Fix potential crash when searching contacts in forward sheet.

app/src/test/java/org/thoughtcrime/securesms/contacts/paged/collections/ContactSearchCollectionTest.kt

@@ -0,0 +1,121 @@
+package org.thoughtcrime.securesms.contacts.paged.collections
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.thoughtcrime.securesms.contacts.paged.ContactSearchConfiguration
+import org.thoughtcrime.securesms.contacts.paged.ContactSearchData
+
+class ContactSearchCollectionTest {
+
+  @Test
+  fun `When I get size, then I expect size of filtered content`() {
+    // GIVEN
+    val testSubject = createTestSubject()
+
+    // WHEN
+    val size = testSubject.getSize()
+
+    // THEN
+    assertEquals(5, size)
+  }
+
+  @Test
+  fun `When I get size with header, then I expect size of filtered content plus header`() {
+    // GIVEN
+    val testSubject = createTestSubject(includeHeader = true)
+
+    // WHEN
+    val size = testSubject.getSize()
+
+    // THEN
+    assertEquals(6, size)
+  }
+
+  @Test
+  fun `When I getSublist without 5, then I expect the corresponding values without 5`() {
+    // GIVEN
+    val testSubject = createTestSubject(
+      recordPredicate = { it != 5 }
+    )
+
+    // WHEN
+    val result = testSubject.getSublist(0, 9)
+
+    // THEN
+    assertEquals(listOf(0, 1, 2, 3, 4, 6, 7, 8, 9), result.filterIsInstance(ContactSearchData.TestRow::class.java).map { it.value })
+  }
+
+  @Test
+  fun `Given I got first page when I getSublist without 5, then I expect the corresponding values without 5`() {
+    // GIVEN
+    val testSubject = createTestSubject(
+      recordPredicate = { it != 5 }
+    )
+    testSubject.getSublist(0, 5)
+
+    // WHEN
+    val result = testSubject.getSublist(5, 9)
+
+    // THEN
+    assertEquals(listOf(6, 7, 8, 9), result.filterIsInstance(ContactSearchData.TestRow::class.java).map { it.value })
+  }
+
+  @Test
+  fun `Given I get second page with header, then I expect the corresponding values without 5`() {
+    // GIVEN
+    val testSubject = createTestSubject(
+      recordPredicate = { it != 5 },
+      includeHeader = true
+    )
+
+    // WHEN
+    val result = testSubject.getSublist(2, testSubject.getSize())
+
+    // THEN
+    assertEquals(listOf(1, 2, 3, 4, 6, 7, 8, 9), result.filterIsInstance(ContactSearchData.TestRow::class.java).map { it.value })
+  }
+
+  @Test
+  fun `Given I get entire page with header, then I expect the corresponding values without 5`() {
+    // GIVEN
+    val testSubject = createTestSubject(
+      recordPredicate = { it != 5 },
+      includeHeader = true
+    )
+
+    // WHEN
+    val result = testSubject.getSublist(0, testSubject.getSize())
+
+    // THEN
+    assertEquals(listOf(0, 1, 2, 3, 4, 6, 7, 8, 9), result.filterIsInstance(ContactSearchData.TestRow::class.java).map { it.value })
+  }
+
+  private fun createTestSubject(
+    size: Int = 10,
+    includeHeader: Boolean = false,
+    section: ContactSearchConfiguration.Section = ContactSearchConfiguration.Section.Groups(includeHeader = includeHeader),
+    records: ContactSearchIterator<Int> = FakeContactSearchIterator((0 until size).toList()),
+    recordPredicate: (Int) -> Boolean = { i -> i % 2 == 0 },
+    recordMapper: (Int) -> ContactSearchData = { i -> ContactSearchData.TestRow(i) },
+    activeContactCount: Int = 0
+  ): ContactSearchCollection<Int> {
+    return ContactSearchCollection(section, records, recordPredicate, recordMapper, activeContactCount)
+  }
+
+  private class FakeContactSearchIterator(private val numbers: List<Int>) : ContactSearchIterator<Int> {
+
+    private var position = -1
+
+    override fun hasNext(): Boolean = position < numbers.lastIndex
+
+    override fun next(): Int = numbers[++position]
+
+    override fun moveToPosition(n: Int) {
+      position = n
+    }
+
+    override fun getCount(): Int = numbers.size
+
+    override fun close() = Unit
+  }
+}