Add epoxy model layout view

epoxy-adapter/src/main/java/com/airbnb/epoxy/EpoxyModelWithLayoutView.java

@@ -0,0 +1,32 @@
+package com.airbnb.epoxy;
+
+import android.view.View;
+
+import androidx.annotation.LayoutRes;
+
+/**
+ * An {@link EpoxyModel} extension to abstract setup and usage of layout resource and span size.
+ *
+ * @see HiddenEpoxyModel
+ * @see SimpleEpoxyModel
+ */
+public class EpoxyModelWithLayoutView<T extends View> extends EpoxyModel<T> {
+
+  @LayoutRes protected final int layoutRes;
+  protected int spanCount;
+
+  public EpoxyModelWithLayoutView(@LayoutRes int layoutRes, int spanCount) {
+    this.layoutRes = layoutRes;
+    this.spanCount = spanCount;
+  }
+
+  @Override
+  protected int getDefaultLayout() {
+    return layoutRes;
+  }
+
+  @Override
+  public int getSpanSize(int totalSpanCount, int position, int itemCount) {
+    return spanCount;
+  }
+}

epoxy-adapter/src/main/java/com/airbnb/epoxy/HiddenEpoxyModel.java

@@ -10,14 +10,10 @@
  * Using a zero height and width {@link Space} view, as well as 0 span size, to exclude itself from
  * view.
  */
-class HiddenEpoxyModel extends EpoxyModel<Space> {
-  @Override
-  public int getDefaultLayout() {
-    return R.layout.view_holder_empty_view;
-  }
+class HiddenEpoxyModel extends EpoxyModelWithLayoutView<Space> {
 
-  @Override
-  public int getSpanSize(int spanCount, int position, int itemCount) {
-    return 0;
+  HiddenEpoxyModel() {
+    super(R.layout.view_holder_empty_view, 0 /*spanCount*/);
   }
+
 }

epoxy-adapter/src/main/java/com/airbnb/epoxy/SimpleEpoxyModel.java

@@ -12,13 +12,11 @@
  * subclass. This is useful for static layouts. You can also specify an onClick listener and the
  * span size.
  */
-public class SimpleEpoxyModel extends EpoxyModel<View> {
-  @LayoutRes private final int layoutRes;
+public class SimpleEpoxyModel extends EpoxyModelWithLayoutView<View> {
   private View.OnClickListener onClickListener;
-  private int spanCount = 1;
 
   public SimpleEpoxyModel(@LayoutRes int layoutRes) {
-    this.layoutRes = layoutRes;
+    super(layoutRes, 1 /*spanCount*/);
   }
 
   public SimpleEpoxyModel onClick(View.OnClickListener listener) {
@@ -46,16 +44,6 @@ public void unbind(@NonNull View view) {
     view.setOnClickListener(null);
   }
 
-  @Override
-  protected int getDefaultLayout() {
-    return layoutRes;
-  }
-
-  @Override
-  public int getSpanSize(int totalSpanCount, int position, int itemCount) {
-    return spanCount;
-  }
-
   @Override
   public boolean equals(Object o) {
     if (this == o) {

epoxy-adapter/src/test/java/com/airbnb/epoxy/EpoxyModelWithLayoutViewTest.kt

@@ -0,0 +1,20 @@
+package com.airbnb.epoxy
+
+import android.widget.Space
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@RunWith(JUnit4::class)
+class EpoxyModelWithLayoutViewTest {
+
+    @Test
+    fun `EpoxyModelWithLayoutView relays specified values from constructor`() {
+        val layoutRes = 12
+        val spanCount = 4
+        val model = EpoxyModelWithLayoutView<Space>(layoutRes, spanCount)
+
+        assert(model.defaultLayout == layoutRes)
+        assert(model.getSpanSize(100, 0, 10) == spanCount)
+    }
+}