pkg/plugins: make package-level socketsPath var a LocalRegistry field

This variable was only accessed from within LocalRegistry methods, but
due to being a package-level variable, tests had to deal with setting
and resetting it.

Move it to be a field scoped to the LocalRegistry. This simplifies the
tests, and to make this more transparent, also removing the "Setup()"
helper (which, wasn't marked as a t.Helper()).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/plugins/discovery.go

@@ -13,34 +13,35 @@ import (
 	"github.com/pkg/errors"
 )
 
-var (
-	// ErrNotFound plugin not found
-	ErrNotFound = errors.New("plugin not found")
-	socketsPath = "/run/docker/plugins"
-)
+// ErrNotFound plugin not found
+var ErrNotFound = errors.New("plugin not found")
+
+const defaultSocketsPath = "/run/docker/plugins"
 
 // LocalRegistry defines a registry that is local (using unix socket).
 type LocalRegistry struct {
-	specsPaths []string
+	socketsPath string
+	specsPaths  []string
 }
 
 func NewLocalRegistry() LocalRegistry {
 	return LocalRegistry{
-		specsPaths: specsPaths(),
+		socketsPath: defaultSocketsPath,
+		specsPaths:  specsPaths(),
 	}
 }
 
 // Scan scans all the plugin paths and returns all the names it found
 func (l *LocalRegistry) Scan() ([]string, error) {
 	var names []string
-	dirEntries, err := os.ReadDir(socketsPath)
+	dirEntries, err := os.ReadDir(l.socketsPath)
 	if err != nil && !os.IsNotExist(err) {
 		return nil, errors.Wrap(err, "error reading dir entries")
 	}
 
 	for _, entry := range dirEntries {
 		if entry.IsDir() {
-			fi, err := os.Stat(filepath.Join(socketsPath, entry.Name(), entry.Name()+".sock"))
+			fi, err := os.Stat(filepath.Join(l.socketsPath, entry.Name(), entry.Name()+".sock"))
 			if err != nil {
 				continue
 			}
@@ -87,7 +88,7 @@ func (l *LocalRegistry) Scan() ([]string, error) {
 
 // Plugin returns the plugin registered with the given name (or returns an error).
 func (l *LocalRegistry) Plugin(name string) (*Plugin, error) {
-	socketPaths := pluginPaths(socketsPath, name, ".sock")
+	socketPaths := pluginPaths(l.socketsPath, name, ".sock")
 	for _, p := range socketPaths {
 		if fi, err := os.Stat(p); err == nil && fi.Mode()&os.ModeSocket != 0 {
 			return NewLocalPlugin(name, "unix://"+p), nil

pkg/plugins/discovery_test.go

@@ -6,23 +6,12 @@ import (
 	"testing"
 )
 
-func Setup(t *testing.T) (string, func(), LocalRegistry) {
-	tmpdir, err := os.MkdirTemp("", "docker-test")
-	if err != nil {
-		t.Fatal(err)
-	}
-	backup := socketsPath
-	socketsPath = tmpdir
-
-	return tmpdir, func() {
-		socketsPath = backup
-		os.RemoveAll(tmpdir)
-	}, LocalRegistry{specsPaths: []string{tmpdir}}
-}
-
 func TestFileSpecPlugin(t *testing.T) {
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	cases := []struct {
 		path string
@@ -70,8 +59,11 @@ func TestFileSpecPlugin(t *testing.T) {
 }
 
 func TestFileJSONSpecPlugin(t *testing.T) {
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	p := filepath.Join(tmpdir, "example.json")
 	spec := `{
@@ -115,8 +107,11 @@ func TestFileJSONSpecPlugin(t *testing.T) {
 }
 
 func TestFileJSONSpecPluginWithoutTLSConfig(t *testing.T) {
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	p := filepath.Join(tmpdir, "example.json")
 	spec := `{

pkg/plugins/discovery_unix_test.go

@@ -15,8 +15,11 @@ import (
 
 func TestLocalSocket(t *testing.T) {
 	// TODO Windows: Enable a similar version for Windows named pipes
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	cases := []string{
 		filepath.Join(tmpdir, "echo.sock"),
@@ -62,8 +65,11 @@ func TestLocalSocket(t *testing.T) {
 }
 
 func TestScan(t *testing.T) {
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	pluginNames, err := r.Scan()
 	if err != nil {
@@ -103,8 +109,11 @@ func TestScan(t *testing.T) {
 }
 
 func TestScanNotPlugins(t *testing.T) {
-	tmpdir, unregister, localRegistry := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	localRegistry := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	// not that `Setup()` above sets the sockets path and spec path dirs, which
 	// `Scan()` uses to find plugins to the returned `tmpdir`

pkg/plugins/plugin_test.go

@@ -127,8 +127,11 @@ func TestPluginWithNoManifest(t *testing.T) {
 
 func TestGetAll(t *testing.T) {
 	t.Parallel()
-	tmpdir, unregister, r := Setup(t)
-	defer unregister()
+	tmpdir := t.TempDir()
+	r := LocalRegistry{
+		socketsPath: tmpdir,
+		specsPaths:  []string{tmpdir},
+	}
 
 	p := filepath.Join(tmpdir, "example.json")
 	spec := `{