Adjust hide until date

app/src/androidTest/java/org/tasks/ui/editviewmodel/DueDateTests.kt

@@ -0,0 +1,31 @@
+package org.tasks.ui.editviewmodel
+
+import com.natpryce.makeiteasy.MakeItEasy.with
+import com.todoroo.astrid.data.Task
+import dagger.hilt.android.testing.HiltAndroidTest
+import dagger.hilt.android.testing.UninstallModules
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.tasks.injection.ProductionModule
+import org.tasks.makers.TaskMaker
+import org.tasks.makers.TaskMaker.HIDE_TYPE
+import org.tasks.makers.TaskMaker.newTask
+import org.tasks.time.DateTime
+import java.util.concurrent.TimeUnit
+
+@UninstallModules(ProductionModule::class)
+@HiltAndroidTest
+class DueDateTests : BaseTaskEditViewModelTest() {
+    @Test
+    fun adjustHideUntilWhenChangingDate() {
+        val task = newTask(
+                with(TaskMaker.DUE_TIME, DateTime(2020, 7, 14, 16, 30, 0, 0)),
+                with(HIDE_TYPE, Task.HIDE_UNTIL_DUE_TIME))
+        setup(task)
+
+        val newDueDate = viewModel.dueDate!! + TimeUnit.DAYS.toMillis(1)
+        viewModel.dueDate = newDueDate
+
+        assertEquals(newDueDate, viewModel.hideUntil)
+    }
+}

app/src/main/java/org/tasks/ui/TaskEditViewModel.kt

@@ -89,12 +89,18 @@ class TaskEditViewModel @ViewModelInject constructor(
     var dueDate: Long? = null
         get() = field ?: task?.dueDate ?: 0
         set(value) {
+            val oldDueDate = dueDate!!
             field = when {
                 value == null -> null
                 value == 0L -> 0
                 hasDueTime(value) -> createDueDate(Task.URGENCY_SPECIFIC_DAY_TIME, value)
                 else -> createDueDate(Task.URGENCY_SPECIFIC_DAY, value)
             }
+            if (oldDueDate > 0) {
+                if (hideUntil!! > 0) {
+                    hideUntil = if (field!! > 0) hideUntil!! + field!! - oldDueDate else 0
+                }
+            }
         }
 
     var priority: Int? = null