test: wait for COSI controller to be ready (#1014)

**What problem does this PR solve?**:
Missed this in
#1008
since I thought that all HCP are already checked.

**Which issue(s) this PR fixes**:
Fixes #

**How Has This Been Tested?**:
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Author: dkoshkin

test/e2e/addon_helpers.go

@@ -96,6 +96,17 @@ func WaitForAddonsToBeReadyInWorkloadCluster(
 		},
 	)
 
+	WaitForCOSIControllerToBeReadyInWorkloadCluster(
+		ctx,
+		WaitForCOSIControllerToBeReadyInWorkloadClusterInput{
+			COSI:                 input.AddonsConfig.COSI,
+			WorkloadCluster:      input.WorkloadCluster,
+			ClusterProxy:         input.ClusterProxy,
+			DeploymentIntervals:  input.DeploymentIntervals,
+			HelmReleaseIntervals: input.HelmReleaseIntervals,
+		},
+	)
+
 	WaitForServiceLoadBalancerToBeReadyInWorkloadCluster(
 		ctx,
 		WaitForServiceLoadBalancerToBeReadyInWorkloadClusterInput{

test/e2e/cosi_helpers.go

@@ -0,0 +1,74 @@
+//go:build e2e
+
+// Copyright 2025 Nutanix. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package e2e
+
+import (
+	"context"
+	"fmt"
+
+	. "github.com/onsi/ginkgo/v2"
+	appsv1 "k8s.io/api/apps/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/utils/ptr"
+	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
+	"sigs.k8s.io/cluster-api/test/framework"
+
+	"github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/api/v1alpha1"
+	apivariables "github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/api/variables"
+)
+
+type WaitForCOSIControllerToBeReadyInWorkloadClusterInput struct {
+	COSI                 *apivariables.COSI
+	WorkloadCluster      *clusterv1.Cluster
+	ClusterProxy         framework.ClusterProxy
+	DeploymentIntervals  []interface{}
+	HelmReleaseIntervals []interface{}
+}
+
+func WaitForCOSIControllerToBeReadyInWorkloadCluster(
+	ctx context.Context,
+	input WaitForCOSIControllerToBeReadyInWorkloadClusterInput, //nolint:gocritic // This hugeParam is OK in tests.
+) {
+	if input.COSI == nil {
+		return
+	}
+
+	switch ptr.Deref(input.COSI.Strategy, "") {
+	case v1alpha1.AddonStrategyHelmAddon:
+		WaitForHelmReleaseProxyReadyForCluster(
+			ctx,
+			WaitForHelmReleaseProxyReadyForClusterInput{
+				GetLister:       input.ClusterProxy.GetClient(),
+				Cluster:         input.WorkloadCluster,
+				HelmReleaseName: "cosi-controller",
+			},
+			input.HelmReleaseIntervals...,
+		)
+	case "":
+		Fail("COSI strategy is not set")
+	default:
+		Fail(
+			fmt.Sprintf(
+				"Do not know how to wait for COSI using strategy %s to be ready",
+				*input.COSI.Strategy,
+			),
+		)
+	}
+
+	workloadClusterClient := input.ClusterProxy.GetWorkloadCluster(
+		ctx, input.WorkloadCluster.Namespace, input.WorkloadCluster.Name,
+	).GetClient()
+
+	WaitForDeploymentsAvailable(ctx, framework.WaitForDeploymentsAvailableInput{
+		Getter: workloadClusterClient,
+		Deployment: &appsv1.Deployment{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "container-object-storage-controller",
+				Namespace: "container-object-storage-system",
+			},
+		},
+	}, input.DeploymentIntervals...)
+}