Bael 7616 (#15985)

* BAEL-7490 read write file in separate thread

* Change the to try resources

* Update the code to sync with article

* BAEL-7616 check if date object is yesterday

* Update test vars

* change the variable name prefix

* Update the test variable name

core-java-modules/core-java-date-operations-4/src/test/java/com/baeldung/compareyesterday/CompareYesterdayUnitTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.compareyesterday;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+
+import org.joda.time.DateTime;
+import org.junit.jupiter.api.Test;
+
+public class CompareYesterdayUnitTest {
+
+    @Test
+    void givenYesterdayDate_whenCompareWithCalendar_returnTrue() {
+        // To simulate yesterday
+        Date date = new Date(System.currentTimeMillis() - (1000 * 60 * 60 * 24));
+        Calendar expectedCalendar = Calendar.getInstance();
+        expectedCalendar.setTime(date);
+
+        Calendar actualCalendar = Calendar.getInstance();
+        actualCalendar.add(Calendar.DATE, -1);
+
+        boolean isEqualToYesterday = expectedCalendar.get(Calendar.YEAR) == actualCalendar.get(Calendar.YEAR) &&
+            expectedCalendar.get(Calendar.MONTH) == actualCalendar.get(Calendar.MONTH) &&
+            expectedCalendar.get(Calendar.DAY_OF_MONTH) == actualCalendar.get(Calendar.DAY_OF_MONTH);
+        assertTrue(isEqualToYesterday);
+    }
+
+    @Test
+    void givenTodayDate_whenCompareWithCalendar_returnFalse() {
+        Calendar expectedCalendar = Calendar.getInstance();
+
+        Calendar actualCalendar = Calendar.getInstance();
+        actualCalendar.add(Calendar.DATE, -1);
+
+        boolean isEqualToYesterday = expectedCalendar.get(Calendar.YEAR) == actualCalendar.get(Calendar.YEAR) &&
+            expectedCalendar.get(Calendar.MONTH) == actualCalendar.get(Calendar.MONTH) &&
+            expectedCalendar.get(Calendar.DAY_OF_MONTH) == actualCalendar.get(Calendar.DAY_OF_MONTH);
+        assertFalse(isEqualToYesterday);
+    }
+
+    @Test
+    void givenYesterdayDate_whenCompareWithDateMilliseconds_returnTrue() {
+        // Create a Date object representing yesterday
+        Date expectedDate = new Date(System.currentTimeMillis() - (1000 * 60 * 60 * 24));
+        long yesterdayMidnightMillis = Instant.now()
+            .minus(1, ChronoUnit.DAYS)
+            .toEpochMilli();
+
+        boolean isEqualToYesterday = expectedDate.getTime() >= yesterdayMidnightMillis && expectedDate.getTime() < yesterdayMidnightMillis + 86_400_000;
+        assertTrue(isEqualToYesterday);
+    }
+
+    @Test
+    void givenTodayDate_whenCompareWithDateMilliseconds_returnFalse() {
+        // Create a Date object representing yesterday
+        Date expectedDate = new Date();
+        long yesterdayMidnightMillis = Instant.now()
+            .minus(1, ChronoUnit.DAYS)
+            .toEpochMilli();
+
+        boolean isEqualToYesterday = expectedDate.getTime() >= yesterdayMidnightMillis && expectedDate.getTime() < yesterdayMidnightMillis + 86_400_000;
+        assertFalse(isEqualToYesterday);
+    }
+
+    @Test
+    void givenYesterdayDate_whenCompareWithLocalDate_returnTrue() {
+        // To simulate yesterday
+        Date date = new Date(System.currentTimeMillis() - (1000 * 60 * 60 * 24));
+        LocalDate expectedLocalDate = LocalDate.of(date.getYear() + 1900, date.getMonth() + 1, date.getDate());
+
+        LocalDate actualLocalDate = LocalDate.now()
+            .minusDays(1);
+        boolean isEqualToYesterday = expectedLocalDate.equals(actualLocalDate);
+        assertTrue(isEqualToYesterday);
+    }
+
+    @Test
+    void givenTodayDate_whenCompareWithLocalDate_returnFalse() {
+        LocalDate expectedLocalDate = LocalDate.now();
+        LocalDate actualLocalDate = LocalDate.now()
+            .minusDays(1);
+        boolean isEqualToYesterday = expectedLocalDate.equals(actualLocalDate);
+        assertFalse(isEqualToYesterday);
+    }
+
+    @Test
+    void givenYesterdayDate_whenCompareWithJodaTime_returnTrue() {
+        // To simulate yesterday
+        Date date = new Date(System.currentTimeMillis() - (1000 * 60 * 60 * 24));
+        DateTime expectedDateTime = new DateTime(date).withTimeAtStartOfDay();
+
+        DateTime actualDateTime = DateTime.now()
+            .minusDays(1)
+            .withTimeAtStartOfDay();
+
+        boolean isEqualToYesterday = expectedDateTime.equals(actualDateTime);
+        assertTrue(isEqualToYesterday);
+    }
+
+    @Test
+    void givenTodayDate_whenCompareWithJodaTime_returnFalse() {
+        DateTime expectedDateTime = DateTime.now()
+            .withTimeAtStartOfDay();
+        DateTime actualDateTime = DateTime.now()
+            .minusDays(1)
+            .withTimeAtStartOfDay();
+
+        boolean isEqualToYesterday = expectedDateTime.equals(actualDateTime);
+        assertFalse(isEqualToYesterday);
+    }
+}