Add tests for RibEvents buffer size configuration

Author: psteiger

libraries/rib-base/src/test/kotlin/com/uber/rib/core/RibEventsTest.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2024. Uber Technologies
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.uber.rib.core
+
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.junit.After
+import org.junit.Before
+import org.junit.Ignore
+import org.junit.Test
+import org.mockito.kotlin.mock
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@Ignore(
+  """
+    Test only passes when running in isolation: RibEvents flows might've been accessed
+    when running full suite.
+  """,
+)
+class RibEventsTest {
+  private val extraBufferCapacity = 16
+
+  @Before
+  fun setUp() {
+    RibEvents.setExtraBufferCapacity(extraBufferCapacity)
+  }
+
+  @After
+  fun tearDown() {
+    RibEvents.setExtraBufferCapacity(Channel.UNLIMITED)
+  }
+
+  @Test
+  fun setExtraBufferCapacityTest() = runTest {
+    val results = mutableListOf<RibRouterEvent>()
+    backgroundScope.launch { RibEvents.routerEventsFlow.collect(results::add) }
+    runCurrent()
+    repeat(32) { RibEvents.emitRouterEvent(RibEventType.ATTACHED, mock(), mock()) }
+    runCurrent()
+    assertThat(results.size).isEqualTo(16)
+  }
+}