Fix bug where onDetach is called before onAttach

scoop/src/main/java/com/lyft/scoop/ViewController.java

@@ -4,14 +4,18 @@
 
 public abstract class ViewController {
 
+    private boolean isDetaching = false;
     private boolean attached;
     private Scoop scoop;
     private View view;
 
     final void attach(View view) {
-        this.attached = true;
         this.view = view;
         onAttach();
+        this.attached = true;
+        if (this.isDetaching) {
+            detach(view);
+        }
     }
 
     public void onAttach() {}
@@ -21,9 +25,13 @@ protected final boolean attached() {
     }
 
     final void detach(View view) {
-        onDetach();
-        this.view = null;
-        this.attached = false;
+        this.isDetaching = true;
+        if(this.attached) {
+            onDetach();
+            this.view = null;
+            this.attached = false;
+            this.isDetaching = false;
+        }
     }
 
     public void onDetach() {}

scoop/src/test/java/com/lyft/scoop/ViewControllerTest.java

@@ -0,0 +1,69 @@
+package com.lyft.scoop;
+
+import android.content.Context;
+import android.view.View;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class ViewControllerTest {
+    private static final String TEST_RESULT = "TEST_RESULT";
+
+    private MockViewController viewController;
+    private View mockView;
+
+    @Before
+    public void setUp() {
+        viewController = new MockViewController();
+        mockView = new TestView(RuntimeEnvironment.application);
+    }
+    @Test
+    public void onAttachFirst() {
+        viewController.attach(mockView);
+        assertTrue(viewController.attached());
+        viewController.detach(mockView);
+        assertFalse(viewController.attached());
+    }
+
+    @Test
+    public void onDetachFirst() {
+        viewController.detach(mockView);
+        assertFalse(viewController.attached());
+        viewController.attach(mockView);
+        assertFalse(viewController.attached());
+    }
+
+    private class MockViewController extends ViewController {
+        private String variable = null;
+
+        @Override
+        public void onAttach() {
+            variable = TEST_RESULT;
+        }
+
+        @Override
+        public void onDetach() {
+            variable.toString();
+        }
+
+        @Override
+        protected int layoutId() {
+            return 0;
+        }
+    }
+
+    static class TestView extends View {
+
+        public TestView(Context context) {
+            super(context);
+        }
+    }
+}