diff --git a/README.md b/README.md
index da5c903..192c4f3 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ So this tools can help you create a rotation mechanism for it, by using the powe
 ```
 ./cir-rotator delete --service-account sa.json -ho asia.gcr.io/parent-repo \
                      --if "Now() - UploadedAt >= Duration('6M')  and ImageSize >= SizeStr('100 MiB')" \
-                     --ef "Repository matches '.*base-image$' and 'latest' in Tag" \
+                     --ef "Repository matches '.*base-image$' and 'latest' in Tags" \
                      --ef "Repository matches '.*internal-tools.*'"
 ```
 
diff --git a/app/cmd/cmd_test.go b/app/cmd/cmd_test.go
index 44eb629..66580c5 100644
--- a/app/cmd/cmd_test.go
+++ b/app/cmd/cmd_test.go
@@ -1,6 +1,7 @@
 package cmd_test
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
 	"io/ioutil"
@@ -11,6 +12,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/iomarmochtar/cir-rotator/app/cmd"
 	h "github.com/iomarmochtar/cir-rotator/pkg/helpers"
 	"github.com/stretchr/testify/assert"
 	cli "github.com/urfave/cli/v2"
@@ -122,3 +124,15 @@ func runCmdTestCases(name string, command *cli.Command, testCases map[string]cas
 		})
 	}
 }
+
+func TestNew(t *testing.T) {
+	// get version
+	buf := new(bytes.Buffer)
+	app := cmd.New()
+	app.Writer = buf
+	err := app.Run([]string{"cir-rotator", "--version"})
+	output := buf.String()
+
+	assert.NoError(t, err)
+	assert.Equal(t, fmt.Sprintf("cir-rotator version %s\n", app.Version), output)
+}
diff --git a/pkg/helpers/bytes_test.go b/pkg/helpers/bytes_test.go
new file mode 100644
index 0000000..58444c0
--- /dev/null
+++ b/pkg/helpers/bytes_test.go
@@ -0,0 +1,54 @@
+package helpers_test
+
+import (
+	"testing"
+
+	"github.com/iomarmochtar/cir-rotator/pkg/helpers"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestByteCountIEC(t *testing.T) {
+	assert.Equal(t, "984 B", helpers.ByteCountIEC(984), "under 1024")
+	assert.Equal(t, "505.8 MiB", helpers.ByteCountIEC(530325786), "upper 1024")
+}
+
+func TestSizeUnitStrToFloat(t *testing.T) {
+	testCase := map[string]struct {
+		expectedErrMsg string
+		result         float64
+		input          string
+	}{
+		"unknown pattern": {
+			input:          "1 KB",
+			expectedErrMsg: "unknown pattern 1 KB",
+		},
+		"invalid number": {
+			input:          "1.32.32 KiB",
+			expectedErrMsg: "unknown pattern 1.32.32 KiB",
+		},
+		"successfully converted KiB": {
+			input:  "1 KiB",
+			result: 1024,
+		},
+		"successfully converted MiB": {
+			input:  "1 MiB",
+			result: 1024 * 1024,
+		},
+		"successfully converted GiB": {
+			input:  "1 GiB",
+			result: 1024 * 1024 * 1024,
+		},
+	}
+
+	for title, tc := range testCase {
+		t.Run(title, func(t *testing.T) {
+			result, err := helpers.SizeUnitStrToFloat(tc.input)
+			if tc.expectedErrMsg != "" {
+				assert.EqualError(t, err, tc.expectedErrMsg)
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tc.result, result)
+		})
+	}
+}
diff --git a/pkg/helpers/helpers_test.go b/pkg/helpers/helpers_test.go
new file mode 100644
index 0000000..be4c84c
--- /dev/null
+++ b/pkg/helpers/helpers_test.go
@@ -0,0 +1,41 @@
+package helpers_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/iomarmochtar/cir-rotator/pkg/helpers"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsInList(t *testing.T) {
+	assert.True(t, helpers.IsInList(10, []int{3, 4, 10}))
+	assert.False(t, helpers.IsInList("adi", []string{"sorry", "not", "found"}))
+}
+
+func TestReadLines(t *testing.T) {
+	expectedLines := []string{`{"errors":[{"code":"NAME_UNKNOWN","message":"Failed to compute blob liveness for manifest: 'latest'"}]}`}
+	result, err := helpers.ReadLines("../../testdata/gcr/error_delete_manifest.json")
+	assert.NoError(t, err)
+	assert.Equal(t, expectedLines, result, "read the contents of file")
+
+	result, err = helpers.ReadLines("/this/path/is/not/found.txt")
+	assert.True(t, os.IsNotExist(err), "expected error for file not found")
+	assert.Empty(t, result)
+}
+
+func TestSlachJoin(t *testing.T) {
+	assert.Equal(t, "hello/world/gogo", helpers.SlashJoin("hello", "world", "gogo"))
+}
+
+func TestCombineMaps(t *testing.T) {
+	map1 := map[string]string{"name1": "val1", "name2": "val2"}
+	map2 := map[string]string{"name2": "val3", "name4": "val4"}
+	expected := map[string]string{"name1": "val1", "name2": "val3", "name4": "val4"}
+	assert.Equal(t, expected, helpers.CombineMaps(map1, map2))
+}
+
+func TestFileExist(t *testing.T) {
+	assert.True(t, helpers.FileExist("../../testdata/gcr/error_delete_manifest.json"))
+	assert.False(t, helpers.FileExist("/path/not/exists.txt"))
+}
diff --git a/pkg/helpers/time.go b/pkg/helpers/time.go
index 427c053..d921dfd 100644
--- a/pkg/helpers/time.go
+++ b/pkg/helpers/time.go
@@ -14,7 +14,7 @@ func ConvertTimeStrToUnix(timeStr string) (time.Time, error) {
 	if err != nil {
 		return time.Time{}, err
 	}
-	return time.Unix(parsed/unitMilliSecond, 0), nil
+	return time.Unix(parsed/unitMilliSecond, 0).UTC(), nil
 }
 
 func ConvertTimeStrToReadAble(timeStr string) (string, error) {
diff --git a/pkg/helpers/time_test.go b/pkg/helpers/time_test.go
new file mode 100644
index 0000000..917b532
--- /dev/null
+++ b/pkg/helpers/time_test.go
@@ -0,0 +1,29 @@
+package helpers_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/iomarmochtar/cir-rotator/pkg/helpers"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConvertTimeStrToUnix(t *testing.T) {
+	parsed, err := helpers.ConvertTimeStrToUnix("1585800237411")
+	assert.NoError(t, err)
+	assert.Equal(t, time.Date(2020, time.April, 2, 4, 3, 57, 0, time.UTC), parsed)
+
+	parsed, err = helpers.ConvertTimeStrToUnix("unknown")
+	assert.Error(t, err)
+	assert.Equal(t, time.Time{}, parsed)
+}
+
+func TestConvertTimeStrToReadAble(t *testing.T) {
+	parsed, err := helpers.ConvertTimeStrToReadAble("1585800237411")
+	assert.NoError(t, err)
+	assert.Equal(t, "2020-04-02T04:03:57Z", parsed, "parsed successfully")
+
+	parsed, err = helpers.ConvertTimeStrToReadAble("2022-06-13")
+	assert.Error(t, err, "wrong pattern")
+	assert.Equal(t, "", parsed)
+}
diff --git a/pkg/registry/gcr_test.go b/pkg/registry/gcr_test.go
index a435e67..47ab9bd 100644
--- a/pkg/registry/gcr_test.go
+++ b/pkg/registry/gcr_test.go
@@ -186,8 +186,8 @@ func TestGCR_Catalog(t *testing.T) {
 							Name:           "sha256:C05ce64163cd2327d364933df75aa4850af425b6cbaec2f6af3b31e5246be0e2",
 							ImageSizeBytes: 530325786,
 							Tag:            []string{"latest", "abc"},
-							Created:        time.Unix(1585800237411/1000, 0),
-							Uploaded:       time.Unix(1585800278141/1000, 0),
+							Created:        time.Unix(1585800237411/1000, 0).UTC(),
+							Uploaded:       time.Unix(1585800278141/1000, 0).UTC(),
 						},
 					},
 				},
@@ -198,8 +198,8 @@ func TestGCR_Catalog(t *testing.T) {
 							Name:           "sha256:02123554c8d65d241a77dd8e238403ba8cc697afca7208bbe7564b634aa22fee",
 							ImageSizeBytes: 365557176,
 							Tag:            []string{"latest", "release-20210624-150000"},
-							Created:        time.Unix(1624518709150/1000, 0),
-							Uploaded:       time.Unix(1624518770462/1000, 0),
+							Created:        time.Unix(1624518709150/1000, 0).UTC(),
+							Uploaded:       time.Unix(1624518770462/1000, 0).UTC(),
 						},
 					},
 				},