager{
 	},
 
 	canPrune: func(cwd turbopath.AbsoluteSystemPath) (bool, error) {
-		if isNMLinker, err := util.IsNMLinker(cwd.ToStringDuringMigration()); err != nil {
-			return false, errors.Wrap(err, "could not determine if yarn is using `nodeLinker: node-modules`")
-		} else if !isNMLinker {
-			return false, errors.New("only yarn v2/v3 with `nodeLinker: node-modules` is supported at this time")
-		}
 		return true, nil
 	},
 
diff --git a/cli/internal/packagemanager/packagemanager_test.go b/cli/internal/packagemanager/packagemanager_test.go
index 012094215b26f..ef79b6d8e12f8 100644
--- a/cli/internal/packagemanager/packagemanager_test.go
+++ b/cli/internal/packagemanager/packagemanager_test.go
@@ -175,7 +175,7 @@ func Test_CanPrune(t *testing.T) {
 	assert.NilError(t, err, "GetCwd")
 	wants := map[string]want{
 		"nodejs-npm":   {true, false},
-		"nodejs-berry": {false, true},
+		"nodejs-berry": {true, false},
 		"nodejs-yarn":  {true, false},
 		"nodejs-pnpm":  {true, false},
 		"nodejs-pnpm6": {true, false},
diff --git a/cli/internal/util/backends.go b/cli/internal/util/backends.go
deleted file mode 100644
index 66941ad71839e..0000000000000
--- a/cli/internal/util/backends.go
+++ /dev/null
@@ -1,30 +0,0 @@
-package util
-
-import (
-	"fmt"
-	"io/ioutil"
-	"path/filepath"
-
-	"github.com/vercel/turbo/cli/internal/yaml"
-)
-
-// YarnRC Represents contents of .yarnrc.yml
-type YarnRC struct {
-	NodeLinker string `yaml:"nodeLinker"`
-}
-
-// IsNMLinker Checks that Yarn is set to use the node-modules linker style
-func IsNMLinker(cwd string) (bool, error) {
-	yarnRC := &YarnRC{}
-
-	bytes, err := ioutil.ReadFile(filepath.Join(cwd, ".yarnrc.yml"))
-	if err != nil {
-		return false, fmt.Errorf(".yarnrc.yml: %w", err)
-	}
-
-	if yaml.Unmarshal(bytes, yarnRC) != nil {
-		return false, fmt.Errorf(".yarnrc.yml: %w", err)
-	}
-
-	return yarnRC.NodeLinker == "node-modules", nil
-}
diff --git a/turborepo-tests/integration/tests/prune/yarn-pnp.t b/turborepo-tests/integration/tests/prune/yarn-pnp.t
new file mode 100644
index 0000000000000..ef677ae2f5933
--- /dev/null
+++ b/turborepo-tests/integration/tests/prune/yarn-pnp.t
@@ -0,0 +1,15 @@
+Setup
+  $ . ${TESTDIR}/../../../helpers/setup.sh
+  $ . ${TESTDIR}/../_helpers/copy_fixture.sh $(pwd) berry_resolutions
+Remove linker override
+  $ rm .yarnrc.yml
+Prune the project
+  $ ${TURBO} prune --scope=a
+  Generating pruned monorepo for a in .*out (re)
+   - Added a
+
+Verify that .pnp.cjs isn't coppied causing unnecessary cache misses
+  $ ls -A out/
+  package.json
+  packages
+  yarn.lock