poison: add test for PoisonedError

Release justification: testing only change
Release note: None

pkg/BUILD.bazel

@@ -139,6 +139,7 @@ ALL_TESTS = [
     "//pkg/kv/kvserver/closedts/sidetransport:sidetransport_test",
     "//pkg/kv/kvserver/closedts/tracker:tracker_test",
     "//pkg/kv/kvserver/closedts:closedts_test",
+    "//pkg/kv/kvserver/concurrency/poison:poison_test",
     "//pkg/kv/kvserver/concurrency:concurrency_test",
     "//pkg/kv/kvserver/gc:gc_test",
     "//pkg/kv/kvserver/idalloc:idalloc_test",

pkg/kv/kvserver/concurrency/poison/BUILD.bazel

@@ -1,5 +1,5 @@
 load("@rules_proto//proto:defs.bzl", "proto_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
 
 proto_library(
@@ -42,3 +42,20 @@ go_library(
         "@com_github_cockroachdb_errors//:errors",
     ],
 )
+
+go_test(
+    name = "poison_test",
+    srcs = ["error_test.go"],
+    data = glob(["testdata/**"]),
+    deps = [
+        ":poison",
+        "//pkg/keys",
+        "//pkg/roachpb",
+        "//pkg/testutils/echotest",
+        "//pkg/util/hlc",
+        "//pkg/util/leaktest",
+        "@com_github_cockroachdb_errors//:errors",
+        "@com_github_cockroachdb_redact//:redact",
+        "@com_github_stretchr_testify//require",
+    ],
+)

pkg/kv/kvserver/concurrency/poison/error.go

@@ -40,6 +40,3 @@ func (e *PoisonedError) Format(s fmt.State, verb rune) { errors.FormatError(e, s
 func (e *PoisonedError) Error() string {
 	return fmt.Sprint(e)
 }
-
-// TODO(tbg): need similar init() function that ReplicaUnavailableError has,
-// or PoisonError will not survive network round-trips.

pkg/kv/kvserver/concurrency/poison/error_test.go

@@ -0,0 +1,39 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package poison_test
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	_ "github.com/cockroachdb/cockroach/pkg/keys" // to init roachpb.PrettyPrintRange
+	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/concurrency/poison"
+	"github.com/cockroachdb/cockroach/pkg/roachpb"
+	"github.com/cockroachdb/cockroach/pkg/testutils/echotest"
+	"github.com/cockroachdb/cockroach/pkg/util/hlc"
+	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
+	"github.com/cockroachdb/errors"
+	"github.com/cockroachdb/redact"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPoisonedError(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	ctx := context.Background()
+	err := errors.DecodeError(ctx, errors.EncodeError(ctx, poison.NewPoisonedError(
+		roachpb.Span{Key: roachpb.Key("a")}, hlc.Timestamp{WallTime: 1},
+	)))
+	require.True(t, errors.HasType(err, (*poison.PoisonedError)(nil)), "%+v", err)
+	var buf redact.StringBuilder
+	buf.Printf("%s", err)
+	echotest.Require(t, string(buf.RedactableString()), filepath.Join("testdata", "poisoned_error.txt"))
+}

pkg/kv/kvserver/concurrency/poison/testdata/poisoned_error.txt

@@ -0,0 +1,3 @@
+echo
+----
+encountered poisoned latch ‹a›@0.000000001,0