Fix calculation of displayed dates range

Fix calculation of displayed dates range when one of the dates boundaries is defined and initial date is far from the defined date boundary. Add two unit tests to test this case.
CleverPumpkin · Aug 1, 2019 · 7da03b1 · 7da03b1
1 parent 4387281
commit 7da03b1
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Showing 2 changed files with 101 additions and 33 deletions.
diff --git a/crunchycalendar/src/main/java/ru/cleverpumpkin/calendar/utils/DisplayedDatesRangeFactory.kt b/crunchycalendar/src/main/java/ru/cleverpumpkin/calendar/utils/DisplayedDatesRangeFactory.kt
@@ -16,56 +16,65 @@ internal object DisplayedDatesRangeFactory {
 
     ): DatesRange {
 
-        val displayDatesFrom: CalendarDate
-        val displayDatesTo: CalendarDate
+        val rangeStart: CalendarDate
+        val rangeEnd: CalendarDate
 
         when {
             minDate == null && maxDate == null -> {
-                displayDatesFrom = initialDate.minusMonths(CalendarConst.MONTHS_PER_PAGE)
-                displayDatesTo = initialDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
+                rangeStart = initialDate.minusMonths(CalendarConst.MONTHS_PER_PAGE)
+                rangeEnd = initialDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
             }
 
             minDate != null && maxDate == null -> {
-                displayDatesFrom = minDate
-                displayDatesTo = displayDatesFrom.plusMonths(CalendarConst.MONTHS_PER_PAGE)
+                rangeStart = calculateRangeStart(minDate = minDate, initialDate = initialDate)
+                rangeEnd = rangeStart.plusMonths(CalendarConst.MONTHS_PER_PAGE)
             }
 
             minDate == null && maxDate != null -> {
-                displayDatesFrom = maxDate.minusMonths(CalendarConst.MONTHS_PER_PAGE)
-                displayDatesTo = maxDate
+                rangeEnd = calculateRangeEnd(maxDate = maxDate, initialDate = initialDate)
+                rangeStart = rangeEnd.minusMonths(CalendarConst.MONTHS_PER_PAGE)
             }
 
             minDate != null && maxDate != null -> {
                 if (initialDate.isBetween(minDate, maxDate)) {
-                    var monthsBetween = minDate.monthsBetween(initialDate)
-                    displayDatesFrom = if (monthsBetween > CalendarConst.MONTHS_PER_PAGE) {
-                        initialDate.minusMonths(CalendarConst.MONTHS_PER_PAGE)
-                    } else {
-                        minDate
-                    }
-
-                    monthsBetween = initialDate.monthsBetween(maxDate)
-                    displayDatesTo = if (monthsBetween > CalendarConst.MONTHS_PER_PAGE) {
-                        initialDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
-                    } else {
-                        maxDate
-                    }
+                    rangeStart = calculateRangeStart(minDate = minDate, initialDate = initialDate)
+                    rangeEnd = calculateRangeEnd(maxDate = maxDate, initialDate = initialDate)
                 } else {
-                    displayDatesFrom = minDate
-
-                    val monthBetween = minDate.monthsBetween(maxDate)
-                    displayDatesTo = if (monthBetween > CalendarConst.MONTHS_PER_PAGE) {
-                        minDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
-                    } else {
-                        maxDate
-                    }
+                    rangeStart = minDate
+                    rangeEnd = calculateRangeEnd(maxDate = maxDate, initialDate = minDate)
                 }
             }
 
             else -> throw IllegalStateException() // unreachable branch
         }
 
-        return DatesRange(dateFrom = displayDatesFrom, dateTo = displayDatesTo)
+        return DatesRange(dateFrom = rangeStart, dateTo = rangeEnd)
+    }
+
+    private fun calculateRangeStart(
+        minDate: CalendarDate,
+        initialDate: CalendarDate
+    ): CalendarDate {
+        val monthsBetween = minDate.monthsBetween(initialDate)
+
+        return if (monthsBetween > CalendarConst.MONTHS_PER_PAGE) {
+            initialDate.minusMonths(CalendarConst.MONTHS_PER_PAGE)
+        } else {
+            minDate
+        }
+    }
+
+    private fun calculateRangeEnd(
+        maxDate: CalendarDate,
+        initialDate: CalendarDate
+    ): CalendarDate {
+        val monthsBetween = initialDate.monthsBetween(maxDate)
+
+        return if (monthsBetween > CalendarConst.MONTHS_PER_PAGE) {
+            initialDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
+        } else {
+            maxDate
+        }
     }
 
 }
diff --git a/.../utils/DisplayedDatesRangeProviderTest.kt → ...r/utils/DisplayedDatesRangeFactoryTest.kt b/.../utils/DisplayedDatesRangeProviderTest.kt → ...r/utils/DisplayedDatesRangeFactoryTest.kt
@@ -5,6 +5,7 @@ import org.junit.Test
 import ru.cleverpumpkin.calendar.CalendarConst
 import ru.cleverpumpkin.calendar.CalendarDate
 import ru.cleverpumpkin.calendar.DatesRange
+import java.util.*
 
 /**
  * Set of unit tests for the [DisplayedDatesRangeFactory] class.
@@ -16,7 +17,7 @@ import ru.cleverpumpkin.calendar.DatesRange
  *
  * Created by Alexander Surinov on 29/04/2019.
  */
-class DisplayedDatesRangeProviderTest {
+class DisplayedDatesRangeFactoryTest {
 
     @Test
     fun `Get displayed dates range when min and max dates aren't defined, as a result correct dates range is returned`() {
@@ -43,7 +44,7 @@ class DisplayedDatesRangeProviderTest {
     }
 
     @Test
-    fun `Get displayed dates range when min date isn't defined and max date is defined, as a result correct dates range is returned`() {
+    fun `Get displayed dates range when min date is defined and max date isn't defined, as a result correct dates range is returned`() {
         // Given
         val minDate = CalendarDate.today
 
@@ -67,7 +68,7 @@ class DisplayedDatesRangeProviderTest {
     }
 
     @Test
-    fun `Get displayed dates range when min date is defined and max date isn't defined, as a result correct dates range is returned`() {
+    fun `Get displayed dates range when min date isn't defined and max date is defined, as a result correct dates range is returned`() {
         // Given
         val maxDate = CalendarDate.today
 
@@ -90,6 +91,64 @@ class DisplayedDatesRangeProviderTest {
         )
     }
 
+    @Test
+    fun `Get displayed dates range when min date is defined, max date isn't defined and initial date is far from min date, as a result correct dates range is returned`() {
+        // Given
+        val calendar = Calendar.getInstance()
+        calendar.set(2019, Calendar.JANUARY, 1)
+        val minDate = CalendarDate(calendar.time)
+
+        calendar.set(2019, Calendar.AUGUST, 1)
+        val initialDate = CalendarDate(calendar.time)
+
+        val expectedDatesRange = DatesRange(
+            dateFrom = initialDate.minusMonths(CalendarConst.MONTHS_PER_PAGE),
+            dateTo = initialDate
+        )
+
+        // When
+        val actualDatesRange = DisplayedDatesRangeFactory.getDisplayedDatesRange(
+            initialDate = CalendarDate.today,
+            minDate = minDate,
+            maxDate = null
+        )
+
+        // Then
+        Assert.assertTrue(
+            "Unexpected actual dates range: $actualDatesRange, expected: $expectedDatesRange",
+            expectedDatesRange == actualDatesRange
+        )
+    }
+
+    @Test
+    fun `Get displayed dates range when min date isn't defined, max date is defined and initial date is far from max date, as a result correct dates range is returned`() {
+        // Given
+        val calendar = Calendar.getInstance()
+        calendar.set(2019, Calendar.AUGUST, 1)
+        val maxDate = CalendarDate(calendar.time)
+
+        calendar.set(2019, Calendar.JANUARY, 1)
+        val initialDate = CalendarDate(calendar.time)
+
+        val expectedDatesRange = DatesRange(
+            dateFrom = initialDate,
+            dateTo = initialDate.plusMonths(CalendarConst.MONTHS_PER_PAGE)
+        )
+
+        // When
+        val actualDatesRange = DisplayedDatesRangeFactory.getDisplayedDatesRange(
+            initialDate = initialDate,
+            minDate = null,
+            maxDate = maxDate
+        )
+
+        // Then
+        Assert.assertTrue(
+            "Unexpected actual dates range: $actualDatesRange, expected: $expectedDatesRange",
+            expectedDatesRange == actualDatesRange
+        )
+    }
+
     @Test
     fun `Get displayed dates range when min-max dates are defined, initial dates is out of min-max date boundaries and days between min-max dates more then 6 month, as a result correct dates range is returned`() {
         // Given