Adds test for the isAchievement method

WordPress/src/test/java/org/wordpress/android/models/NoteExtensionsTest.kt

@@ -0,0 +1,28 @@
+package org.wordpress.android.models
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import org.junit.Test
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.whenever
+import org.wordpress.android.BaseUnitTest
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+@ExperimentalCoroutinesApi
+class NoteExtensionsTest : BaseUnitTest() {
+    @Test
+    fun `A comment_like note is not an achievement note`(){
+        val note = mock<Note>()
+        whenever(note.rawType).thenReturn("comment_like")
+        val result = note.isAchievement()
+        assertFalse(result)
+    }
+
+    @Test
+    fun `A user_goal_met note is an achievement note`(){
+        val note = mock<Note>()
+        whenever(note.rawType).thenReturn("user_goal_met")
+        val result = note.isAchievement()
+        assertTrue(result)
+    }
+}