roachtest: add global monitor test

This change adds a test to ensure if the global monitor encounters an error that
the error is handled correctly and the test failed. It also ensures that the
framework does not panic, in the event of a monitor error.

Epic: None
Release note: None

Author: herkolategan

pkg/cmd/roachtest/BUILD.bazel

@@ -98,6 +98,7 @@ go_test(
         "main_test.go",
         "test_filter_test.go",
         "test_impl_test.go",
+        "test_monitor_test.go",
         "test_registry_test.go",
         "test_test.go",
         "zip_util_test.go",

pkg/cmd/roachtest/test_monitor_test.go

@@ -0,0 +1,77 @@
+// Copyright 2025 The Cockroach Authors.
+//
+// Use of this software is governed by the CockroachDB Software License
+// included in the /LICENSE file.
+
+package main
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/cockroachdb/cockroach/pkg/cmd/roachtest/cluster"
+	"github.com/cockroachdb/cockroach/pkg/cmd/roachtest/option"
+	"github.com/cockroachdb/cockroach/pkg/cmd/roachtest/registry"
+	"github.com/cockroachdb/cockroach/pkg/cmd/roachtest/spec"
+	"github.com/cockroachdb/cockroach/pkg/cmd/roachtest/test"
+	"github.com/cockroachdb/cockroach/pkg/util/stop"
+	"github.com/cockroachdb/errors"
+	"github.com/stretchr/testify/require"
+)
+
+type stubTestMonitorError struct{}
+
+func (s *stubTestMonitorError) ExpectProcessDead(
+	nodes option.NodeListOption, opts ...option.OptionFunc,
+) {
+}
+
+func (s *stubTestMonitorError) ExpectProcessAlive(
+	nodes option.NodeListOption, opts ...option.OptionFunc,
+) {
+}
+
+func (s *stubTestMonitorError) WaitForNodeDeath() error {
+	return errors.New("test error")
+}
+
+func TestGlobalMonitorError(t *testing.T) {
+	newTestMonitor = func(_ context.Context, t test.Test, c *clusterImpl) *testMonitorImpl {
+		return &testMonitorImpl{
+			monitor: &stubTestMonitorError{},
+			t:       t,
+		}
+	}
+
+	ctx := context.Background()
+	stopper := stop.NewStopper()
+	defer stopper.Stop(ctx)
+	cr := newClusterRegistry()
+	runner := newUnitTestRunner(cr, stopper)
+
+	var buf syncedBuffer
+	copt := defaultClusterOpt()
+	lopt := defaultLoggingOpt(&buf)
+
+	mockTest := registry.TestSpec{
+		Name:             `mock test`,
+		Owner:            OwnerUnitTest,
+		Cluster:          spec.MakeClusterSpec(0),
+		CompatibleClouds: registry.AllExceptAWS,
+		Suites:           registry.Suites(registry.Nightly),
+		CockroachBinary:  registry.StandardCockroach,
+		Monitor:          true,
+		Run: func(ctx context.Context, t test.Test, c cluster.Cluster) {
+			select {
+			case <-ctx.Done():
+				return
+			case <-time.After(5 * time.Minute):
+				return
+			}
+		},
+	}
+	err := runner.Run(ctx, []registry.TestSpec{mockTest}, 1, /* count */
+		defaultParallelism, copt, testOpts{}, lopt)
+	require.Error(t, err)
+}