Remove unused functions, variables, fields

opts/env_test: suppress a linter warning

this one:

> opts/env_test.go:95:4: U1000: field `err` is unused (unused)
> 			err      error
>			^

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

distribution/pull_v2_test.go

@@ -180,7 +180,7 @@ func TestValidateManifest(t *testing.T) {
 		t.Fatal("error unmarshaling manifest:", err)
 	}
 
-	verifiedManifest, err = verifySchema1Manifest(&badSignedManifest, expectedDigest)
+	_, err = verifySchema1Manifest(&badSignedManifest, expectedDigest)
 	if err == nil || !strings.HasPrefix(err.Error(), "image verification failed for digest") {
 		t.Fatal("expected validateManifest to fail with digest error")
 	}

layer/layer_test.go

@@ -171,10 +171,6 @@ func getCachedLayer(l Layer) *roLayer {
 	return l.(*roLayer)
 }
 
-func getMountLayer(l RWLayer) *mountedLayer {
-	return l.(*referencedRWLayer).mountedLayer
-}
-
 func createMetadata(layers ...Layer) []Metadata {
 	metadata := make([]Metadata, len(layers))
 	for i := range layers {

layer/mounted_layer.go

@@ -13,7 +13,6 @@ type mountedLayer struct {
 	mountID    string
 	initID     string
 	parent     *roLayer
-	path       string
 	layerStore *layerStore
 
 	sync.Mutex

opts/env_test.go

@@ -96,9 +96,9 @@ func TestValidateEnv(t *testing.T) {
 		}{
 			value:    "PaTh",
 			expected: fmt.Sprintf("PaTh=%v", os.Getenv("PATH")),
+			err:      nil,
 		}
 		testcase = append(testcase, tmp)
-
 	}
 
 	for _, r := range testcase {

pkg/mount/mount_unix_test.go

@@ -122,7 +122,7 @@ func TestMountReadonly(t *testing.T) {
 		}
 	}()
 
-	f, err = os.OpenFile(targetPath, os.O_RDWR, 0777)
+	_, err = os.OpenFile(targetPath, os.O_RDWR, 0777)
 	if err == nil {
 		t.Fatal("Should not be able to open a ro file as rw")
 	}

pkg/tailfile/tailfile.go

@@ -127,7 +127,6 @@ type scanner struct {
 	delim []byte
 	err   error
 	idx   int
-	done  bool
 }
 
 func (s *scanner) Start(ctx context.Context) int64 {

reference/store_test.go

@@ -110,8 +110,9 @@ func TestAddDeleteGet(t *testing.T) {
 		t.Fatalf("error creating temp file: %v", err)
 	}
 	_, err = jsonFile.Write([]byte(`{}`))
-	jsonFile.Close()
-	defer os.RemoveAll(jsonFile.Name())
+	assert.NilError(t, err)
+	_ = jsonFile.Close()
+	defer func() { _ = os.RemoveAll(jsonFile.Name()) }()
 
 	store, err := NewReferenceStore(jsonFile.Name())
 	if err != nil {

volume/service/service_test.go

@@ -147,14 +147,14 @@ func TestServiceGet(t *testing.T) {
 	assert.NilError(t, err)
 	assert.Assert(t, is.Len(v.Status, 1), v.Status)
 
-	v, err = service.Get(ctx, "test", opts.WithGetDriver("notarealdriver"))
+	_, err = service.Get(ctx, "test", opts.WithGetDriver("notarealdriver"))
 	assert.Assert(t, errdefs.IsConflict(err), err)
 	v, err = service.Get(ctx, "test", opts.WithGetDriver("d1"))
 	assert.Assert(t, err == nil)
 	assert.Assert(t, is.DeepEqual(created, v))
 
 	assert.Assert(t, ds.Register(testutils.NewFakeDriver("d2"), "d2"))
-	v, err = service.Get(ctx, "test", opts.WithGetDriver("d2"))
+	_, err = service.Get(ctx, "test", opts.WithGetDriver("d2"))
 	assert.Assert(t, errdefs.IsConflict(err), err)
 }