test(nodepool): add coverage for osImageStream config hash, CAPI status, and error path

- Add "When rhelStream is set, it should change the hash" case to
  TestHash and TestHashWithoutVersion, verifying that changing
  rhelStream changes the hash and that empty rhelStream preserves
  backward-compatible values.
- Add expectedOSImageStream assertion to TestReconcileMachineDeploymentStatus,
  verifying status.osImageStream is set to rhel-9 on rollout completion
  with a 4.x release.
- Add error path case to TestGetRHELStream for unparseable version strings.

Signed-off-by: Salvatore Dario Minonne <sminonne@redhat.com>
Commit-Message-Assisted-by: Claude (via Claude Code)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sdminonne

hypershift-operator/controllers/nodepool/capi_test.go

@@ -2641,14 +2641,15 @@ func TestReconcileMachineDeploymentStatus(t *testing.T) {
 		nodePoolAnnotations          map[string]string
 		targetVersion                string
 		expectedVersion              string
+		expectedOSImageStream        string
 		expectedReplicas             int32
 		expectedConfigAnnotation     bool
 		expectedTemplateAnnotation   bool
 		expectedReadyConditionStatus corev1.ConditionStatus
 		expectedReadyConditionSet    bool
 	}{
 		{
-			name: "When MachineDeployment is complete, it should update nodePool version and annotations",
+			name: "When MachineDeployment is complete, it should update nodePool version and osImageStream",
 			machineDeployment: &capiv1.MachineDeployment{
 				ObjectMeta: metav1.ObjectMeta{Generation: 1},
 				Spec: capiv1.MachineDeploymentSpec{
@@ -2666,6 +2667,7 @@ func TestReconcileMachineDeploymentStatus(t *testing.T) {
 			nodePoolAnnotations:        map[string]string{},
 			targetVersion:              "4.17.0",
 			expectedVersion:            "4.17.0",
+			expectedOSImageStream:      "rhel-9",
 			expectedReplicas:           3,
 			expectedConfigAnnotation:   true,
 			expectedTemplateAnnotation: true,
@@ -2766,6 +2768,10 @@ func TestReconcileMachineDeploymentStatus(t *testing.T) {
 			g.Expect(nodePool.Status.Replicas).To(Equal(tc.expectedReplicas))
 			g.Expect(nodePool.Status.Version).To(Equal(tc.expectedVersion))
 
+			if tc.expectedOSImageStream != "" {
+				g.Expect(nodePool.Status.OSImageStream.Name).To(Equal(tc.expectedOSImageStream))
+			}
+
 			if tc.expectedConfigAnnotation {
 				g.Expect(nodePool.Annotations).To(HaveKey(nodePoolAnnotationCurrentConfig))
 			}

hypershift-operator/controllers/nodepool/config_test.go

@@ -434,6 +434,7 @@ func TestHash(t *testing.T) {
 		pullSecretName            string
 		additionalTrustBundleName string
 		globalConfig              string
+		rhelStream                string
 		expected                  string
 	}{
 		{
@@ -490,6 +491,16 @@ func TestHash(t *testing.T) {
 			globalConfig:              "different",
 			expected:                  "e916ddfe",
 		},
+		{
+			name:                      "When rhelStream is set, it should change the hash",
+			mcoRawConfig:              baseCaseMCORawConfig,
+			releaseVersion:            baseCaseReleaseVersion,
+			pullSecretName:            baseCasePullSecretName,
+			additionalTrustBundleName: baseCaseAdditionalTrustBundleName,
+			globalConfig:              baseCaseGlobalConfig,
+			rhelStream:                "rhel-10",
+			expected:                  "2dbbd41b",
+		},
 	}
 
 	for _, tc := range testCases {
@@ -508,6 +519,7 @@ func TestHash(t *testing.T) {
 					pullSecretName:            tc.pullSecretName,
 					additionalTrustBundleName: tc.additionalTrustBundleName,
 					globalConfig:              tc.globalConfig,
+					rhelStream:                tc.rhelStream,
 					releaseImage:              releaseImage,
 				},
 			}
@@ -536,6 +548,7 @@ func TestHashWithoutVersion(t *testing.T) {
 		pullSecretName            string
 		additionalTrustBundleName string
 		globalConfig              string
+		rhelStream                string
 		expected                  string
 	}{
 		{
@@ -594,6 +607,16 @@ func TestHashWithoutVersion(t *testing.T) {
 			globalConfig:              "different",
 			expected:                  baseCaseHash,
 		},
+		{
+			name:                      "When rhelStream is set, it should change the hash",
+			mcoRawConfig:              baseCaseMCORawConfig,
+			releaseVersion:            baseCaseReleaseVersion,
+			pullSecretName:            baseCasePullSecretName,
+			additionalTrustBundleName: baseCaseAdditionalTrustBundleName,
+			globalConfig:              baseCaseGlobalConfig,
+			rhelStream:                "rhel-10",
+			expected:                  "671fe083",
+		},
 	}
 
 	for _, tc := range testCases {
@@ -612,6 +635,7 @@ func TestHashWithoutVersion(t *testing.T) {
 					pullSecretName:            tc.pullSecretName,
 					additionalTrustBundleName: tc.additionalTrustBundleName,
 					globalConfig:              tc.globalConfig,
+					rhelStream:                tc.rhelStream,
 					releaseImage:              releaseImage,
 				},
 			}

hypershift-operator/controllers/nodepool/osstream_test.go

@@ -62,6 +62,16 @@ func TestGetRHELStream(t *testing.T) {
 			},
 			expectedStream: "rhel-10",
 		},
+		{
+			name: "When spec.osImageStream.Name is empty and version is unparseable, it should return an error",
+			nodePool: &hyperv1.NodePool{
+				Spec: hyperv1.NodePoolSpec{},
+			},
+			releaseImage: &releaseinfo.ReleaseImage{
+				ImageStream: &imageapi.ImageStream{ObjectMeta: metav1.ObjectMeta{Name: "not-a-version"}},
+			},
+			expectErr: true,
+		},
 	}
 
 	for _, tc := range testCases {