tests: add unit tests for InMemoryBuffer

Author: wzieba

parsely/src/test/java/com/parsely/parselyandroid/InMemoryBufferTest.kt

@@ -0,0 +1,77 @@
+package com.parsely.parselyandroid
+
+import androidx.test.core.app.ApplicationProvider
+import kotlin.time.Duration.Companion.seconds
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.test.advanceTimeBy
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@RunWith(RobolectricTestRunner::class)
+internal class InMemoryBufferTest {
+
+    private lateinit var sut: InMemoryBuffer
+    private val repository = FakeLocalStorageRepository()
+
+    @Test
+    fun `when adding a new event, then save it to local storage`() = runTest {
+        // given
+        val event = mapOf("test" to 123)
+        sut = InMemoryBuffer(backgroundScope, repository)
+
+        // when
+        sut.add(event)
+        advanceTimeBy(1.seconds)
+        runCurrent()
+        backgroundScope.cancel()
+
+        // then
+        assertThat(repository.getStoredQueue()).containsOnlyOnce(event)
+    }
+
+    @Test
+    fun `when adding multiple events in different intervals, then save all of them to local storage without duplicates`() =
+        runTest {
+            // given
+            val events = (0..2).map { mapOf("test" to it) }
+            sut = InMemoryBuffer(backgroundScope, repository)
+
+            // when
+            sut.add(events[0])
+            advanceTimeBy(1.seconds)
+            runCurrent()
+
+            sut.add(events[1])
+            advanceTimeBy(0.5.seconds)
+            runCurrent()
+
+            sut.add(events[2])
+            advanceTimeBy(0.5.seconds)
+            runCurrent()
+
+            backgroundScope.cancel()
+
+            // then
+            assertThat(repository.getStoredQueue()).containsOnlyOnceElementsOf(events)
+        }
+
+    class FakeLocalStorageRepository() :
+        LocalStorageRepository(ApplicationProvider.getApplicationContext()) {
+
+        private val events = mutableListOf<Map<String, Any?>?>()
+
+        override suspend fun insertEvents(toInsert: List<Map<String, Any?>?>) {
+            events.addAll(toInsert)
+        }
+
+        override fun getStoredQueue(): ArrayList<Map<String, Any?>?> {
+            return ArrayList(events)
+        }
+    }
+}