diff --git a/changelogs/unreleased/6296-Lyndon-Li b/changelogs/unreleased/6296-Lyndon-Li
new file mode 100644
index 000000000..69c0b5ed3
--- /dev/null
+++ b/changelogs/unreleased/6296-Lyndon-Li
@@ -0,0 +1 @@
+Add UT cases for pkg/repository
\ No newline at end of file
diff --git a/pkg/repository/config/azure_test.go b/pkg/repository/config/azure_test.go
index f32f87ce0..87cd31bf1 100644
--- a/pkg/repository/config/azure_test.go
+++ b/pkg/repository/config/azure_test.go
@@ -132,3 +132,47 @@ func TestGetStorageDomainFromCloudName(t *testing.T) {
 		})
 	}
 }
+
+func TestGetRequiredValues(t *testing.T) {
+	testCases := []struct {
+		name string
+		mp   map[string]string
+		keys []string
+		err  string
+	}{
+		{
+			name: "with miss",
+			mp: map[string]string{
+				"key1": "value1",
+			},
+			keys: []string{"key1", "key2", "key3"},
+			err:  "the following keys do not have values: key2, key3",
+		},
+		{
+			name: "without miss",
+			mp: map[string]string{
+				"key1": "value1",
+				"key2": "value2",
+				"key3": "value3",
+			},
+			keys: []string{"key1", "key2", "key3"},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := getRequiredValues(func(key string) string {
+				if tc.mp == nil {
+					return ""
+				} else {
+					return tc.mp[key]
+				}
+			}, tc.keys...)
+
+			if err == nil {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.err)
+			}
+		})
+	}
+}
diff --git a/pkg/repository/ensurer_test.go b/pkg/repository/ensurer_test.go
new file mode 100644
index 000000000..c9e71ea8c
--- /dev/null
+++ b/pkg/repository/ensurer_test.go
@@ -0,0 +1,198 @@
+/*
+Copyright the Velero contributors.
+
+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.
+*/
+
+package repository
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client/fake"
+
+	velerov1 "github.com/vmware-tanzu/velero/pkg/apis/velero/v1"
+	velerotest "github.com/vmware-tanzu/velero/pkg/test"
+)
+
+func TestEnsureRepo(t *testing.T) {
+	bkRepoObj := newBackupRepository(velerov1.DefaultNamespace, BackupRepositoryKey{
+		VolumeNamespace: "fake-ns",
+		BackupLocation:  "fake-bsl",
+		RepositoryType:  "fake-repo-type",
+	})
+
+	bkRepoObj.Status.Phase = velerov1.BackupRepositoryPhaseReady
+
+	scheme := runtime.NewScheme()
+	velerov1.AddToScheme(scheme)
+
+	tests := []struct {
+		name           string
+		namespace      string
+		bsl            string
+		repositoryType string
+		kubeClientObj  []runtime.Object
+		runtimeScheme  *runtime.Scheme
+		expectedRepo   *velerov1.BackupRepository
+		err            string
+	}{
+		{
+			name:           "namespace is empty",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			err:            "wrong parameters, namespace \"\", backup storage location \"fake-bsl\", repository type \"fake-repo-type\"",
+		},
+		{
+			name:           "bsl is empty",
+			namespace:      "fake-ns",
+			repositoryType: "fake-repo-type",
+			err:            "wrong parameters, namespace \"fake-ns\", backup storage location \"\", repository type \"fake-repo-type\"",
+		},
+		{
+			name:      "repositoryType is empty",
+			namespace: "fake-ns",
+			bsl:       "fake-bsl",
+			err:       "wrong parameters, namespace \"fake-ns\", backup storage location \"fake-bsl\", repository type \"\"",
+		},
+		{
+			name:           "get repo fail",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			err:            "error getting backup repository list: no kind is registered for the type v1.BackupRepositoryList in scheme \"pkg/runtime/scheme.go:100\"",
+		},
+		{
+			name:           "success on existing repo",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			kubeClientObj: []runtime.Object{
+				bkRepoObj,
+			},
+			runtimeScheme: scheme,
+			expectedRepo:  bkRepoObj,
+		},
+		{
+			name:           "create fail",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			runtimeScheme:  scheme,
+			err:            "failed to wait BackupRepository: timed out waiting for the condition",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeClientBuilder := fake.NewClientBuilder()
+			if test.runtimeScheme != nil {
+				fakeClientBuilder = fakeClientBuilder.WithScheme(test.runtimeScheme)
+			}
+
+			fakeClient := fakeClientBuilder.WithRuntimeObjects(test.kubeClientObj...).Build()
+
+			ensurer := NewEnsurer(fakeClient, velerotest.NewLogger(), time.Millisecond)
+
+			repo, err := ensurer.EnsureRepo(context.Background(), velerov1.DefaultNamespace, test.namespace, test.bsl, test.repositoryType)
+			if err != nil {
+				assert.EqualError(t, err, test.err)
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, test.expectedRepo, repo)
+		})
+	}
+}
+
+func TestCreateBackupRepositoryAndWait(t *testing.T) {
+	bkRepoObj := newBackupRepository(velerov1.DefaultNamespace, BackupRepositoryKey{
+		VolumeNamespace: "fake-ns",
+		BackupLocation:  "fake-bsl",
+		RepositoryType:  "fake-repo-type",
+	})
+
+	bkRepoObj.Status.Phase = velerov1.BackupRepositoryPhaseReady
+
+	scheme := runtime.NewScheme()
+	velerov1.AddToScheme(scheme)
+
+	tests := []struct {
+		name           string
+		namespace      string
+		bsl            string
+		repositoryType string
+		kubeClientObj  []runtime.Object
+		runtimeScheme  *runtime.Scheme
+		expectedRepo   *velerov1.BackupRepository
+		err            string
+	}{
+		{
+			name:           "create fail",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			err:            "unable to create backup repository resource: no kind is registered for the type v1.BackupRepository in scheme \"pkg/runtime/scheme.go:100\"",
+		},
+		{
+			name:           "get repo fail",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			kubeClientObj: []runtime.Object{
+				bkRepoObj,
+			},
+			runtimeScheme: scheme,
+			err:           "failed to wait BackupRepository: more than one BackupRepository found for workload namespace \"fake-ns\", backup storage location \"fake-bsl\", repository type \"fake-repo-type\"",
+		},
+		{
+			name:           "wait repo fail",
+			namespace:      "fake-ns",
+			bsl:            "fake-bsl",
+			repositoryType: "fake-repo-type",
+			runtimeScheme:  scheme,
+			err:            "failed to wait BackupRepository: timed out waiting for the condition",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeClientBuilder := fake.NewClientBuilder()
+			if test.runtimeScheme != nil {
+				fakeClientBuilder = fakeClientBuilder.WithScheme(test.runtimeScheme)
+			}
+
+			fakeClient := fakeClientBuilder.WithRuntimeObjects(test.kubeClientObj...).Build()
+
+			ensurer := NewEnsurer(fakeClient, velerotest.NewLogger(), time.Millisecond)
+
+			repo, err := ensurer.createBackupRepositoryAndWait(context.Background(), velerov1.DefaultNamespace, BackupRepositoryKey{
+				VolumeNamespace: test.namespace,
+				BackupLocation:  test.bsl,
+				RepositoryType:  test.repositoryType,
+			})
+			if err != nil {
+				assert.EqualError(t, err, test.err)
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, test.expectedRepo, repo)
+		})
+	}
+}
diff --git a/pkg/repository/udmrepo/kopialib/lib_repo_test.go b/pkg/repository/udmrepo/kopialib/lib_repo_test.go
index 19b2089a8..8c01827ae 100644
--- a/pkg/repository/udmrepo/kopialib/lib_repo_test.go
+++ b/pkg/repository/udmrepo/kopialib/lib_repo_test.go
@@ -405,3 +405,311 @@ func TestShouldLog(t *testing.T) {
 		})
 	}
 }
+
+func TestOpenObject(t *testing.T) {
+	testCases := []struct {
+		name        string
+		rawRepo     *repomocks.DirectRepository
+		objectID    string
+		retErr      error
+		expectedErr string
+	}{
+		{
+			name:        "raw repo is nil",
+			expectedErr: "repo is closed or not open",
+		},
+		{
+			name:        "objectID is invalid",
+			rawRepo:     repomocks.NewDirectRepository(t),
+			objectID:    "fake-id",
+			expectedErr: "error to parse object ID from fake-id: malformed content ID: \"fake-id\": invalid content prefix",
+		},
+		{
+			name:        "raw open fail",
+			rawRepo:     repomocks.NewDirectRepository(t),
+			retErr:      errors.New("fake-open-error"),
+			expectedErr: "error to open object: fake-open-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawRepo != nil {
+				if tc.retErr != nil {
+					tc.rawRepo.On("OpenObject", mock.Anything, mock.Anything).Return(nil, tc.retErr)
+				}
+
+				kr.rawRepo = tc.rawRepo
+			}
+
+			_, err := kr.OpenObject(context.Background(), udmrepo.ID(tc.objectID))
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestGetManifest(t *testing.T) {
+	testCases := []struct {
+		name        string
+		rawRepo     *repomocks.DirectRepository
+		retErr      error
+		expectedErr string
+	}{
+		{
+			name:        "raw repo is nil",
+			expectedErr: "repo is closed or not open",
+		},
+		{
+			name:        "raw get fail",
+			rawRepo:     repomocks.NewDirectRepository(t),
+			retErr:      errors.New("fake-get-error"),
+			expectedErr: "error to get manifest: fake-get-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawRepo != nil {
+				if tc.retErr != nil {
+					tc.rawRepo.On("GetManifest", mock.Anything, mock.Anything, mock.Anything).Return(nil, tc.retErr)
+				}
+
+				kr.rawRepo = tc.rawRepo
+			}
+
+			err := kr.GetManifest(context.Background(), udmrepo.ID(""), &udmrepo.RepoManifest{})
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestFindManifests(t *testing.T) {
+	testCases := []struct {
+		name        string
+		rawRepo     *repomocks.DirectRepository
+		retErr      error
+		expectedErr string
+	}{
+		{
+			name:        "raw repo is nil",
+			expectedErr: "repo is closed or not open",
+		},
+		{
+			name:        "raw find fail",
+			rawRepo:     repomocks.NewDirectRepository(t),
+			retErr:      errors.New("fake-find-error"),
+			expectedErr: "error to find manifests: fake-find-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawRepo != nil {
+				tc.rawRepo.On("FindManifests", mock.Anything, mock.Anything).Return(nil, tc.retErr)
+				kr.rawRepo = tc.rawRepo
+			}
+
+			_, err := kr.FindManifests(context.Background(), udmrepo.ManifestFilter{})
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestClose(t *testing.T) {
+	testCases := []struct {
+		name            string
+		rawRepo         *repomocks.DirectRepository
+		rawWriter       *repomocks.DirectRepositoryWriter
+		rawRepoRetErr   error
+		rawWriterRetErr error
+		expectedErr     string
+	}{
+		{
+			name: "both nil",
+		},
+		{
+			name:      "writer is not nil",
+			rawWriter: repomocks.NewDirectRepositoryWriter(t),
+		},
+		{
+			name:    "repo is not nil",
+			rawRepo: repomocks.NewDirectRepository(t),
+		},
+		{
+			name:            "writer close error",
+			rawWriter:       repomocks.NewDirectRepositoryWriter(t),
+			rawWriterRetErr: errors.New("fake-writer-close-error"),
+			expectedErr:     "error to close repo writer: fake-writer-close-error",
+		},
+		{
+			name:          "repo is not nil",
+			rawRepo:       repomocks.NewDirectRepository(t),
+			rawRepoRetErr: errors.New("fake-repo-close-error"),
+			expectedErr:   "error to close repo: fake-repo-close-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawRepo != nil {
+				tc.rawRepo.On("Close", mock.Anything).Return(tc.rawRepoRetErr)
+				kr.rawRepo = tc.rawRepo
+			}
+
+			if tc.rawWriter != nil {
+				tc.rawWriter.On("Close", mock.Anything).Return(tc.rawWriterRetErr)
+				kr.rawWriter = tc.rawWriter
+			}
+
+			err := kr.Close(context.Background())
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestPutManifest(t *testing.T) {
+	testCases := []struct {
+		name            string
+		rawWriter       *repomocks.DirectRepositoryWriter
+		rawWriterRetErr error
+		expectedErr     string
+	}{
+		{
+			name:        "raw writer is nil",
+			expectedErr: "repo writer is closed or not open",
+		},
+		{
+			name:            "raw put fail",
+			rawWriter:       repomocks.NewDirectRepositoryWriter(t),
+			rawWriterRetErr: errors.New("fake-writer-put-error"),
+			expectedErr:     "error to put manifest: fake-writer-put-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawWriter != nil {
+				tc.rawWriter.On("PutManifest", mock.Anything, mock.Anything, mock.Anything).Return(manifest.ID(""), tc.rawWriterRetErr)
+				kr.rawWriter = tc.rawWriter
+			}
+
+			_, err := kr.PutManifest(context.Background(), udmrepo.RepoManifest{
+				Metadata: &udmrepo.ManifestEntryMetadata{},
+			})
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestDeleteManifest(t *testing.T) {
+	testCases := []struct {
+		name            string
+		rawWriter       *repomocks.DirectRepositoryWriter
+		rawWriterRetErr error
+		expectedErr     string
+	}{
+		{
+			name:        "raw writer is nil",
+			expectedErr: "repo writer is closed or not open",
+		},
+		{
+			name:            "raw delete fail",
+			rawWriter:       repomocks.NewDirectRepositoryWriter(t),
+			rawWriterRetErr: errors.New("fake-writer-delete-error"),
+			expectedErr:     "error to delete manifest: fake-writer-delete-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawWriter != nil {
+				tc.rawWriter.On("DeleteManifest", mock.Anything, mock.Anything).Return(tc.rawWriterRetErr)
+				kr.rawWriter = tc.rawWriter
+			}
+
+			err := kr.DeleteManifest(context.Background(), udmrepo.ID(""))
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}
+
+func TestFlush(t *testing.T) {
+	testCases := []struct {
+		name            string
+		rawWriter       *repomocks.DirectRepositoryWriter
+		rawWriterRetErr error
+		expectedErr     string
+	}{
+		{
+			name:        "raw writer is nil",
+			expectedErr: "repo writer is closed or not open",
+		},
+		{
+			name:            "raw flush fail",
+			rawWriter:       repomocks.NewDirectRepositoryWriter(t),
+			rawWriterRetErr: errors.New("fake-writer-flush-error"),
+			expectedErr:     "error to flush repo: fake-writer-flush-error",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kr := &kopiaRepository{}
+
+			if tc.rawWriter != nil {
+				tc.rawWriter.On("Flush", mock.Anything).Return(tc.rawWriterRetErr)
+				kr.rawWriter = tc.rawWriter
+			}
+
+			err := kr.Flush(context.Background())
+
+			if tc.expectedErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.expectedErr)
+			}
+		})
+	}
+}