chore: Controller 및 DateProvider 테스트 코드 작성

- DateProviderTest: findNearestWeekDay() 관련 테스트 코드 작성
- EveryCalendarControllerTest: URL validate 관련 테스트 코드 작성
issue: #35

src/test/java/dev/whteb/everyCalendar/Controller/EveryCalendarControllerTest.java

@@ -0,0 +1,20 @@
+package dev.whteb.everyCalendar.Controller;
+
+
+import dev.whteb.everyCalendar.DTO.GetIcsDTO;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+class EveryCalendarControllerTest {
+
+    @Test
+    void 캘린더_URL이_잘못된_경우_예외를_던진다() {
+        EveryCalendarController everyCalendarController = new EveryCalendarController(null);
+        Assertions.assertThrows(Exception.class, () -> {
+            everyCalendarController.getIcs(new GetIcsDTO("https://whiteb.dev/@3a123adkl1", new Date(), new Date()), null);
+        });
+
+    }
+}

src/test/java/dev/whteb/everyCalendar/Provider/DateProviderTest.java

@@ -0,0 +1,45 @@
+package dev.whteb.everyCalendar.Provider;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class DateProviderTest {
+    static Date base;
+    static DateProvider dateProvider;
+    @BeforeAll
+    static void beforeAll() {
+        base = getSpecificDate(2024, Calendar.JANUARY, 5);
+        dateProvider = new DateProvider();
+        System.out.println("base = " + base);
+    }
+
+    @Test
+    void 특정_요일_가장_가까운_날짜를_반환한다() {
+        Date thursday = dateProvider.findNearestWeekDay(Calendar.THURSDAY, base);
+        System.out.println("thursday = " + thursday);
+        assertThat(thursday).isEqualTo(getSpecificDate(2024, Calendar.JANUARY, 11));
+    }
+
+    @Test
+    void 시작일은_기간에_포함된다() {
+        Date friday = dateProvider.findNearestWeekDay(Calendar.FRIDAY, base);
+        System.out.println("friday = " + friday);
+        assertThat(friday.getTime()).isEqualTo(base.getTime());
+    }
+
+    static Date getSpecificDate(int year, int month, int date) {
+        Calendar calendar = Calendar.getInstance(Locale.KOREA);
+        calendar.setTimeZone(TimeZone.getTimeZone("Asia/Seoul"));
+        calendar.setTimeInMillis(0);
+        calendar.set(year, month, date, 0, 0, 0);
+        return new Date(calendar.getTimeInMillis());
+    }
+
+}