test(block/gs): run pre-signed URL test with fake-gcs-server

Add `nowFactory` injection and explicit signing credentials to enable
proper testing of GetPreSignedURL with `fake-gcs-server`. This follows
the same pattern used in the Azure adapter.

- Add WithNowFactory option to mock time.Now() for deterministic tests
- Add WithPresignedCredentials option for fake-gcs-server signing
- Remove "no credentials found" test skip workaround
- Include test RSA private key for URL signing

Author: skshetry

pkg/block/blocktest/adapter.go

@@ -230,10 +230,6 @@ func getPresignedURLBasicTest(t *testing.T, adapter block.Adapter, storageNamesp
 	if errors.Is(err, block.ErrOperationNotSupported) {
 		t.Skip("GetPreSignedURL not supported")
 	}
-	// Google storage returns an error if no credentials are found, and we can't sign the URL
-	if err != nil && strings.Contains(err.Error(), "no credentials found") {
-		t.Skip("GetPreSignedURL no credentials found")
-	}
 	require.NoError(t, err)
 	return preSignedURL, &exp
 }

pkg/block/gs/adapter.go

@@ -45,6 +45,11 @@ type Adapter struct {
 	disablePreSignedUI                   bool
 	ServerSideEncryptionCustomerSupplied []byte
 	ServerSideEncryptionKmsKeyID         string
+	nowFactory                           func() time.Time
+	// presignedGoogleAccessID and presignedPrivateKey are used for testing with fake-gcs-server
+	// which requires explicit signing credentials since the test client has no credentials
+	presignedGoogleAccessID string
+	presignedPrivateKey     []byte
 }
 
 func WithPreSignedExpiry(v time.Duration) func(a *Adapter) {
@@ -73,12 +78,28 @@ func WithDisablePreSignedUI(b bool) func(a *Adapter) {
 	}
 }
 
+func WithNowFactory(f func() time.Time) func(a *Adapter) {
+	return func(a *Adapter) {
+		a.nowFactory = f
+	}
+}
+
+// WithPresignedCredentials sets the Google Access ID and private key for signing URLs.
+// This is primarily used for testing with fake-gcs-server where the client has no credentials.
+func WithPresignedCredentials(googleAccessID string, privateKey []byte) func(a *Adapter) {
+	return func(a *Adapter) {
+		a.presignedGoogleAccessID = googleAccessID
+		a.presignedPrivateKey = privateKey
+	}
+}
+
 type AdapterOption func(a *Adapter)
 
 func NewAdapter(client *storage.Client, opts ...AdapterOption) *Adapter {
 	a := &Adapter{
 		client:          client,
 		preSignedExpiry: block.DefaultPreSignExpiryDuration,
+		nowFactory:      time.Now, // current time function can be mocked out via injection for testing purposes
 	}
 	for _, opt := range opts {
 		opt(a)
@@ -103,7 +124,7 @@ func (a *Adapter) log(ctx context.Context) logging.Logger {
 }
 
 func (a *Adapter) newPreSignedTime() time.Time {
-	return time.Now().UTC().Add(a.preSignedExpiry)
+	return a.nowFactory().UTC().Add(a.preSignedExpiry)
 }
 
 // withReadHandle returns a corresponding handle for reading object based on the encryption settings.
@@ -243,6 +264,12 @@ func (a *Adapter) GetPreSignedURL(ctx context.Context, obj block.ObjectPointer,
 		Expires: a.newPreSignedTime(),
 	}
 
+	// Use explicit signing credentials if provided (for testing with fake-gcs-server)
+	if a.presignedGoogleAccessID != "" && len(a.presignedPrivateKey) > 0 {
+		opts.GoogleAccessID = a.presignedGoogleAccessID
+		opts.PrivateKey = a.presignedPrivateKey
+	}
+
 	// Add content-disposition if filename provided
 	if mode == block.PreSignModeRead && filename != "" {
 		contentDisposition := mime.FormatMediaType("attachment", map[string]string{

pkg/block/gs/adapter_test.go

@@ -16,8 +16,42 @@ import (
 	"github.com/treeverse/lakefs/pkg/config"
 )
 
-func newAdapter() *gs.Adapter {
-	return gs.NewAdapter(client)
+// testGoogleAccessID is a fake Google Access ID used for testing signed URLs
+const testGoogleAccessID = "fake@test-project.iam.gserviceaccount.com"
+
+// testPrivateKey is a PEM-encoded RSA private key for testing signed URLs with fake-gcs-server.
+// This is a test-only key generated with: `openssl genrsa 2048`
+var testPrivateKey = []byte(`-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----`)
+
+func newAdapter(opts ...gs.AdapterOption) *gs.Adapter {
+	return gs.NewAdapter(client, opts...)
 }
 
 func TestAdapter(t *testing.T) {
@@ -28,7 +62,10 @@ func TestAdapter(t *testing.T) {
 	externalPath, err := url.JoinPath(basePath, "external")
 	require.NoError(t, err)
 
-	adapter := newAdapter()
+	adapter := newAdapter(
+		gs.WithNowFactory(blocktest.NowMockDefault),
+		gs.WithPresignedCredentials(testGoogleAccessID, testPrivateKey),
+	)
 	defer func() {
 		require.NoError(t, adapter.Close())
 	}()