test(common): cover WAL restore error classification

Extract the barman-restorer error -> gRPC code switch from
restoreFromBarmanObjectStore into a pure helper,
classifyWALRestoreError, so it can be exercised in isolation
without the surrounding k8s client / configuration scaffolding.

Add ginkgo specs that check:

  - each barman sentinel maps to the expected gRPC status code
    (ErrConnectivity and ErrGeneric both -> Unavailable, since
    barman uses exit 4 for some retryable conditions too),
  - an unclassified error falls through to codes.Internal,
  - classification still works through multiple fmt.Errorf wraps,
  - the switch matches by errors.Is identity rather than message
    substring (so a NotFound whose message happens to mention
    "connectivity" still maps to NotFound).

internal/cnpgi/common had no tests before; this introduces the
suite scaffolding alongside the new specs.

Signed-off-by: Armando Ruocco <armando.ruocco@enterprisedb.com>

internal/cnpgi/common/errors.go

@@ -20,10 +20,38 @@ SPDX-License-Identifier: Apache-2.0
 package common
 
 import (
+	"errors"
+
+	barmanRestorer "github.com/cloudnative-pg/barman-cloud/pkg/restorer"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
 
+// classifyWALRestoreError maps an error returned by the WAL
+// restorer to a gRPC-coded error so the caller can tell terminal
+// failures apart from transient ones via the status code.
+func classifyWALRestoreError(walName string, walErr error) error {
+	switch {
+	case errors.Is(walErr, barmanRestorer.ErrWALNotFound):
+		return newWALNotFoundError(walName)
+	case errors.Is(walErr, barmanRestorer.ErrInvalidWalName):
+		// A malformed WAL name will never become valid on retry.
+		return newInvalidWALNameError(walName, walErr)
+	case errors.Is(walErr, barmanRestorer.ErrConnectivity),
+		errors.Is(walErr, barmanRestorer.ErrGeneric):
+		// barman-cloud exit codes 2 (connectivity) and 4
+		// (generic) both surface conditions that are retryable
+		// in practice — barman uses the "generic" bucket for
+		// some connection-class failures too, not just exit 2.
+		return newUnavailableError(walName, walErr)
+	default:
+		// Unrecognized exit codes and unexpected failures (e.g.
+		// the barman-cloud command could not be executed). No
+		// positive signal that retry would help.
+		return newInternalWALRestoreError(walName, walErr)
+	}
+}
+
 // ErrEndOfWALStreamReached is returned when end of WAL is detected in the cloud archive.
 var ErrEndOfWALStreamReached = status.Errorf(codes.OutOfRange, "end of WAL reached")
 

internal/cnpgi/common/errors_test.go

@@ -0,0 +1,86 @@
+/*
+Copyright © contributors to CloudNativePG, established as
+CloudNativePG a Series of LF Projects, LLC.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package common
+
+import (
+	"errors"
+	"fmt"
+
+	barmanRestorer "github.com/cloudnative-pg/barman-cloud/pkg/restorer"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+var _ = Describe("classifyWALRestoreError", func() {
+	const walName = "000000010000000000000001"
+
+	DescribeTable(
+		"maps barman restorer sentinels to gRPC status codes",
+		func(walErr error, expectedCode codes.Code) {
+			got := classifyWALRestoreError(walName, walErr)
+			Expect(got).To(HaveOccurred())
+
+			st, ok := status.FromError(got)
+			Expect(ok).To(BeTrue(), "returned error must carry a gRPC status")
+			Expect(st.Code()).To(Equal(expectedCode))
+			Expect(st.Message()).To(ContainSubstring(walName))
+		},
+		Entry("ErrWALNotFound -> NotFound",
+			fmt.Errorf("object storage or file not found: %w", barmanRestorer.ErrWALNotFound),
+			codes.NotFound),
+		Entry("ErrInvalidWalName -> InvalidArgument",
+			fmt.Errorf("invalid name for a WAL file: %w", barmanRestorer.ErrInvalidWalName),
+			codes.InvalidArgument),
+		Entry("ErrConnectivity -> Unavailable",
+			fmt.Errorf("connectivity failure, retrying: %w", barmanRestorer.ErrConnectivity),
+			codes.Unavailable),
+		Entry("ErrGeneric -> Unavailable (barman uses exit 4 for some retryable cases too)",
+			fmt.Errorf("generic error: %w", barmanRestorer.ErrGeneric),
+			codes.Unavailable),
+		Entry("unknown error -> Internal",
+			errors.New("something we did not classify"),
+			codes.Internal),
+	)
+
+	It("matches the sentinel even through several wrapping layers", func() {
+		// The plugin wraps barman errors via fmt.Errorf("...: %w", ...);
+		// classification must keep working if more wraps appear above.
+		inner := fmt.Errorf("connectivity failure, retrying: %w", barmanRestorer.ErrConnectivity)
+		wrapped := fmt.Errorf("while restoring WAL %s: %w", walName, inner)
+
+		got := classifyWALRestoreError(walName, wrapped)
+		st, ok := status.FromError(got)
+		Expect(ok).To(BeTrue())
+		Expect(st.Code()).To(Equal(codes.Unavailable))
+	})
+
+	It("treats ErrWALNotFound as terminal even when the error chain mentions other sentinels in its message", func() {
+		// Defensive: if the underlying error stringifies to something
+		// resembling another sentinel's message, the switch must still
+		// match by identity (errors.Is), not by substring.
+		walErr := fmt.Errorf("not found, looks like a connectivity failure: %w", barmanRestorer.ErrWALNotFound)
+
+		got := classifyWALRestoreError(walName, walErr)
+		st, _ := status.FromError(got)
+		Expect(st.Code()).To(Equal(codes.NotFound))
+	})
+})

internal/cnpgi/common/suite_test.go

@@ -0,0 +1,32 @@
+/*
+Copyright © contributors to CloudNativePG, established as
+CloudNativePG a Series of LF Projects, LLC.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package common
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestCommon(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Common Suite")
+}

internal/cnpgi/common/wal.go

@@ -365,29 +365,7 @@ func (w WALServiceImplementation) restoreFromBarmanObjectStore(
 	// is the one that PostgreSQL has requested to restore.
 	// The failure has already been logged in walRestorer.RestoreList method
 	if walStatus[0].Err != nil {
-		walName := walStatus[0].WalName
-		walErr := walStatus[0].Err
-		switch {
-		case errors.Is(walErr, barmanRestorer.ErrWALNotFound):
-			return newWALNotFoundError(walName)
-		case errors.Is(walErr, barmanRestorer.ErrInvalidWalName):
-			// A malformed WAL name will never become valid on retry.
-			return newInvalidWALNameError(walName, walErr)
-		case errors.Is(walErr, barmanRestorer.ErrConnectivity),
-			errors.Is(walErr, barmanRestorer.ErrGeneric):
-			// barman-cloud exit codes 2 (connectivity) and 4
-			// (generic) both surface conditions that are retryable
-			// in practice — barman uses the "generic" bucket for
-			// some connection-class failures too, not just exit 2.
-			// Emit codes.Unavailable so the caller retries.
-			return newUnavailableError(walName, walErr)
-		default:
-			// Unrecognized exit codes and unexpected failures
-			// (e.g. the barman-cloud command could not be
-			// executed). No positive signal that retry would
-			// help; emit codes.Internal.
-			return newInternalWALRestoreError(walName, walErr)
-		}
+		return classifyWALRestoreError(walStatus[0].WalName, walStatus[0].Err)
 	}
 
 	// We skip this step if streaming connection is not available