diff --git a/Makefile b/Makefile
index 454929b..6af7a0c 100644
--- a/Makefile
+++ b/Makefile
@@ -48,3 +48,8 @@ uninstall: clean
 .PHONY: start
 start: get-deps
 	go run ./cmd/app
+
+## test: Run unit tests
+.PHONY: test
+test:
+	@go test ./...
diff --git a/internal/utils/utils.go b/internal/utils/utils.go
index 631c0fa..aaaf9bf 100644
--- a/internal/utils/utils.go
+++ b/internal/utils/utils.go
@@ -2,7 +2,6 @@ package utils
 
 import (
 	"errors"
-	"fmt"
 	"math/rand/v2"
 	"os/exec"
 	"runtime"
@@ -35,10 +34,15 @@ func IsInWorkingHours(timeWindow string) bool {
 		return true
 	}
 
-	startTimeBefore := MakeRandomTime(parts[0])
-	endTimeAfter := MakeRandomTime(parts[1])
+	// Get the current date
 	currentTime := time.Now()
 
+	// Generate a datetime 3-14 minutes earlier than the specified time
+	startTimeBefore := addRandomTimeInterval(currentTime, parts[0])
+
+	// Generate a datetime 3-14 minutes later than the specified time
+	endTimeAfter := subtractRandomTimeInterval(currentTime, parts[1])
+
 	// Check if the current time is within the dynamic range
 	if currentTime.After(startTimeBefore) && currentTime.Before(endTimeAfter) {
 		return true
@@ -46,28 +50,37 @@ func IsInWorkingHours(timeWindow string) bool {
 	return false
 }
 
-func MakeRandomTime(inputTime string) time.Time {
-	// Parse input time like 19:00 to date time
-	parsedTime, err := time.Parse(timeLayout, inputTime)
+func addRandomTimeInterval(currentTime time.Time, inputTime string) time.Time {
+	shiftTime, err := time.Parse(timeLayout, inputTime)
 	if err != nil {
-		fmt.Println("Error parsing time:", err)
-		return time.Time{}
+		panic(err)
 	}
 
-	// Generate a random interval between 3 to 14 minutes
-	randomInterval := time.Duration(rand.N(12)+3) * time.Minute
+	shiftTime = shiftTime.Add(generateTimeInterval())
+
+	// Combine the current date with the parsed time
+	return combineNowAndShiftTime(currentTime, shiftTime)
+}
 
-	// Randomly decide whether to add or subtract the interval
-	if rand.N(2) == 0 {
-		parsedTime = parsedTime.Add(randomInterval)
-	} else {
-		parsedTime = parsedTime.Add(-randomInterval)
+func subtractRandomTimeInterval(currentTime time.Time, inputTime string) time.Time {
+	shiftTime, err := time.Parse(timeLayout, inputTime)
+	if err != nil {
+		panic(err)
 	}
 
-	// Get the current date
-	now := time.Now()
+	shiftTime = shiftTime.Add(-generateTimeInterval())
 
 	// Combine the current date with the parsed time
+	return combineNowAndShiftTime(currentTime, shiftTime)
+}
+
+// Generate a random interval between 3 to 14 minutes
+func generateTimeInterval() time.Duration {
+	return time.Duration(rand.N(12)+3) * time.Minute
+}
+
+// Combine the current date with the parsed time (hour-minute)
+func combineNowAndShiftTime(now, shiftTime time.Time) time.Time {
 	return time.Date(now.Year(), now.Month(), now.Day(),
-		parsedTime.Hour(), parsedTime.Minute(), parsedTime.Second(), 0, now.Location())
+		shiftTime.Hour(), shiftTime.Minute(), now.Second(), 0, now.Location())
 }
diff --git a/internal/utils/utils_test.go b/internal/utils/utils_test.go
new file mode 100644
index 0000000..49d0803
--- /dev/null
+++ b/internal/utils/utils_test.go
@@ -0,0 +1,28 @@
+package utils
+
+import (
+	"testing"
+	"time"
+)
+
+// Test value is within the range of 3 to 14 minutes
+func TestGenerateTimeInterval(t *testing.T) {
+	for range 100 {
+		result := generateTimeInterval()
+		if result < 3*time.Minute || result >= 15*time.Minute {
+			t.Errorf("generateTimeInterval() = %v, want %v to %v", result, 3*time.Minute, 15*time.Minute)
+		}
+	}
+}
+
+// Test checks if the function merges two times correctly
+func TestCombineNowAndShiftTime(t *testing.T) {
+	now := time.Date(2024, 4, 7, 10, 0, 45, 0, time.UTC)
+	shiftTime := time.Date(2000, 1, 1, 15, 30, 0, 0, time.UTC)
+	expected := time.Date(2024, 4, 7, 15, 30, 45, 0, time.UTC)
+	result := combineNowAndShiftTime(now, shiftTime)
+
+	if !result.Equal(expected) {
+		t.Errorf("combineNowAndShiftTime(%v, %v) = %v, want %v", now, shiftTime, result, expected)
+	}
+}