Add Emitter class implementation and tests

README.md

@@ -51,8 +51,8 @@ We are breaking down the various parts that we need to migrate to Swift in the s
 |                     | SDK's `bucket.ts` ➡️ `Bucket.kt`                 | ✅      |
 |                     | SDK's `conditions.ts` ➡️ `Conditions.kt`         | ✅      |
 |                     | SDK's `datafileReader.ts` ➡️ `DatafileReader.kt` | ✅      |
-|                     | SDK's `emitter.ts` ➡️ `Emitter.kt`               | 🟠     |
-|                     | SDK's `feature.ts` ➡️ `Feature.kt`               |        |
+|                     | SDK's `emitter.ts` ➡️ `Emitter.kt`               | ✅      |
+|                     | SDK's `feature.ts` ➡️ `Feature.kt`               | 🟠     |
 |                     | SDK's `instance.ts` ➡️ `Instance.kt`             |        |
 |                     | SDK's `logger.ts` ➡️ `Logger.kt`                 |        |
 |                     | SDK's `segments.ts` ➡️ `segments.kt`             |        |

build.gradle.kts

@@ -49,7 +49,7 @@ dependencies {
     // Use the JUnit 5 integration.
     testImplementation("org.junit.jupiter:junit-jupiter-engine:5.9.2")
     // Uncomment when needed
-//    testImplementation("io.mockk:mockk:1.13.8")
+    testImplementation("io.mockk:mockk:1.13.8")
     testImplementation("io.kotest:kotest-assertions-core:5.7.2")
 
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")

src/main/kotlin/com/featurevisor/sdk/Emitter.kt

@@ -0,0 +1,23 @@
+package com.featurevisor.sdk
+
+import com.featurevisor.types.EventName
+
+class Emitter {
+    private val listeners = mutableMapOf<EventName, () -> Unit>()
+
+    fun addListener(event: EventName, listener: () -> Unit) {
+        listeners.putIfAbsent(event, listener)
+    }
+
+    fun removeListener(event: EventName) {
+        listeners.remove(event)
+    }
+
+    fun removeAllListeners() {
+        listeners.clear()
+    }
+
+    operator fun invoke(event: EventName) {
+        listeners.getOrDefault(event, null)?.invoke()
+    }
+}

src/main/kotlin/com/featurevisor/types/EventName.kt

@@ -0,0 +1,8 @@
+package com.featurevisor.types
+
+enum class EventName {
+    READY,
+    REFRESH,
+    UPDATE,
+    ACTIVATION,
+}

src/test/kotlin/com/featurevisor/sdk/EmitterTest.kt

@@ -0,0 +1,88 @@
+package com.featurevisor.sdk
+
+import com.featurevisor.types.EventName.ACTIVATION
+import com.featurevisor.types.EventName.READY
+import com.featurevisor.types.EventName.REFRESH
+import com.featurevisor.types.EventName.UPDATE
+import com.featurevisor.types.EventName.values
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.verify
+import org.junit.jupiter.api.Test
+
+class EmitterTest {
+
+    private val readyCallback: () -> Unit = mockk {
+        every { this@mockk() } answers { nothing }
+    }
+    private val refreshCallback: () -> Unit = mockk {
+        every { this@mockk() } answers { nothing }
+    }
+    private val updateCallback: () -> Unit = mockk {
+        every { this@mockk() } answers { nothing }
+    }
+    private val activationCallback: () -> Unit = mockk {
+        every { this@mockk() } answers { nothing }
+    }
+
+    private val systemUnderTest = Emitter()
+
+    @Test
+    fun `add listeners and confirm they are invoked`() {
+        systemUnderTest.addListener(READY, readyCallback)
+        systemUnderTest.addListener(REFRESH, refreshCallback)
+        systemUnderTest.addListener(UPDATE, updateCallback)
+        systemUnderTest.addListener(ACTIVATION, activationCallback)
+
+        values().forEach {
+            systemUnderTest.invoke(it)
+        }
+
+        verify(exactly = 1) {
+            readyCallback()
+            refreshCallback()
+            updateCallback()
+            activationCallback()
+        }
+    }
+
+    @Test
+    fun `removed listener is no longer invoked`() {
+        systemUnderTest.addListener(READY, readyCallback)
+        systemUnderTest.addListener(REFRESH, refreshCallback)
+        systemUnderTest.addListener(UPDATE, updateCallback)
+
+        systemUnderTest.removeListener(REFRESH)
+        values().forEach {
+            systemUnderTest.invoke(it)
+        }
+
+        verify(exactly = 1) {
+            readyCallback()
+            updateCallback()
+        }
+        verify(exactly = 0) {
+            refreshCallback()
+        }
+    }
+
+    @Test
+    fun `removeAllListeners() works correctly`() {
+        systemUnderTest.addListener(READY, readyCallback)
+        systemUnderTest.addListener(REFRESH, refreshCallback)
+        systemUnderTest.addListener(UPDATE, updateCallback)
+        systemUnderTest.addListener(ACTIVATION, activationCallback)
+
+        systemUnderTest.removeAllListeners()
+        values().forEach {
+            systemUnderTest.invoke(it)
+        }
+
+        verify(exactly = 0) {
+            readyCallback()
+            refreshCallback()
+            updateCallback()
+            activationCallback()
+        }
+    }
+}