add extra unit test - and fix up default version tagging - so both of the nodedefs with the new version can be selected

Author: ld-kerley

libraries/bxdf/usd_preview_surface.mtlx

@@ -52,7 +52,7 @@
 
   <!-- adding variant with scale and bias defined as vector4 type - we may decide to remove the original version
     in a future MaterialX version with an upgrade function -->
-  <nodedef name="ND_UsdUVTexture_23_vector4" node="UsdUVTexture" nodegroup="texture2d" version="2.3">
+  <nodedef name="ND_UsdUVTexture_23_vector4" node="UsdUVTexture" nodegroup="texture2d" version="2.3" isdefaultversion="true">
     <input name="file" type="filename" value="" uniform="true" />
     <input name="st" type="vector2" defaultgeomprop="UV0" />
     <input name="wrapS" type="string" value="periodic" enum="black,clamp,periodic,mirror" uniform="true" />

resources/Materials/Examples/UsdPreviewSurface/usd_preview_surface_brass.mtlx

@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<materialx version="1.39" colorspace="lin_rec709">
+  <UsdUVTexture name="image_color" type="multioutput">
+    <input name="file" type="filename" value="../../../Images/brass_color.jpg" colorspace="srgb_texture" />
+  </UsdUVTexture>
+  <UsdUVTexture name="image_roughness" type="multioutput">
+    <input name="file" type="filename" value="../../../Images/brass_roughness.jpg" />
+  </UsdUVTexture>
+  <UsdPreviewSurface name="SR_brass1" type="surfaceshader">
+    <input name="diffuseColor" type="color3" nodename="image_color" output="rgb" />
+    <input name="metallic" type="float" value="1" />
+    <input name="roughness" type="float" nodename="image_roughness" output="r" />
+  </UsdPreviewSurface>
+  <surfacematerial name="USD_Tiled_Brass" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="SR_brass1" />
+  </surfacematerial>
+</materialx>

resources/Materials/Examples/UsdPreviewSurface/usd_preview_surface_brass_vector_scale.mtlx

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<materialx version="1.39" colorspace="lin_rec709">
+  <UsdUVTexture name="image_color" type="multioutput">
+    <input name="file" type="filename" value="../../../Images/brass_color.jpg" colorspace="srgb_texture" />
+    <input name="scale" type="vector4" value="0.5, 0.5, 0.5, 1" />
+  </UsdUVTexture>
+  <UsdUVTexture name="image_roughness" type="multioutput">
+    <input name="file" type="filename" value="../../../Images/brass_roughness.jpg" />
+  </UsdUVTexture>
+  <UsdPreviewSurface name="SR_brass1" type="surfaceshader">
+    <input name="diffuseColor" type="color3" nodename="image_color" output="rgb" />
+    <input name="metallic" type="float" value="1" />
+    <input name="roughness" type="float" nodename="image_roughness" output="r" />
+  </UsdPreviewSurface>
+  <surfacematerial name="USD_Tiled_Brass" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="SR_brass1" />
+  </surfacematerial>
+</materialx>