Refactor and test DeferredAction. (#355)

formula/src/main/java/com/instacart/formula/DeferredAction.kt

@@ -5,13 +5,13 @@ package com.instacart.formula
  */
 class DeferredAction<Event>(
     val key: Any,
-    val action: Action<Event>,
+    private val action: Action<Event>,
     // We use event listener for equality because it provides better equality performance
-    val initial: (Event) -> Unit
+    private val initial: (Event) -> Unit
 ) {
+    private var cancelable: Cancelable? = null
 
     internal var listener: (Event) -> Unit = initial
-    internal var cancelable: Cancelable? = null
 
     internal fun start() {
         cancelable = action.start() { message ->
@@ -24,22 +24,15 @@ class DeferredAction<Event>(
         cancelable = null
     }
 
+    /**
+     * Action equality is based on the [initial] listener.
+     */
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
-        if (javaClass != other?.javaClass) return false
-
-        other as DeferredAction<*>
-
-        if (initial != other.initial) return false
-
-        return true
+        return other is DeferredAction<*> && initial == other.initial
     }
 
     override fun hashCode(): Int {
         return initial.hashCode()
     }
-
-    fun keyAsString(): String {
-        return key.toString()
-    }
 }

formula/src/test/java/com/instacart/formula/DeferredActionTest.kt

@@ -0,0 +1,31 @@
+package com.instacart.formula
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.Test
+
+class DeferredActionTest {
+
+    @Test
+    fun `identity equality returns true`() {
+        val callback = { _: Unit -> }
+        val action = DeferredAction(key = "1", action = Action.onInit(), callback)
+        assertThat(action.equals(action)).isTrue()
+    }
+
+    @Test
+    fun `when class is different, equality returns false`() {
+        val callback = { _: Unit -> }
+        val action = DeferredAction(key = "1", action = Action.onInit(), callback)
+        assertThat(action).isNotEqualTo("string")
+    }
+
+    @Test
+    fun `when listeners are not equal, the actions are not equal`() {
+        val callback = { _: Unit -> }
+        val callback2 = { _: Unit -> }
+        val action1 = DeferredAction(key = "1", action = Action.onInit(), callback)
+        val action2 = DeferredAction(key = "1", action = Action.onInit(), callback2)
+
+        assertThat(action1).isNotEqualTo(action2)
+    }
+}